STAR(1) Schily´s USER COMMANDS STAR(1)NAME
star - unique standard tape archiver
SYNOPSIS
star command [options] [-find] file1 ... filen [find_expr]
ustar command [options] [-find] file1 ... filen [find_expr]
tar command [options] file1 ... filen
star -copy [options] [-find] file1 ... [f_expr] directory
star -copy [options] -C from_directory . to_directory
DESCRIPTION
Star is a very fast tar(1) like tape archiver with improved functional‐
ity.
Star archives and extracts multiple files to and from a single file
called a tarfile. A tarfile is usually a magnetic tape, but it can be
any file. In all cases, appearance of a directory name refers to the
files and (recursively) subdirectories of that directory.
Star's actions are controlled by the mandatory command flags from the
list below. The way star acts may be modified by additional options.
Note that unpacking tar archives may be a security risk because star
may overwrite existing files. See SECURITY NOTES for more information.
FEATURES
Star includes the first free implementation of POSIX.1-2001 extended
tar headers. The POSIX.1-2001 extended tar headers define a new stan‐
dard way for going beyond the limitations of the historic tar format.
They allow (among others) to archive all UNIX time stamps in sub-second
resolution, files of arbitrary size and filenames without length limi‐
tation using UNICODE UTF-8 coding for best exchange compatibility.
Star by default uses a fifo to optimize data flow from/to tape. This
results in a normally streaming tape during the whole backup. See
-fifo and fs= option to get information on how to find the best fifo
size.
Star includes a pattern matcher to control the list of files to be pro‐
cessed. This gives a convenient interface for archiving and restoring
complex lists of files. In conjunction with the -w flag it is easy to
merge a tar archive into an existing file tree. See also -U option. In
create mode use the pat= option to specify either select or exclude
patterns (depending on the -V flag). In extract or list mode all file
type arguments are interpreted as select patterns while the patterns
specified with the pat= option may be used as select or exclude pat‐
terns (depending on the -V flag). Have a look at the description of
the -C option to learn how to fetch files from a list of directories
(in create mode) or to distribute files to a list of directories (in
extract mode). A substitute option allows ed(1) like pattern substitu‐
tion in file names.
Star includes an enhanced function that is similar to the find(1) com‐
mand (see sfind(1)). This allows to use find expressions, even in
extract or list mode, directly on the content on an archive. The
extensions to find(1) allow to modify the file metadata.
Star includes a sophisticated diff command. Several diff options allow
user tailorable functionality. Star won't show you differences you are
not interested in. Check the diffopts= option for more details.
Star has no limitation on filename length. Pathnames and linknames up
to PATH_MAX (1023 bytes with old OS versions and 4095 bytes with
POSIX.1-2001) may be archived. Later versions may be able to deal with
longer pathnames.
Star deals with all 3 times, available for files on UNIX systems if the
archive format is either chosen from the star specific formats or is a
format that uses POSIX.1-2001 extended headers. This is either done in
second resolution by using a star specific POSIX.1-1988 compatible
extension or in sub second resolution by using POSIX.1-2001 extended
headers. Star is able to store and restore all 3 times (mtime, atime
and even ctime). On Solaris 2.x systems, star is able to do backups
without changing any of the 3 the times.
If used with the H=ustar option, or if called as ustar or tar while the
H=headertype option is not used, star is 100% POSIX compliant.
Star's default format (if called as star) is xstar and is as posix com‐
pliant as possible. Enhancements to the standard that prevent correct
extraction of single files when using a different tar implementation
that is only POSIX.1-1988 compliant may occur, but they only affect
single files with a pathname that is longer than 100+130 chars or when
archiving sparse files with the -sparse option in effect. All other
files will extract correctly. See the description for the H=headertype
option below for more information on archive formats and possible ar‐
chive interchange problems.
Star makes it easy to repair corrupted filesystems. After a fsck -y has
been run on the filesystem, star is able to restore only the missing
files automatically. Use then star -diff to check for differences (see
EXAMPLES for more information).
Star automatically recognizes the type of the archive. Star therefore
is able to handle features and properties of different archive types in
their native mode, if it knows about the peculiarities of the archive
type. See the H=headertype option for more details. To be able to do
this, star adds hidden fingerprints to the archive header that allows
to recognise all star specific archive formats. The GNU tar format is
recognised by the way it deviates from the standard.
Star automatically recognizes and handles byte swapped archives. There
is no option to manually control byte swapping.
Star automatically recognizes and handles compressed archives inside
plain files.
Star is able to archive and restore Access Control Lists for files
using POSIX.1-2001 extended headers.
COMMAND
In native mode, star is compatible to the command line syntax of a typ‐
ical POSIX command and for this reason expects commands and options to
start with a single dash (-). In this case, commands and options may be
specified separately, all boolean or increment type options may be
specified either separately or combined. For compatibility with GNU
programs, long options may alternatively start with a double dash. In
compatibility mode to POSIX tar, star expects commands and options to
appear as one single string that does not start with a dash. In POSIX
tar compatibility mode, additional non POSIX options may be specified
but must appear after the POSIX options and their args and need to
start with a dash.
-c Create a new tarfile and write named files into it. Writing
starts at the beginning of tarfile. See -v option for informa‐
tion on how to increase verbosity while the archive is written.
-copy Copy named files to the target directory which is the last file
type argument. The target directory must exist. The shorthand
-cx instead of -copy is not allowed because this could be a
result of a typo.
If the option -diff has been specified in addition, star per‐
forms a one pass directory tree compare instead of copying
files. The shorthand -c -diff instead of -copy-diff is also
allowed.
On operating systems with slow file I/O (such as Linux), it may
help to use -no-fsync in addition, but then star is unable to
detect all error conditions; so use with care.
If the option -t has been specified in addition, the last file
type argument is not a target directory and star is performing a
one pass listing instead of copying files. This makes sense as
the listing from star may be better readable than the output
from ls -lR. The shorthand -c -t or -ct instead of -copy -t is
also allowed.
The job is by default done in the best archive mode. This
implies that it defaults to H=exustar -dump. When in -copy
mode, star forks into two processes and data exchange is done
via the shared memory from the FIFO. This gives the best possi‐
ble performance. Without FIFO, the -copy mode will not work.
The list= option, patterns and substitutions apply only to the
create side of the copy command.
-diff Compare the content and the attributes of the files from the ar‐
chive in tarfile to the filesystem. This may also be used to
compare two file trees in the filesystem. If you use a set of
diffopts that fits your needs, it will give - in many cases - a
more readable output than diff -r. If you use star's dump
extensions for the tar archive, the -diff option allows to find
even if the directory in the file tree contains more files than
the archive. This way, it is possible to compare all properties
of two file trees in one run. See diffopts for more details.
Adding one or more -v options increases the verbosity. With -vv
and above, the directory content is compared also if star is
reading a tar archive that has been created in -dump mode.
-n No extraction. Show what star would do, in case the -x command
had been specified.
-r Replace files in a tarfile. The named files are written to the
end of tarfile. This implies that later, the appropriate files
will be found more than once on the tarfile.
-t Table of contents. List the contents of the tarfile. If the -v
flag is used, the listing is similar to the format of ls -l out‐
put. With this option, the flags -a, -atime and -ctime have a
different meaning if the archive is in star, xstar, xustar,
exustar, or pax format. The option -a or -atime lists the
access time instead of the modification time, the option -ctime
lists the file creation time instead of the modification time.
The option -tpath may be used in addition to modify the output
so it may be used in shell scripts.
-u Update a tarfile. The named files are written to the end of
tarfile if they are not already there or if the files are newer
than the files of the same name found in the archive. The -r
and -u command only work if the tar archives is a regular file
or if the tar archive is an unblocked tape that may backspace.
-x Extract the named files from the tarfile. If no filename argu‐
ment or pattern is specified, the entire content of the tarfile
is restored. If the -U flag is not used, star extracts no file
which is older than the corresponding file on disk.
On operating systems with slow file I/O (such as Linux), it may
help to use -no-fsync in addition, but then star is unable to
detect all error conditions; so use with care.
Except for the shorthands documented above, exactly one of the commands
above must be specified.
If one or more patterns or substitution commands have been specified,
they apply to any of the command listed above. In copy mode, all pat‐
terns and substitute commands apply to the create side.
OPTIONS-help Print a summary of the most important options for star(1).
-xhelp Print a summary of the less important options for star(1).
-/ Don't strip leading slashes from file names when extracting an
archive. Tar archives containing absolute pathnames are usually
a bad idea. With other tar implementations, they may possibly
never be extracted without clobbering existing files. Star for
that reason, by default strips leading slashes from filenames
when in extract mode. As it may be impossible to create an ar‐
chive where leading slashes have been stripped while retaining
correct path names, star does not strip leading slashes in cre‐
ate mode.
See SECURITY NOTES for more information.
-.. Don't skip files that contain /../ in the name. Tar archives
containing names with /../ could be used to compromise the sys‐
tem. If they are unpacked together with a lot of other files,
this would in most cases not even be noticed. For this reason,
star by default does not extract files that contain /../ in the
name if star is not in interactive mode (see -w option).
See SECURITY NOTES for more information.
-7z run the input or output through a p7zip pipe - see option -z
below.
Note that the p7zip program currently does not operate on a pipe
but on a /tmp file copy and thus limits the maximum archive
size.
-0
-1
-2
-3
-4
-5
-6
-7 Select an archive entry from /etc/default/star. The format for
the archive entries is the same as the format in
/etc/default/tar in Solaris.
-acl Handle Access Control List (ACL) information in create and
extract mode. If -acl has been specified, star is in create
mode and the header type is exustar, star will add ACL informa‐
tion to the archive using POSIX.1-2001 extended headers. If
-acl has been specified and star is in extract mode, star will
try to restore ACL information. If there is no ACL information
for one or all files in the archive, star will clear the ACL
information for the specific file. Note that if -acl has not
been specified, star will not handle ACL information at all and
files may inherit ACL information from the parent directories.
If the -acl option has been specified, star assumes that the -p
option has been specified too.
artype=headertype
Generate a tape archive in headertype format. If this option is
used in extract/list mode this forces star to interpret the
headers to be of type headertype. As star even in case of a
user selected extract archive format does format checking, it
may be that you will not be able to unpack a specific archive
with all possible forced archive formats. Selecting the old tar
format for extraction will always work though. Valid parameter
for headertype are:
help Print a help message about possible header types.
v7tar Old UNIX V7 tar format. This archive format may only
store plain files. Pathnames or linknames longer than
99 chars may not be archived.
If the v7tar format has been selected, star will not
use enhancements to the historic UNIX V7 tar format.
File size is limited to 2 GB - 2 bytes, uid/gid is
limited to 262143. Sparse files will be filled up
with zeroes.
tar Old BSD UNIX tar format. This archive format may only
store plain files, directories and symbolic links.
Pathnames or linknames longer than 99 chars may not be
archived. See also the -d option as a note to some
even older tar implementations.
If the tar format has been selected, star will not use
enhancements to the historic tar format. File size is
limited to 2 GB - 2 bytes, uid/gid is limited to
262143. Sparse files will be filled up with zeroes.
star Old star standard format. This is an upward/downward
compatible enhancement of the old (pre Posix) UNIX tar
format. It has been introduced in 1985 and therefore
is not Posix compliant. The star format allows to ar‐
chive special files (even sockets) and records access
time and creation time besides the modification time.
Newer versions of the old star format allow very long
filenames (100+155 chars and above), linknames > 100
chars and sparse files (if -sparse is used). This
format is able to copy the device nodes on HP-UX that
have 24 bits in the minor device number, which is more
then the 21 bits that are possible with the
POSIX-1003.1-1988 archive format.
The nonstandard extensions are located in the space
between the link name and the POSIX file name prefix.
As the star format does not use a POSIX magic string,
the extensions do not interfere with the POSIX tar
formats. The last 4 bytes of the tar header contain a
'tar\0' signature.
gnutar This is a commonly used, but unfortunately not Posix
compliant (although designed after 1987) enhancement
to the old tar format. The gnutar format has been
defined between 1989 and 1994. Do not use the gnutar
archive format unless you want to create an archive
for a target system that is known to have only the
gnutar program available. The gnutar archive format
violates basic rules for any (even the historic) tar
archive format, in special when sparse files are
archived using the -sparse option. Using the gnutar
archive format causes a high risk that the resulting
archive may only be read by gnutar or by star. The
implementation of the gnutar archive format within
star is not complete, but sufficient for most gnutar
archives. See NOTES for more information.
ustar IEEE/Posix1003/IEC-9945-1-1988 Standard Data Inter‐
change format. With this option in effect, star will
generate 100% POSIX.1-1988 compliant tar archives.
Files with pathnames longer than 100+155 chars or
linknames longer than 100 chars may not be archived.
If star is called as ustar the default archive format
is ustar.
If the ustar format has been selected, star will not
use enhancements to the POSIX.1-1988 tar format, the
archive will be strictly conforming. File size is
limited to 8 GB, uid/gid/major/minor is limited to
2097151. Sparse files will be filled up with zeroes.
pax The IEEE/Posix1003/IEC-9945-1-1988 successor is the
POSIX-1003.1-2001 Standard Data Interchange format.
It is called the pax archive format.
If the pax format has been selected, star will not use
enhancements to the POSIX.1-2001 tar format, the ar‐
chive will be strictly conforming. File size is
unlimited, uid/gid/uname/gidname is unlimited,
major/minor is limited to 2097151. Sparse files will
be filled up with zeroes.
xstar The extended standard tar format has been introduced
in 1994. Star uses the xstar format as default ar‐
chive format. This is an upward/downward compatible
enhancement of the IEEE/Posix1003/IEC-9945-1 Standard
Data Interchange format. It allows among others very
long filenames (100+130 chars and above) and records
access time and creation time. Sparse files will be
archived correctly (if -sparse is used).
The access time and creation time are stored at the
end of the POSIX file name prefix (this limits the
prefix to 130 chars). These extensions do not inter‐
fere with the POSIX standard as the fields for mtime
and ctime field are always separated from the POSIX
file name prefix by a null byte. The last 4 bytes of
the tar header contain a 'tar\0' signature.
The xstar format is the default format when star is
neither called as tar nor called as ustar.
xustar A new format introduced 1998, that omits the 'tar\0'
signature at the end of the tar header. It is other‐
wise identical to the xstar format. As some tar
implementations do not follow the POSIX rules and com‐
pute the checksum for less than 512 bytes of the tar
header, this format may help to avoid problems with
these broken tar implementations. The main other dif‐
ference to the xstar format is that the xustar format
uses POSIX.1-2001 extended headers to overcome limita‐
tions of the historic tar format while the xstar for‐
mat uses proprietary extensions. The xustar format is
the default format when star is called as tar.
File size is unlimited, uid/gid/uname/gidname is
unlimited, major/minor is unlimited. Sparse files
will be archived correctly (if -sparse is used).
exustar A format similar to the xustar format but with forced
POSIX.1-2001 extended headers. If this format is used
together with the -acl option, star records Access
Control Lists (ACLs) in POSIX.1-2001 extended headers.
The exustar format allows to archive all file types
but it does not archive more than the POSIX.1-1988 set
by default. If the -dump option is used or if star is
otherwise on dump mode, star archives all file types
and in addition archives more meta data then usual.
File size is unlimited, uid/gid/uname/gidname is
unlimited, major/minor is unlimited. Sparse files
will be archived correctly (if -sparse is used).
suntar The extended header format found on Solaris 7/8/9.
This format is similar to the pax format but does not
handle atime and ctime and in addition uses 'X' as the
typeflag for the extended headers instead of the stan‐
dard 'x'.
File size is unlimited, uid/gid/uname/gidname is
unlimited, major/minor is unlimited. Sparse files
will be filled up with zeroes.
bin The cpio UNIX V7 binary format. This is a format with
big interoperability problems. Try to avoid this for‐
mat. It is only present to make the scpio command
SVr4 compliant.
cpio The POSIX.1-1988 cpio format. This format uses octal
ascii headers. A similar format is created by calling
cpio -o-c on pre SYSVr4 systems and by calling cpio
-o -Hodc on SYSVr4 systems. The POSIX.1-1988 cpio
format allows a file name length up to 262142 charac‐
ters and allows to archive nearly any file type. File
size is limited to 8 GB, uid/gid/st_dev is limited to
262143. The way major and minor device numbers are
stored inside the st_dev field is implementation
dependent.
Even though this archive format is covered by the
POSIX.1-1988 standard, it has a lower portability than
the ustar format. Try to avoid the cpio archive for‐
mat.
odc This archive format is similar to the The POSIX.1-1988
cpio format but the file name length is limited to 255
characters and the socket file type is not allowed.
This archive format has been introduced to allow non
POSIX cpio implementations such as the cpio program on
SYSV to accept the archive. Use this format whenever
you are not sure if the target system offers a fully
POSIX compliant cpio program.
Even though this archive format is covered by the
POSIX.1-1988 standard, it has a lower portability than
the ustar format. Try to avoid the odc archive format.
asc Tell star to create a cpio archive in the ascii format
that is created with cpio -o -c on SYSVr4 systems. It
uses extended (32 bit) numbers for uid's, gid's and
device numbers but limits the file size to 4 GB - 2
bytes although the format has been specified after the
POSIX.1-1988 cpio format. Try to avoid the asc ar‐
chive format because of its limited portability.
crc This format is similar to the asc cpio format but in
addition uses a simple byte based checksum called here
as CRC. This algorithm is simple Sum32 -- not a poly‐
nomial CRC. Try to avoid the crc archive format
because of its limited portability.
All tar archive formats may be interchanged if the archive con‐
tains no files that may not be archived by using the old tar
format. Archives in the xstar format may be extracted by any
100% POSIX compliant tar implementation if they contain no files
with pathnames > 100+130 chars and if they contain no sparse
files that have been archived by using the -sparse option.
-ask_remove
obsoleted by -ask-remove
-ask-remove
Ask to remove non writable files on extraction. By default,
star will not overwrite files that are read only. If this
option is in effect, star will ask whether it should remove
these files to allow the extraction of a file in the following
way:
remove 'filename' ? Y(es)/N(o) :
-atime, -a
Reset access time of files after storing them to tarfile. On
Solaris 2.x, (if invoked by root) star uses the _FIOSATIME ioctl
to do this. This enables star not to trash the ctime while
resetting the atime of the files. If the -atime option is used
in conjunction with the list command, star lists access time
instead of modification time. (This works only in conjunction
with the star, xstar, xustar, exustar, and with the pax format.)
Another option to retain the access time for the the files that
are going to be archives is to readonly mount a UFS snapshot and
to archive files from the mount point of the UFS snapshot.
-B Force star to perform multiple reads (if necessary) to fill a
block. This option exists so that star can work across the Eth‐
ernet, since pipes and sockets return partial blocks even when
more data is coming. If star uses stdin as archive file, star
behaves as if it has been called with the -B option. For this
reason, the option -B in practice is rarely needed.
-block-number
Print the archive block number (archive offset / 512) at the
beginning of each line when in verbose mode. This allows to
write backup scripts that archive the offsets for files and that
use
mt fsr blockno
to skip to the tape block number of interest in a fast way if a
single file needs to be restored.
blocks=#, b=#
Set the blocking factor of the tarfile to # times 512 bytes
(unless a different multiplication factor has been specified -
see bs= option for possible multiplication factors). Changing
the blocking factor only makes sense when the archive is located
on a real tape device or when the archive is accessed via the
remote tape protocol (see f= option below). The default is to
use a blocking factor of 20 i.e. 10 kBytes. Increasing the
blocksize will speed up the backup. For portability with very
old tar implementations (pre BSD 4.2 or pre AT&T SVR4), block‐
size should not be more than 10 kBytes. For POSIX.1-1988 com‐
patibility, blocksize should be no more than 10 kBytes. For
POSIX.1-2001 compatibility, blocksize should be no more than
32 kBytes. Most systems also have a hardware limitation for the
blocksize, 32 kBytes and 63 kBytes are common limits on many
systems. The upper limit in any case is the size of the buffer
RAM in the tape drive. Make a test if you want to make sure
that the target system will handle the intended blocksize. If
you use star for data exchange via tape, it is a good idea to
use a blocksize of 10 kBytes unless you are sure that the read‐
ing system will handle a larger blocksize. If you use star for
backup purposes with recent hardware (e.g. DLT tape drives), a
blocksize of 256 kBytes results in sufficient speed and seems to
be a good choice. Star allows block sizes up to 2 GByte if the
system does not impose a smaller limit. If you want to deter‐
mine the blocking factor when reading an unknown tar archive on
tape, specify a blocking factor that is higher than the supposed
blocking factor of the tape. Star then will determine the
blocking factor by reading the first record of the tape and
print a message:
star: Blocksize = # records.
Where # is the blocking factor in multiples of 512 bytes. The
blocks= option and the bs= option are equivalent methods to
specify the tape block size. The blocks= option is preferred by
people who like to use an option that behaves similar to the
interface of the historic tar(1) implementations.
bs=# Set output block size to #. You may use the same method as in
dd(1) and sdd(1). The number representing the size is taken in
bytes unless otherwise specified. If a number is followed
directly by the letter `.', `w', `b', `k', `m', `g', `t', or
`p', the size is multiplied by 1, 2, 512, 1024, 1024*1024,
1024*1024*1024, 1024*1024*1024*1024 or 1024*1024*1024*1024*1024.
If the size consists of numbers separated by `x' or `*', multi‐
plication of the two numbers is performed. Thus bs=7x8k will
specify a blocksize of 56 kBytes. Blocksize must be a multiple
of 512 bytes. See also the description of the blocks= option
for more details on blocksizes. The option bs= is preferred by
people who like to use an option that behaves similar to the
interface used by dd(1) and sdd(1).
-bsdchdir
Switch the behavior of the C= option to BSD style. The default
behavior of star is to stay in a working directory until a new
C= is seen. With BSD tar, the C= option is only related to the
next file type argument.
-bz run the input or output through a bzip2 pipe - see option -z-Z
and -j below. As the -bz the -j the -Z and the -z option are
non standard, it makes sense to omit the -bz the -j the -Z and
the -z options inside shell scripts if you are going to extract
a compressed archive that is located inside a plain file as star
will auto detect compression and choose the right decompression
option to extract.
C=dir
-C dir Perform a chdir(2) operation to dir before storing or extracting
the next files. In all cases, star will perform the chdir(2)
operation relative to the current working directory of the
shell.
· In list mode (with the -t flag), star ignores all -C
options.
· In create mode (with the -c, -r and -u flag), star walks
through all -C options and file type arguments. While a
BSD derived tar(1) implementation goes back to the cur‐
rent working directory after storing one file argument
that immediately follows the -C option, star changes the
directory only if a new -C option follows. To emulate
the behavior of a BSD derived tar(1), add a -C . option
after the file argument.
· In extract mode (with the -x, -n and -diff flag), star
builds a pattern list together with corresponding direc‐
tories from previous C=dir options and performs a
chdir(2) to the corresponding directory of a matching
pattern. All pat= options that do not follow a C=dir
option are interpreted as if they were preceded by a -C .
option. See EXAMPLES for more information.
compress-program=name
Set a named compress program. The program must compress in a
pipe when called without parameters and decompress when run with
the -d option in a pipe. This option is otherwise similar to
the -z the -j the -Z and the -bz option.
-copydlinks
Try to recursively copy the content of linked directories
instead of creating the link. This is an experimental feature
that may help to unpack archives on DOS.
-copyhardlinks
This option allows to copy hardlinked targets rather than creat‐
ing the link. It helps to extract tar files on systems that do
not implement hardlinks (e.g. BeOS).
-copylinks
This option allows to copy both, hard- and symlinked targets
rather than creating a link. It helps to extract tar files on
systems that do not implement links (e.g. OS/2). To extract and
copy all symlinks correctly, you may need to call star twice as
star cannot copy files that appear in the archive later than a
symlink pointing to them.
-copysymlinks
This option allows to copy symlinked targets rather than creat‐
ing a symbolic link. It helps to extract tar files on systems
that do not implement links (e.g. OS/2). To extract and copy
all symlinks correctly, you may need to call star twice as star
cannot copy files that appear in the archive later than a sym‐
link pointing to them.
-cpio-statistics
Instead of the star flavor of the statistics, print statistics
in cpio flavor.
-ctime If used with the list command, this lists ctime rather than
mtime if the archive format is star, xstar, xustar, exustar, or
pax.
If star is run as root and if -ctime is used with the extract
command and the same archive formats, this causes star to try to
restore even the ctime of a file by generating time storms. You
should not do this when in multi user mode because this may con‐
fuse programs like cron and the news system. Although star
tries to eliminate the accumulative effects of the time storm,
there is a tendency for the system clock to slow down a bit.
The clock typically lags about one millisecond per extracted
file. Use with care and check the system clock after using this
feature.
If used with the create command this changes the behavior of the
newer= option. Star, in this case compares the ctime of all
files to the mtime of the stamp file rather then comparing the
mtimes of both files.
-cumulative
A shorthand for -dump-cumulative. See -dump-cumulative for more
information.
-D Do not descend directories when in create mode. Normally, star
descends the whole tree if it encounters a directory in in its
file parameters. The option -D is in effect by default if the
list=file option is used. If you like star to descend directo‐
ries found in the list file, use the -dodesc option (see below).
-d Do not store/create directories. Old versions of tar such as
published with the seventh edition of UNIX are not able to deal
with directories in tar archives. If a tar archive is generated
without directories this avoids problems with tar implementa‐
tions found on SYSVr3 and earlier. If used during extract, no
intermediate missing directories are created.
-data-change-warn
If the size of a file changes while the file is being archived,
treat this condition as a warning only that does not cause a non
zero exit code. A warning message is still written if the con‐
dition is not otherwise ignored by another rule from an errctl=
option. The -data-change-warn option works as if the last error
control option was
errctl="WARN|GROW|SHRINK *"
The -e option or an ABORT entry in a condition set up by errctl=
has a higher precedence than the -data-change-warn option. This
option is ignored in extract or list mode.
-debug Print debug messages. Among other things, this gives debug mes‐
sages for header type recognition, tar type properties, EOF
recognition, opening of remote archives and fifo internals.
diffopts=optlst
Comma separated list of diffopts. Valid members in optlst are:
help Print a summary of possible members of the diffopts
list.
! Invert the meaning of the following string. No comma
is needed after the exclamation mark.
not Invert the meaning of all members in the diffopts list
i.e. exclude all present options from an initially
complete set compare list. When using csh(1) you
might have problems to use ! due to its strange
parser. This is why the not alias exists.
perm Compare file permissions. With this option in effect,
star compares the low order 12 bits of the st_mode
field.
mode Same as perm.
symperm Compare permissions even in case the target file on
the local filesystem is a symbolic link. By default,
star will not compare the permission of symbolic links
as most systems cannot set the permission of symbolic
links. Star compares symperm only if perm is compared
also.
type Compare file type. Note that star cannot compare the
file type in case of a hard link.
nlink Compare link count on hardlinks. This only works if
the archive is in exustar format and contains star's
dump extensions.
uid Compare numerical user id of file.
gid Compare numerical group id of file.
uname Compare ASCII version of user id of file. The user
name is mapped via the file /etc/passwd.
gname Compare ASCII version of group id of file. The group
name is mapped via the file /etc/group.
id Shorthand for: uid,gid,uname,gname. Compare all
user/group related info of file. Note that this will
always find differences if the source and target sys‐
tem use different user or group mappings.
size Compare file size. Note that star cannot compare the
file size in case of a hard link.
data Compare content of file. If star already found that
the size of the files differ, it will not compare the
content anymore. If the size of the files differ,
star will always report different data.
cont Same as data.
rdev Compare major/minor numbers for device nodes.
hardlink Compare target of hardlinks.
symlink Compare target of symlinks. This evaluates the paths
returned by the readlink(2) call.
Two symlinks are considered equal, it they either have
a characterwise identical link-name, or if they either
both use an absolute path name or both use a relative
path name and the following is true: Both symlinks
point to the same file that must exist or both path‐
names look similar enough.
sympath Compare the target pathnames of symlinks. This charac‐
terwise compares the strings returned from the read‐
link(2) call.
sparse Compare if either both files are sparse or not. If
only one of both files is sparse, then a difference is
flagged. This only works with if the archive format
is star, xstar, xustar, exustar, or gnutar.
atime Compare access time of file. This only works with if
the archive format is star, xstar, xustar, exustar, or
pax.
mtime Compare modification time of file.
ctime This only works with if the archive format is star,
xstar, xustar, exustar, or pax.
lmtime Compare the modification time even in case the target
file on the local filesystem is a symbolic link. By
default, star will not compare the modification time
of symbolic links as most systems cannot set the modi‐
fication time of symbolic links. Star compares lmtime
only if mtime is compared also.
times Shorthand for: atime,mtime,ctime.
dir Compare the content of directories. This only works
if the archive is in exustar format and contains
star's dump extensions. Together with increased ver‐
bose level (-vv) this will print a list of files that
are only in the archive and a list of files that are
only on the current filesystem.
xtimes Shorthand for: atime,mtime,ctime,lmtime.
acl Compare access control lists. This only works if the
archive is in exustar format and has been created with
star's -acl option. You need to specify the -acl
option in addition when running the diff.
xattr Compare extended file attributes. This only works if
the archive is in exustar format and has been created
with star's -xattr option. You need to specify the
-xattr option in addition when running the diff.
fflags Compare extended file flags. This only works if the
archive is in exustar format and has been created with
star's -xfflags option. You need to specify the
-xfflags option in addition when running the diff.
If optlst starts with a ! the meaning of all members in optlst
is inverted as with the not optlist member. In this case, star
starts with a complete list that includes atime and lmtime.
Reasonable diff options to use when comparing against a copy of
a directory tree are diffopts=!atime,ctime,lmtime.
If diffopts are not specified, star compares everything but the
access time of the files and the modification time of symbolic
links.
dir-group=group
If star extracts archives as root, this option allows to control
the group id of intermediate directories created by star.
dir-owner=user
If star extracts archives as root, this option allows to control
the owner of intermediate directories created by
-dirmode
If in create mode (i.e. when storing files to archive), star
stores directories past the corresponding files. This guarantees
that even old tar implementations without a directory cache will
be able to restore the correct times of directories. The option
-dirmode should only be used if the archive needs to be
extracted by an old tar implementation. If star is used to
extract an archive that has been created with -dirmode the
directories will not get an old time stamp unless the option -U
is used while extracting the archive.
-dodesc
Force star to descend directories found in a list=file. See
also the -D option above. The -dodesc option only works in cre‐
ate mode.
-dump Allows to create archives with the same number of attributes as
an archive that has been created with the level= option but
without the restrictions that apply to a true dump.
The resultant archive may be seen as a level-less dump which
includes similar attributes as a level 0 dump but may span more
than a single file system and does not need to use a -C option.
It has been originally introduced to make it easier to implement
a star version that supports true incremental dumps, but it is
kept as it gives additional benefits. Star currently sets the
archive type to exustar and, in addition archives more inode
meta data inside POSIX.1-2001 extended headers. See also level=
option and the section INCREMENTAL BACKUPS for more information
on true incremental dumps.
-dump-cumulative
instructs star to perform incremental dumps relatively to the
last incremental dump of the same level. Incremental dumps with
a level higher than 0 are normally done relatively to the con‐
tent of a previous dump with lower level. If incremental dumps
and restores are going to be used to synchronize filesystem con‐
tent, every successive incremental dump will increase in size if
-dump-cumulative is not used. See section SYNCHRONIZING
FILESYSTEMS for more information.
dumpdate=name
Tells star to use the mtime of the time stamp file name instead
of using the start time of star. This is needed when star is
run on file system snapshots. If star would use the the start
time with snapshots, all files that have been modified between
the setup of the snapshot and the start of star would be missing
on the backup.
-dumpmeta
changes the behavior of star in incremental dump mode. If
-dumpmeta is used and only the inode change time (st_ctime) of a
file has been updated since the last incremental dump, star will
archive only the meta data of the file (e.g. uid, permissions,
...) but not the file content. Using -dumpmeta will result in
smaller incremental dumps, but files that have been created
between two incrementals and set to an old date in st_mtime
(e.g. as a result from a tar extract) will not be archived with
full content. Using -dumpmeta thus may result in incomplete
incremental dumps, use with extreme care.
-e Exit immediately with exit status -3 (253) if any unexpected
error occurs. The -e option works as if the last error control
option was
errctl="ABORT|ALL|DIFF *"
This allows to use the errctl= option together with the -e
option and thus to ignore some error conditions while aborting
on all other conditions.
errctl= name
errctl= error control spec
Add the content from file name to the error control definitions
or add error control spec to the error control definitions.
More than one error control file and more than one error control
spec as well as a mixture of both forms is possible.
The reason for using error control is to make star quiet about
error conditions that are known to be irrelevant on the quality
of the archive or restore run or to tell star to abort on cer‐
tain error conditions instead of trying to continue with the ar‐
chive.
A typical reason to use error control is to suppress warnings
about growing log files while doing a backup on a live file sys‐
tem. Another typical reason to use error control is to tell
star to abort if e.g. a file could not be archived instead of
continuing to archive other files from a list.
The error control file contains a set of lines, each starting
with a list of error conditions to be ignored followed by white
space followed by a file name pattern (see match(1) or pat‐
match(3) for more information). The error control spec uses the
same syntax as a single line from the error control file. If
the file name pattern needs to start with white space, use a
backslash to escape the start of the file name. It is not possi‐
ble to have new line characters in the file name pattern. When‐
ever an error situation is encountered, star checks the lines in
the error control file starting from the top. If the current
error condition is listed on a line in the error control file,
then star checks whether the pattern on the rest of the line
matches the current file name. If this is the case, star uses
the current error control specification to control the current
error condition.
The list of error conditions to be handled may use one or more
(in this case separated by a '|' character) identifiers from the
list below:
ABORT If this meta condition is included in an error con‐
dition, star aborts (exits) as soon as possible
after this error condition has been seen instead of
making star quiet about the condition. This error
condition flag may only be used together with at
another error condition or a list of error condi‐
tions (separated by a '|' character).
WARN If this meta condition is included in an error con‐
dition, star prints the warning about the error con‐
dition but the error condition does not affect the
exit code of star and the error statistics (which is
printed to the end) does not include the related
errors. This error condition flag may only be used
together with at another error condition or a list
of error conditions (separated by a '|' character).
The WARN meta condition has a lower precedence than
ABORT.
DIFF Suppress output in case that star -diff did
encounter any differences.
ALL This is a shortcut for all error conditions below.
STAT Suppress warnings that star could not stat(2) a
file.
GETACL Suppress warnings about files on which star had
problems to retrieve the ACL information.
OPEN Suppress warnings about files that could not be
opened.
READ Suppress warnings read errors on files.
WRITE Suppress warnings write errors on files.
READLINK Suppress warnings readlink(2) errors on symbolic
links.
GROW Suppress warnings about files that did grow while
they have been archived.
SHRINK Suppress warnings about files that did shrink while
they have been archived.
MISSLINK Suppress warnings about files for which star was
unable to archive all hard links.
NAMETOOLONG Suppress warnings about files that could not be
archived because the name of the file is too long
for the archive format.
FILETOOBIG Suppress warnings about files that could not be
archived because the size of the file is too big for
the archive format.
SPECIALFILE Suppress warnings about files that could not be
archived because the file type is not supported by
the archive format.
GETXATTR Suppress warnings about files on that star could not
retrieve the extended file attribute information.
SETTIME Suppress warnings about files on that star could not
set the time information during extraction.
SETMODE Suppress warnings about files on that star could not
set the access modes during extraction.
SECURITY Suppress warnings about files that have been skipped
on extraction because they have been considered to
be a security risk. This currently applies to all
files that have a '/../' sequence inside when -..
has not been specified.
LSECURITY Suppress warnings about links that have been skipped
on extraction because they have been considered to
be a security risk. This currently applies to all
link names that start with '/' or have a '/../'
sequence inside when -secure-links has been speci‐
fied. In this case, star tries to match the link
name against the pattern in the error control file.
SAMEFILE Suppress warnings about links that have been skipped
on extraction because source and target of the link
are pointing to the same file. If star would not
skip these files, it would end up with removing the
file completely. In this case, star tries to match
the link name against the pattern in the error con‐
trol file.
BADACL Suppress warnings access control list conversion
problems.
SETACL Suppress warnings about files on that star could not
set the ACL information during extraction.
SETXATTR Suppress warnings about files on that star could not
set the extended file attribute information during
extraction.
If a specific error condition is ignored, then the error condition is
not only handled in a silent way but also excluded from the error sta‐
tistics that are printed at the end of the star run.
Be very careful when using error control as you may ignore any error
condition. If you ignore the wrong error conditions, you may not be
able to see real problems anymore.
-exclude-from name
Exclude from named file, this is an alias for the -X option. See
-X option for more information.
-F,-FF ...
Fast and simple exclude option for create mode. With one -F
argument, star ignores all directories called SCCS and RCS.
With two -F arguments, star in addition ignores all files called
core errs a.out all files ending with .o. OBJ/. With three -F
arguments, star ignores all sub trees starting from a directory
that includes a file .mirror or .exclude and all object files
and files called core errs a.out all files ending with .o. With
four -F arguments, star ignores all sub trees starting from a
directory that includes a file .mirror or .exclude the latter
files are excluded too as well as and all object files and files
called core errs a.out all files ending with .o. With five -F
arguments, star in addition again excludes all directories
called SCCS and RCS.
-fifo Use a fifo to optimize data flow from/to tarfile. This option
is in effect by default (it may be changed at compile time).
The default fifo size is 8 MBytes on all platforms except Linux
versions that do not support mmap() (4 MB because kernels before
2.4 did not handle big shared memory areas) and Sun/mc68000 (1
MB). This will star make even work on a tiny machine like a Sun
3/50. The fifo size may be modified with the fs= option. A rule
of dumb for the fifo size is to use more than the buffer size of
the tape drive and less then half of the real memory of the
machine. A good choice would be to use a fifo size between 8
and 256 MB. This may increase backup speed up to 5% compared to
the speed achieved with the default fifo size. Note that with a
DLT drive that gives 12MB/s transfer rate, a fifo of 256 MB size
will keep the tape at least streaming in units of 20 seconds.
All options that start with the -f sequence are sensitive to
typo problems, see BUGS section for more information.
-fifostats
Print fifo statistics at the end of a star run when the fifo has
been in effect. All options that start with the -f sequence are
sensitive to typo problems, see BUGS section for more informa‐
tion.
file=tarfilename, f=tarfilename
Use tarfilename as the name for the tar archive. Currently up to
100 file= options are possible. Specifying more then one file=
option make sense in multi volume mode. In this case star will
use the next name in the list every time a media change is
needed. To make star behave consistent with the single file
case, star loops over the list of known archive files. Note
that if star is installed suid root and the first tarfile is a
remote archive, only the connection to this archive will be cre‐
ated with root privileges. After this connection has been
established as root, star switches back to the id of the caller.
If any of the other archives in the list is located on a differ‐
ent host, star will not be able to open this archive later on,
unless run by root.
Star normally uses stdin/stdout for the tar archive because the
most common way to use star is in conjunction with pipes. If
star is installed suid root or if it has been called by root,
tarfilename may be in remote syntax: user@host:filename as in
rcp(1) even if invoked by non root users. See SUID NOTES for
more information.
To make a file local although it includes a colon (:), the file‐
name must start with: '/', './' or '../'
Note that if star talks to an old rmt remote tape server that
does not support symbolic open modes, it does not open a remote
tape with the O_CREAT open flag because this would be extremely
dangerous. If the rmt server on the other side is the rmt
server that comes with star or the GNU rmt server, star may use
the symbolic mode for the open flags. Only the symbolic open
modes allow to send all possible open modes in a portable way to
remote tape servers.
It is recommended to use the rmt server that comes with star.
It is the only rmt server that gives platform independent com‐
patibility with BSD, Sun and GNU rmt clients and it includes
security features that may be set up in /etc/default/rmt. All
options that start with the -f sequence are sensitive to typo
problems, see BUGS section for more information.
See ENVIRONMENT section for information on how to use ssh(1) to
create a remote tape server connection.
Note that if file=- has been specified, it is no longer possible
to use the -find -exec primary.
-find This option acts a separator. If it is used, all star options
must be to the left of the -find option. To the right of the
-find option, star accepts the find command line syntax only.
The find expression acts as a filter between the source of file
names and the consumer, which may either be the archiving engine
or list/extract engine. If the find expression evaluated as
TRUE, then the related file is selected for processing, other‐
wise it is omited.
In order to make the evaluation of the find expression more con‐
venient, star implements additional find primaries that have
side effects on the file meta data. Star implements the follow‐
ing additional find primaries:
-chgrp gname
The primary always evaluates as true; it sets the group
of the file to gname.
-chmod mode
The primary always evaluates as true; it sets the permis‐
sions of the file to mode. Octal and symbolic permis‐
sions are accepted for mode as with chmod(1).
-chown uname
The primary always evaluates as true; it sets the owner
of the file to uname.
-false The primary always evaluates as false; it allows to make
the result of the full expression different from the
result of a part of the expression.
-true The primary always evaluates as true; it allows to make
the result of the full expression different from the
result of a part of the expression.
The command line:
star -c f=o.tar -find . ( -type d -ls -o false ) -o ! -type d
lists all directories and archives all non-directories to the
archive o.tar.
The command line:
star -c f=o.tar -find . ( -type d -chown root -o true )
archives all directories so they appear to be owned by root in
the archive, all non-directories are archived as they are in the
file system.
Note that the -ls, -exec and the -ok primary cannot be used if
stdin or stdout has been redirected by the list=- of by the
file=- options.
-force_hole
obsoleted by -force-hole
-force-hole
Try to extract all files with holes. This even works with files
that are created without the -sparse option. Star, in this case
examines the content of the files in the archive and replaces
writes to parts containing binary zeroes with seeks.
If used together with the -sparse option in create mode, star
assumes all files to be sparse and archives files with blocks of
nulls as sparse files.
This option should be used with extreme care because you some‐
times get in trouble when files get unattended holes. All
options that start with the -f sequence are sensitive to typo
problems, see BUGS section for more information.
-force_remove
obsoleted by -force-remove
-force-remove
Force to remove non writable files on extraction. By default,
star will not overwrite files that are read only. If this
option is in effect, star will silently remove these files to
allow the extraction of a file. All options that start with the
-f sequence are sensitive to typo problems, see BUGS section for
more information.
-force-restore
Force an incremental restore even if the incremental dump is
only a partial dump. See -wtardumps, level= and section INCRE‐
MENTAL BACKUPS for more information.
fs=# Set fifo size to #. See bs= for the possible syntax. The
default size of the fifo is 1 Mbyte on Sun mc68000 systems, 4
Mbytes on non mmap() aware Linux systems and 8 Mbytes on all
other systems. See -fifo option for hints on using the right
fifo size.
fs-name=mount_point
Use mount_point when recording information in /etc/tardumps and
when comparing against information in /etc/tardumps for incre‐
mental backups. This makes sense when backups are made using
file system snapshots and allows /etc/tardumps and the archive
to contain the real name of the file system instead of the tem‐
porary mount point that is used for the snapshot device.
H=headertype
See artype=headertype option. Note that POSIX.1-2001 defines an
option -H that follows symbolic links that have been encountered
on the command line. For this reason, the old star option
H=headertype option may go away in the future even though this
option has been in use by cpio since 1989.
-h, -L Follow symbolic links as if they were files. Normally star will
not follow symbolic links but stores their values in tarfile.
See also the -L option.
-hardlinks
In extract mode, this option tells star to try to create a
hardlink whenever a symlink is encountered in the archive. In
create mode, this option tells star to try to archive a hardlink
whenever a symlink is encountered in the file system.
-hpdev Allow 24 bits for the minor device number using 8 octal digits.
Note that although it allows to create tar archives that can be
read with HP-UX tar, this creates tar archives which violate
POSIX.1-1988. This option is only needed if you like to use a
POSIX.1-1988 based archive format that does not include exten‐
sions. If you use the xstar format, star will use a base 256
extension that allows bigger major/minor numbers by default, if
you use the xustar or the exustar format there is no limitation
at all as these formats use POSIX.1-2001 extended headers to ar‐
chive the major/minor numbers by default.
-i Ignore checksum errors on tar headers. If this option is speci‐
fied, star will not exit if a header with a bad checksum is
found but search for the next valid header.
-install
Carefully replace existing files when extracting files. This is
done similar to install(1) by first extracting the files into a
temporary name and renaming the file to the final name after the
extraction of that file was successful.
As star by default does not remove non-empty directories, an
install that needs to remove existing non-empty directories may
also need the options -force-remove and -remove-recursive.
-j run the input or output through a bzip2 pipe - see option -z -Z
and -bz below. As the -bz the -j the -Z and the -z option are
non standard, it makes sense to omit the -bz the -j the -Z and
the -z options inside shell scripts if you are going to extract
a compressed archive that is located inside a plain file as star
will auto detect compression and choose the right decompression
option to extract.
-keep-nonempty-dirs
Do not complain about trying to remove nonempty directories in
case that -remove-recursive has not been specified.
-keep_old_files
obsoleted by -keep-old-files
-keep-old-files, -k
Keep existing files rather than restoring them from tarfile.
This saves files from being clobbered even if tarfile contains a
more recent version of the corresponding file.
See SECURITY NOTES for more information.
-L, -h Follow symbolic links as if they were files. Normally star will
not follow symbolic links but stores their values in tarfile.
See also the -h option.
-l Do not print a warning message if not all links to hard linked
files could be dumped. This option is evaluated in the opposite
way to historic tar(1) implementations and to POSIX.1. POSIX.1
requests that by default no warning messages will be printed and
-l will enable warning messages when not all links could be
archived.
level=dumplevel
Set level for incremental dumps. This option is used to switch
star into true incremental dump mode. The dumplevel may be in
the range between 0..99.
In true incremental dump mode, a -C option which is followed by
the name a mount point and a dot ('.') as starting directory
name is required. Only a single file system may be handled at a
time. If the directory following the -C option is not referring
to a root directory of a file system, the dump is called a par‐
tial dump. If the directory following the -C option is refer‐
ring to a root directory of a file system and no other restric‐
tions apply that exclude certain files from the dump, the dump
is called a full dump.
By default, the tardumps database is not written. See also the
tardumps=name and -wtardumps options and the section INCREMENTAL
BACKUPS for more information.
-link-data
In create mode, include the data for files even if these files
are hard links. This feature in create mode is currently only
available for the exustar archive format and only in case
-sparse has not been specified.
In extract mode, allow star to deal with data in hard linked
files even if the standard would not allow this for the used ar‐
chive format.
-link-dirs
When in create mode, try to find hard linked directories. Using
-link-dirs will force star to keep track of all directories that
will go into the archive and thus causes a lot more memory to be
allocated than in the default case.
If you like to extract a cpio archive that contains hard linked
directories, you also need to specify -link-dirs in extract or
diff mode. This is needed because many cpio implementations
create buggy archives with respect to hard links. If star would
look for hard linked directories in all cases, it would detect
many pseudo hard links to directories. Use -link-dirs with care
if you extract cpio archives.
Note that not all filesystem allow to create hard links to
directories. Also note that even though a non-root user is able
detect and archive hard linked directories, all known operating
systems require the extraction to be done as root in order to be
able to create or remove hard links to directories. For this
reason its only recommended to use this option when doing accu‐
rate backups and when hard links to directories are expected.
When the option -link-dirs is not used and hard links to direc‐
tories are present, the appendant sub-tree will appear more than
once on the archive and star will print Linkcount below zero
warnings for non directory hard links inside the sub-tree.
list=filename
Read filenames for store/create/list/diff command from filename.
The file filename must contain a list of path names, each on a
separate line. This option implies the -D option. To force
star to descend directories, use the -dodesc option in this
case. See also the -X option.
Note that if list=- has been specified, it is no longer possible
to use the -find -exec primary.
-lowmem
Try to run with reduced memory requirements. This causes star
to default to 1 MB of FIFO memory. Instead of allocating memory
to hold the directory content and reading the directory at once,
star reads the directory name by name. This may cause star to
close the directory if it rans out of file descriptors because
of deeply nested directories. If a directory then does not sup‐
port telldir(3)/seekdir(3), star will fail.
-lzip run the input or output through a lzip pipe - see option -z
below.
-lzo run the input or output through a lzop pipe - see option -z
below.
-M, -xdev
Do not descend mount points. This is useful when doing backups
of complete file systems. See NOTES for more information.
-m Do not restore access and modification time. (Access time is
only available if star is reading star, xstar, xustar, exustar,
or pax archives). If star extracts other archive types, the -m
flag only refers to the modification time.
-match-tree
If in create mode a pattern does not match a directory, and
-match-tree has been specified, the whole directory tree is
excluded from the archive and from further directory scans. By
default, star excludes the directory but still recursively scans
the content of this directory as complex patterns could allow
files inside the directory tree to match. Using -match-tree
allows to efficiently exclude whole trees from scanning. This
helps to avoid scannings directory trees that are on remote file
systems or contain excessive bad blocks.
maxsize=#
Do not store files in tarfile if they are bigger than #. See
bs= for the possible syntax. By default, the number is multi‐
plied by 1024, so the value counts in units of kBytes. If the
size specifier ends with a valid multiplication character (e.g
'.' for bytes or 'M' for MB) the specified size is used as spec‐
ified and not multiplied by 1024. See bs= option for all possi‐
ble multipliers.
-meta In create mode, -meta causes star to archive all meta data of
the file (e.g. uid, permissions, ...) but not the file content.
In extract mode, it causes star to restore all meta data but not
the file content. In addition, in extract mode no plain file,
special file or directory will be created. Meta files are
needed to support incremental backups.
Warning: Do not try to extract star archives containing meta
files using other tar implementations if they are not aware of
the meta file extensions of star. Star tries to force all tar
implementations that are not standard compliant to abort. Star
also tries to make all non POSIX.1-2001 compliant tar implemen‐
tations unable to find a valid filename. However when other
POSIX.1-2001 aware tar implementations come up and don't know
about meta files, they will destroy files on disk.
The problems result from the only current fallback in the POSIX
standard that tells tar implementations to treat all unknown
file types as if they were plain files. As meta files are needed
for incremental backups, I am looking for people and companies
who like to support me to be able to add the meta file concept
to the POSIX.1-2005 standard.
-modebits
This options allows you to create tar archives that include more
than 12 bits from st_mode. Note this create tar archives that
violate POSIX but some tar implementations insist in reading
such nonstandard archives.
-multivol
Switch to multi volume mode. In multi volume mode, there will
be no logical EOF marker written to the end of a single tape. If
-multivol is used in read mode, a hard EOF on input (if not pre‐
ceded by a logical EOF) triggers a medium change operation.
Specifying -multivol tells star to split files across volumes if
needed. This way, a virtual archive is created that spans more
than one medium. Multi volume mode is needed whenever it is not
possible to split the archiving or extracting into several logi‐
cally independent tasks. This is true for e.g. incremental
dump/restore operations where inode numbers need to be traced
for the whole task.
When tsize=# has been specified, but star is not in multi volume
mode, files cannot be split across volumes.
When -multivol has been specified in create mode together with
tsize=# then a media change is initiated exactly after an amount
of tsize data has been written. When -multivol has been speci‐
fied in create mode and tsize=# has not been specified, then the
medium change is triggered by a EOT condition from writing the
medium. This allows to use media where the size cannot be known
in advance (e.g. tapes with build in compression); it does not
work if the EOT condition is not returned in sync with the
related write operation. For this reason, it is expected that
data buffering inside a device driver cannot be used.
Depending on the selected archive format, star writes a volume
header at the beginning of a new medium. This medium header
allows to verify the correct volume after a change during read
back. It is recommended to use the exustar format for best
results. In create mode, -multivol is only supported for ar‐
chives types that allow to write reliable multi volume header
information.
See tsize=# option for more information.
Note that -multivol is an interactive option that prevents star
from being used in non-interactive environments. If you like to
use it in a non-interactive environment, you need to specify
new-volume-script=script in addition in order to automate the
media change procedure.
newer=filename
Do not store files to tarfile if their modification time is not
newer than the modification time of filename. See -ctime option
for changing this behavior.
-newest
In conjunction with the list command this lists you only the
newest file in tarfile.
-newest_file
obsoleted by -newest-file
-newest-file
In conjunction with the list command this lists you only the
newest regular file in tarfile.
new-volume-script=script
Call script at end of each tape if in multi volume mode. If
this option is not in effect, star will ask the user to confirm
the volume change. The script is called with two parameters.
The first parameter is the next volume number and the second
parameter is the next archive file name.
-nodump
If this option is set, star will not dump files that have the
nodump flag set. Note that this currently only works on BSD-4.4
derivates and on Linux. On Linux, using this option will cause
a performance degradation (the system time increases by 10%)
because of the unlucky kernel interface.
-no-dirslash
Do not add a slash to the end of directory names if writing to
an archive. Historic tar archive formats did only allow to
specify plain files and hard links. Around 1980, BSD added a
feature to specify a directory on tape by adding a slash to the
end of the name. POSIX.1-1988 defined the first official tar ar‐
chive format that had a clean method to specify the type of a
directory. As old tar formats need the slash to recognize a
directory, -no-dirslash may not be used if archives should be
compatible with the old tar format.
-no_fifo
obsoleted by -no-fifo
-no-fifo
Don't use a fifo to optimize data flow from/to tarfile. Cur‐
rently the -fifo option is used as default. (This may be changed
at compile time.)
-no-fsync
Do not call fsync(2) for each file that has been extracted from
the archive. Using -no-fsync may speed up extraction on operat‐
ing systems with slow file I/O (such as Linux), but includes the
risk that star may not be able to detect extraction problems
that occur after the call to close(2). A typical cause for such
problems is a NFS file system that fills up before the buffer
cache is synced or a write error that occurs while the buffer
cache is synced. There may be other reasons. Use with extreme
care.
-nochown, -o
Do not restore owner and group of files. This may be used if
super user privileges are needed to overwrite existing files but
the local ownership of the existing files should not change.
-no-p Do not restore files and directories to their original permis‐
sions. This option is needed only if star is called by the
super user and the permissions should not be restored from the
archive. See also the -p option. The -p options has a higher
precedence than the -no-p option.
-no_statistics
obsoleted by -no-statistics
-no-statistics
Do not print statistic messages at the end of a star run.
-no-xheader
Do not create or extract POSIX.1-2001 extended headers. This
option may be used if you like to read an archive with broken
extended headers.
-not, -V
Invert the meaning of the pattern list. i.e. use those files
which do not match any of the pattern. Note that this option
only applies to patterns that have been specified via the pat‐
tern=pattern or pat=pattern option. Patterns specified as file
type arguments will not be affected.
-notarg, -pax-c
Match all file or archive members except those specified by the
pattern or file operands.
-nowarn
Do not print warning messages. This sometimes is useful to make
the output more readable (e.g. when hundreds of files that are
going to be extracted are not newer in the archive then on the
filesystem).
-numeric
Use the numeric user/group fields in the listing rather than the
default. The default allows to list the ASCII version of
user/group of the file and to extract the owners of the files
based on numeric values rather than the names. In create mode,
no user/groups names are put on the archive. The -numeric
option also applies when ACLs are going to be archived or
extracted.
-O Be compatible to old versions of tar. If star is invoked with
this option, star generates archives which are fully compatible
with old UNIX tar archives. If in extract mode, star ignores any
additional info in the headers. This implies neither that ar‐
chives generated with this option are binary equal with archives
generated by old tar versions nor that star is trying to compre‐
hend all bugs that are found in old tar versions. The bug in
old tar versions that cause a reversal of a space and a NULL
byte in the checksum field is not repeated. If you want to have
signed checksums you have to specify the -signed-checksum option
too. If you want directories not to be archived in order to be
compatible to very old historic tar archives, you need to spec‐
ify the -d option too.
This option is superseeded by the H=headertype option.
-o, -nochown
Do not restore owner and group of files. This may be used if
super user privileges are needed to overwrite existing files but
the local ownership of the existing files should not change.
-onull, -nullout
Do not actually write to the archive but compute and add the
sizes. This is useful when trying to figure out if a tape may
hold the current backup. Please only use the -onull option as
it is a similar option as used by the sdd(1) command.
-P Allow star to write a partial record as the last record. Nor‐
mally, star writes each record with the same size. This option
is useful on unblocked tapes i.e. cartridge tapes like QIC tapes
as well as with archives that are located in files. If you use
this option on local files, the size of the archive will be
smaller. If you use this option on cartridge tapes, is makes
sure that later - in extract mode - star will read up to the end
of file marker on the tape and the next call to star will read
from the next archive on the same tape.
-p Restore files and directories to their original permissions.
Without this option, they are created using the permissions in
the archive and the present umask(2). If star is called by the
super user, star behaves as if it has been called with the -p
option. See also -no-p option. If the archive contains Access
Control Lists (ACLs) in POSIX.1-2001 extended headers, star will
restore the access control lists from the archive for files if
the -acl option is specified. If the option -acl has not been
specified, ACLs are not restored at all.
pattern=pattern, pat=pattern
Set matching pattern to pattern. A maximum of 100 pattern=pat
options may be specified. As each pattern is unlimited in
length, this is no real limitation. If more than one pattern is
specified, a file matches if any of the specified pattern
matches. Patterns may be used in create mode to select or
exclude files from the list of file type arguments or the files
located in a sub tree of a file type argument directory. By
default, star scans the whole directory tree underneath a direc‐
tory that is in the argument list. This may be modified by using
the -match-tree option. In extract or list mode, all file type
arguments are interpreted to be select pattern and all option
type patterns may be either select or exclude patterns depending
on the presence or absence of the -not option. If you use file
type select patterns, they work exactly like the method used by
other (non pattern aware) tar(1) implementations. File type
select patterns do not offer pattern matching but allow to
restore subtrees. To extract a complete sub tree from the
directory dir with star using the pattern= option, use pattern=
dir/\* if you like to select a subtree by using the historic
method, use dir as file type argument. If you only like to
extract the directory itself, use dir/ as file type argument.
See manual page for match(1) for more details of the pattern
matcher. All patterns are selection patterns by default. To
make them exclude patterns, use the -not or the -V option.
pkglist=file
This is (for now) an internal interface for the Schily Source
Package System (sps). It only works in create mode and behaves
similar to the list= option, but it allows to overwrite the per‐
missions, the uid and gid values from the content of the
pkglist= file. Each line from the pkglist= file contains a file
name followed by the permission, a user name and a group name.
The permission is an octal character string. Each value that is
not used to overwrite the original values may be replaced by a
'?'. The fields are separated by spaces, so the pkglist= option
does not allow files that contain newline or space characters.
-pax-c, -notarg
Match all file or archive members except those specified by the
pattern or file operands.
-pax-H Follow symbolic links that have been encountered on the command
line. If the referenced file does not exist, the file informa‐
tion and type will be for the link itself. If the link is ref‐
erencing a file type that cannot be archived with the current
archive format, the file information and type will be for the
link itself.
-pax-i Do interactive renaming in a way that has been defined for POSIX
pax. Star will print the original filename and prompt for a
reply. If you type just RETURN, than the file is skipped. If
you type '.', then the original file name is retained. If you
type anything else, then this is taken as the new file name.
Note that -pax-i is an interactive option that prevents star
from being used in non-interactive environments.
-pax-L Follow symbolic links. If the referenced file does not exist,
the file information and type will be for the link itself. If
the link is referencing a file type that cannot be archived with
the current archive format, the file information and type will
be for the link itself.
-pax-ls
Switch listing format to the format defined for POSIX pax and
ls.
-pax-match
Allow file type arguments to be recognised as regular expres‐
sions in a way that has been defined for POSIX pax.
-pax-n Allow each pattern to match only once. If a pattern matches a
directors, then the whole sub tree matches the pattern.
-pax-p string
PAX style privileges string. Several characters (each has its
own meaning). The following characters are defined:
a Do not preserve file access times. This option is cur‐
rently ignored.
e Preserve the user ID, group ID, file mode bits. This is
equivalent to calling star -p -acl -xfflags.
m Do not preserve file modification times. This is cur‐
rently equivalent to calling star -m.
o Preserve the user ID and group ID. This is the default
for star if called as root.
p Preserve the file mode bits. This is equivalent to call‐
ing star -p.
-prinodes
Print inode numbers in verbose list mode if the archive contains
inode numbers.
-print-artype
Check the type of the archive, print the archive and compression
type on a single line and exit.
-qic24 Set tape volume size to 61440 kBytes. See tsize=# option for
more information.
-qic120
Set tape volume size to 128000 kBytes. See tsize=# option for
more information.
-qic150
Set tape volume size to 153600 kBytes. See tsize=# option for
more information.
-qic250
Set tape volume size to 256000 kBytes. See tsize=# option for
more information.
-qic525
Set tape volume size to 512500 kBytes. See tsize=# option for
more information.
-read0 Read null terminated file names from the file specified with the
list= option.
-refresh_old_files
obsoleted by -refresh-old-files
-refresh-old-files
-refresh
Do not create new files. Only already existing files may be
overwritten from tarfile if either newer versions are present in
the archive or if the -U flag is used. This allows to overwrite
files by more recent files from an archive that contains more
files than the target directory should contain. The option
-refresh-old-files is the same as the -refresh option.
-remove_first
obsoleted by -remove-first
-remove-first
Remove files before extraction. If this option is in effect,
star will remove files before extracting a file from the ar‐
chive. This is needed if you want to change the file type or if
you need to break a hard link. If you do not use either
-ask-remove or -force-remove together with -remove-first, this
option is useless and no files will be removed.
-remove_recursive
obsoleted by -remove-recursive
-remove-recursive
Remove files recursive. If removing of a file is permitted,
star will only remove files, specials and empty directories. If
this option is in effect, star will be allowed to recursively
removes non empty directories too.
-restore
switches star into true incremental restore mode. A file named
star-symtable and a directory named star-tmpdir is created in
the root directory of the file system where the extraction takes
place. If -restore has been specified, star behaves as if -xdot
has been specified too. See also level= option and section
INCREMENTAL BACKUPS for more information.
Note: Do not use the -restore option if you only like to restore
a single file or a list of selected files.
-S Do not store/create special files. A special files is any file
except plain files, symbolic links and directories. You need to
be super user to extract special files.
-s replstr
Modify file or archive member names named by a pattern according
to the substitution expression replstr. The format of replstr
is:
-s /old/new/[gp]
The old pattern may use regular expressions and the new string
may contain the special character '&'. The character '&' is sub‐
stituted by the string that matches the old pattern. The
optional trailing 'g' means global substitution. If 'g' is not
used, a substitution pattern is only used once on a name. If
the optional trailing 'p' is used, the substitution is printed
to standard error.
Up to 100 substitute options may be used. If more than one sub‐
stitute option has been specified, star will loop over all sub‐
stitute patterns until one matches.
If the name substitutes to the empty string, the file is
skipped.
-secure-links
Do not extract hard links or symbolic links if the link name
(the target of the link) starts with a slash (/) or if /../ is
contained in the link name. Tar archives containing such links
could be used to compromise the system. If they are unpacked
together with a lot of other files, this may not even be
noticed.
As the usability of a tar archiver would be limited if
-secure-links checking would be done by default, star makes link
checking optional.
If you unpacked a tar archive using the -secure-links and did
not get a security warning at the end of the star run, all files
and links have been extracted. If you get a warning, you should
unpack the archive a second time and specify the options -k, -w
and -nowarn in addition to the options used for the first run.
See SECURITY NOTES for more information.
-shm Use System V shared memory for fifo. Normally star is compiled
to use mapped /dev/zero pages for the fifo, if the operating
system supports this. If star is compiled to have both code for
mapped pages and for System V shared memory, star will use
shared memory instead of the default. If the -help menu doesn't
show the -shm flag you have no choice. When using System V
shared memory, you may have to raise the system's internal limit
for shared memory resources to get enough shared memory for
star.
-signed_checksum
obsoleted by -signed-checksum
-signed-checksum
Use signed chars to calculate checksums. This violates the tar
specs but old versions of tar derived from the seventh edition
of UNIX are implemented in this way. Note: Only filenames and
linknames containing chars with the most significant bit set may
trigger this problem because all other fields only contain 7 bit
ASCII characters, octal digits or binary zeroes.
-silent
Suppress informational messages like foobar is sparse.
-sparse
Handle files with holes effectively on store/create. Note that
sparse files may not be archived this way if the archive format
is tar, ustar, suntar, pax, or any cpio variant. On Solaris-2.3
... Solaris-2.5.1 there is a special ioctl() called _FIOAI that
allows root to get the allocation info more efficiently. On
Solaris 11 there is an enhanced lseek(2) call with addidional
whence values SEEK_HOLE and SEEK_DATA that allow to find holes
in an efficient way. Other operating systems lack support to
get the real allocation list and force star to scan the files to
look for blocks that only contain null characters. This may
star cause to assume more holes to be present than the number
that the file really contains.
-symlinks
This option tells star in extract mode to try to create a sym‐
link whenever a hardlink is encountered in the archive.
-T If the option file= or f= is omitted and the -T option is
present, star will use the device indicated by the TAPE environ‐
ment variable, if set.
tardumps=name
Set the file name for tar dump dates database to name. The
default name is /etc/tardumps. Use in combination with the
level= option to create true incremental dumps. See also -wtar‐
dumps option and section INCREMENTAL BACKUPS for more informa‐
tion.
-time Print timing info. See DIAGNOSTICS for more information.
-to_stdout
obsoleted by -to-stdout
-to-stdout
Extract files to stdout. This option may be used to extract
tarfiles containing tarfiles (see examples below).
-tpath Use this option together with the -t option or with -cv (verbose
create) to get only a list of the pathnames of the files in the
archive. This may be used in shell scripts to generate a name
list. If used together with the -diff option, star will only
print the names of the files that differ. A second run of star
may then be used to restore all files that had differences to
the archive. Use the list= option to specify the namelist in
this case.
tsize=#
Set tape volume size to # to enable multi volume tape support.
The value refers to the archive size without compression. See
bs= for the possible syntax. By default, the number is multi‐
plied by 512, so the value counts in units of 512 byte blocks.
If the size specifier ends with a valid multiplication character
(e.g '.' for bytes or 'M' for MB) the specified size is used as
specified and not multiplied by 512. With this option in
effect, star is able to archive filesystems that are bigger then
the tape size. If the option tsize=# without -multivol then no
file will be split across volumes and each volume may in theory
be read back separately. Files that do not fit on a single tape
may not be stored in this mode. If -multivol has been specified
in addition, star will split files when the maximum allowed tape
size has been reached. If the tape volume size is not a multi‐
ple of the tape block size, the tape volume size is silently
rounded down to a value that is a multiple of the tape block
size.
See -multivol option for more information.
-U Restore files unconditionally. By default, an older file from
the archive will not replace a corresponding newer file on disk.
umask=mask
Set star's umask to mask. This allows to control the permis‐
sions for intermediate directories that are created by star in
extract mode. See also -p option.
-v Increment verbose level by one. This normally results in more
output during operation. See also in the description for the -t
flag. Normally, star does its work silently. If the verbose
level is 2 or more and star is in create or update mode, star
will produce a listing to the format of the ls -l output.
-V, -not
Invert the meaning of the pattern list. i.e. use those files
which do not match any of the pattern. Note that this option
only applies to patterns that have been specified via the pat‐
tern=pattern or pat=pattern option. Patterns specified as file
type arguments will not be affected.
-version
Print version information and exit.
VOLHDR=name
Use name to generate a volume header.
-w Do interactive creation, extraction or renaming. For every file
that matches the list of patterns and that has a more recent
modification time in the tar archive (if in extract mode and the
-U option is not specified) star prints its name and asks:
get/put ? Y(es)/N(o)/C(hange name) :
You may answer either `N' for No or <Return> to skip this file.
If you answer `Y' the file is extracted or archived on tape with
its original name. If you answer `C', you are prompted for a
new name. This name is used for the filename on disk if star is
in extract mode or for the archive name if star is in create
mode.
See SECURITY NOTES for more information.
Note that -w is an interactive option that prevents star from being
used in non-interactive environments.
-wready
This option tells Star to wait up to two minutes for the drive
to become ready. It has been added as a hack for a bug in the
SunOS/Solaris st device driver. This driver has problems to
sense the loading time with Exabyte drives with factory set‐
tings. It also makes sense to use -wready if multiple remote
backups are made. In this case, the remote connection is closed
while the remote tape server is still writing a file mark. If
another remote backup is initiated before the old remote server
did finish to write the file mark, it would be impossible to
open the tape driver unless -wready is specified to tell star to
wait for the drive to become ready again.
-wtardumps
Tell star to update the file that contains the tar dump dates
data base if in dump mode. If the dump is not a full dump, the
tar dump dates data base file is not written. See also tar‐
dumps=name and -C option or INCREMENTAL BACKUPS section for more
information.
-X filename
Use the file filename as a file containing a list of path names
to be excluded from the store/create/list/diff operation. The
file filename must contain a list of path names, each on a sepa‐
rate line. Be careful with white space and note that path names
in the list may not contain new lines. Multiple -X options may
be used. Each argument must refer to a file containing path
names. The -X option has precedence before other options that
select files to be included in the operation. See also list=
option.
-xattr
-xattr-linux
Store and extract extended file attributes as found on Linux
systems. This option only makes sense when creating or extract‐
ing exustar archives as it is based on POSIX.1-2001 extended tar
headers.
The method used in the current implementation could be used to
store and extract extended file attributes from BSD too. Note
that the current implementation is not generic enough to cover
more general extended file attribute implementations as found on
Solaris. If star starts to implement a method that covers
extended file attributes on Solaris, the new method will be used
then -xattr has been specified and -xattr-linux will refer to
the old method. The method used with -xattr-linux may go away
in the future.
xdebug=#, xd=#
Set extended debug level to #.
-xdev, -M
Do not descend mount points. This is useful when doing backups
of complete file systems. See NOTES for more information.
-xdir Extract directories even if the corresponding directories on the
archive are not newer. This is useful when for some reason, the
directories are recorded after their content (see -dirmode
option), or when the permissions of some directories must be set
in any case. As the classical UNIX cpio program does not imple‐
ment delayed directory permission and time stamp setting, cpio
users often create archives in reverse order (directories past
their content). For this reason, it makes sense to use -xdir
while extracting cpio archives.
-xdot Unconditionally extract the first directory in the archive if
the name of this directory is either '.' or './'. This helps to
extract archives in an expected way if the target directory is a
newly created empty directory. As this directory is newer than
the top level directory in the archive, star would usually skip
this directory during extraction. The effect of this directory
is as if -xdir has been specified but is switched off after the
first directory has been found.
-xfflags
Store and extract extended file flags as found on BSD and Linux
systems. This option only makes sense when creating or extract‐
ing exustar archives as it is based on POSIX.1-2001 extended tar
headers. See NOTES section for problems with -xfflags on Linux
systems.
-xmeta Extract meta files as if they were files. Meta files in ar‐
chives are plain files that do not contain any content data in
the archive. They may be created by using the -meta option in
star's create mode. Existing files are not overwritten. If a
file is missing, a zero sized file is created. If the option
-meta is used together with the option -force-hole, missing
plain files are created as sparse empty files of the original
size.
-xz run the input or output through a xz pipe - see option -z below.
-Z run the input or output through a compress pipe - see option -z
below.
-z run the input or output through a gzip pipe. This is currently
a quick and dirty hack, that mainly will cover the most common
usage to compress the tar output if it is a file. No reblocking
will be done, so this option will currently only make sense on
plain files. As the -bz the -j the -Z and the -z option are non
standard, it makes sense to omit the -bz the -j the -Z and the
-z options inside shell scripts if you are going to extract a
compressed archive that is located inside a plain file as star
will auto detect compression and choose the right decompression
option to extract. The environment variable STAR_COMPRESS_FLAG
may be used to specify one option for gzip. If you want to
write write compressed archives to tape, you should use
star -c . | gzip | sdd ibs=4k obs=32k -fill of=/dev/rmt/1bn
or
star -c . | gzip | sdd ibs=4k obs=32k -fill ovsize=60m
of=/dev/rmt/1bn
if the tape can hold 60 MB.
INCREMENTAL BACKUPS
Star is able to back up file system in full and incremental mode. To
allow incremental backups, the file system must implement POSIX seman‐
tics.
To be more verbose:
· The filesystem needs to uniquely identify files by the two num‐
bers st_dev (The device ID of the device containing the file)
and st_ino (The file serial number). If a file is renamed,
these numbers need to be retained. Both numbers need to be a
cardinal scalar that is expressible in a decimal number.
· The filesystem needs to implement at least two time stamps,
st_mtime the file's last modification time and st_ctime the
file's last status change time. Both time stamps need to be
dealt with as documented by the POSIX standard. Both numbers
need to be a cardinal scalar that is expressible in a decimal
number.
· The filesystem needs to allow to rename files and directories by
either calling rename(2), or link(2) and unlink(2).
· The filesystem needs to honor and preserve the case of file
names.
The incremental backup method used by star depends on comparing the
time stamps of all files against the time of the last backup. Note that
this method only works correctly if the level 0 backup and all higher
level incrementals include the whole file system. As star archives all
inode meta data, star is able to detect renamed files by comparing the
inode numbers of all files while in incremental restore mode.
Detecting renamed files only works if star, while in backup mode, scans
the whole file system tree for each full and incremental backup. This
will work in case no files are excluded and the dump starts at the root
directory of a file system. In case that no files are renamed from
excluded parts to included parts, partial backups may be taken also.
Partial backups only make sense if a complete directory sub tree is
excluded (e.g. by using the pat= option) or if a partial backup starts
at a sub directory that is not the root directory of the file system.
To create a level 0 dump call:
star -c -xdev -sparse -acl -link-dirs level=0 -wtardumps \
f=archive-name -C /filestem-mount-point .
To create a level 1 dump call:
star -c -xdev -sparse -acl -link-dirs level=1 -wtardumps \
f=archive-name -C /filestem-mount-point .
Do not forget the dot at the end of the command line that specifies the
directory to start the operation.
Backups from live filesystems should be avoided. On operating systems
that support file system snapshots, backups should be made from a read-
only mount of a snapshot. Be careful that all files that have been cre‐
ated between setting up a snapshot and starting an incremental backup
may be missing from all backups unless the dumpdate=name option is
used.
If the system that is going to be backed up is not acting as a file
server, it makes sense to shut down all services that may result in
inconsistent file states before setting up the filesystem snapshot.
After the filesystem snapshot has been set up, the services may be
restarted.
If the the system that is going to be backed up is acting as a file
server, it may be that services on remote clients cause inconsistent
file states unless all such services that remotely access files are
shut down before the snapshot is set up.
Star includes options that help to deal with file system snapshots.
The following example backs up a file system on Solaris using a file
system snapshot:
echo > /tmp/snapstamp
mount -r `fssnap -F ufs -o \
backing-store=/var/tmp/EXPORT-NFS.snap /export/nfs` /mnt
star -c -xdev -sparse -acl -link-dirs level=0 -wtardumps \
f=archive-name dumpdate=/tmp/snapstamp \
fs-name=/export/nfs -C /mnt .
First a file with a current time stamp is created, then a snapshot for
/export/nfs is created and mounted on /mnt. The following star command
then creates a level 0 backup from the file system using the time the
snapshot was created and the original mount point of the file system
for /etc/tardumps and the archive header.
Note that if the backup is done on a live file system, it may be unre‐
liable. A typical problem problem in this context is caused by growing
log files. As growing files are not a real problem with backups, the
best way of dealing with growing files is to set up a star error con‐
trol file (see errctl= option) and to tell star to ignore growing
files.
BACKUP SCHEDULES
Full (level 0) dumps should be made on a regular base (e.g. once a
month). As a full dump may take a long time and takes a lot of tape,
it is wise to make higher level incremental dumps with shorter inter‐
vals. The next table shows a dump level list that may be used if
monthly full dumps take place:
Sun Mon Tue Wed Thu Fri
Week 1: 0 10 10 10 10 5
Week 2: 10 10 10 10 10 5
Week 3: 10 10 10 10 10 5
Week 4: 10 10 10 10 10 5
The level 10 dumps made between Monday and Friday accumulate all
changes made within the week. If you don't like this, use the following
backup schedule:
Sun Mon Tue Wed Thu Fri
Week 1: 0 20 30 40 50 5
Week 2: 10 20 30 40 50 5
Week 3: 10 20 30 40 50 5
Week 4: 10 20 30 40 50 5
Note that in this case, 7 dumps need to be restored if the a crash hap‐
pens at the worst case date (just before the Friday dump in week 2 or
later).
INCREMENTAL RESTORES
Incremental restores should be made to an empty file system (except for
the lost+found directory). Star is currently unable to perform incre‐
mental restores to a file system that contains active mount points.
The incremental restore procedure starts with restoring the last full
(level 0) dump. Then the latest incremental dump of each dump level
(with ascending order of dump levels) need to be restored.
Let us assume the first example from the section BACKUP SCHEDULES for
the backup schedule. If a disk crash happens before the Thursday dump
of week 3 has been made, the following restore procedure needs to be
applied:
level 0
starting with an empty disk, the full (level 0) dump from week 1
is restored.
level 5
after the level 0 restore has been finished, the level 5 dump
from Friday in week 2 is restored.
level 10
after the level 5 restore has been finished, the level 10 dump
from Wednesday in week 3 is restored.
The disk now contains the same files as it did when the level 10 dump
has been made on Wednesday of week 3.
To extract a level 0 dump call:
cd /filestem-mount-point
star -xpU -restore f=archive-name
This creates the directory star-tmpdir and the database star-symtable
in the root directory of the new file system. Subsequent restores with
higher level backups depend on these files.
To extract a level 1 (or higher) dump call:
cd /filestem-mount-point
star -xpU -restore f=archive-name
Note that the environment variable STAR_DEBUG exists, star does not
remove files with link count 1 that have been removed between incremen‐
tal dumps. These files are moved to the directory star-tmpdir. Before
you start to extract the next incremental, you need to remove all files
in star-tmpdir.
SYNCHRONIZING FILESYSTEMS
Star may be used to synchronize filesystem content. To do this, an
initial copy of the current content of the source filesystem needs to
be performed first.
To create an initial copy of a filesystem call:
star -c -xdev -sparse -acl -link-dirs level=0 -wtardumps \
-C /filestem-mount-point . | \
star -xpU -restore -C /extract-target-dir
In order to perform subsequent synchronization of the target filesystem
with the content of the source filesystem, a modified incremental
dump/restore procedure may be used.
To copy incremental content of a filesystem call:
star -c -xdev -sparse -acl -link-dirs level=1 -wtardumps \
-cumulative -C /filestem-mount-point . | \
star -xpU -restore -C /extract-target-dir
Note that like with backups in general, copies from a live filesystem
should be avoided. On operating systems that support file system snap‐
shots, copies should be made from a read-only mount of a snapshot. Be
careful that all files that have been created between setting up a
snapshot and starting an incremental copy may be missing from all
copies unless the dumpdate=name option is used.
See section INCREMENTAL BACKUPS to learn how to modify the command line
in case file system snapshots are used.
SIGNALS
If star handles a signal, it first prints the statistics. Star handles
the following signals:
SIGINT usually generated by ^C from the controlling tty. Upon
receipt of a SIGINT, star prints statistics and exits. If in
create mode i.e. storing files to archive, star finishes with
the current file to ensure that no partial file is written to
the archive, write an eof record and then exits.
SIGHUP not to be generated from a tty. The actions are the same as
upon receipt of a SIGINT.
SIGQUIT usually generated by ^\ from the controlling tty. Upon
receipt of a SIGQUIT, star prints statistics and continues
with the current operation. This is useful to watch the
progress of the current operation.
EXIT STATUS
The following exit values are returned:
0 All files were processed successfully.
-3 / 253
Star has been called with the option -e, or the errctl= option
has been used to mark the current error fatal.
-2 / 254
One or more files could not be processed successfully.
-1 / 255
Command line parsing error.
>0 Other positive exit codes: The errno of the call that caused the
fatal error.
EXAMPLES
To get a listing in a way similar to ls -l one might use:
example% star -tv f=/dev/rmt/1bn
The same command as listed above in a POSIX tar command line syntax
compliant way is:
example% star tvf /dev/rmt/1mbn
To copy the directory tree in /home/someuser to the directory /home/fs
use:
example% (cd /home/someuser; star -c .) | (cd /home/fs ; star -xp)
or by using the change directory option of star:
example% star -c -C /home/someuser . | star -xp -C /home/fs
Note that both examples above are not the optimum way to copy a direc‐
tory tree. A more efficient way to copy a directory tree is to use the
-copy option.
example% star -copy -p -xdot -C /home/someuser . /home/fs
To copy a file tree including the Access Control List entries for all
files and to correctly copy sparse (holey) files use:
example% star -copy -p -xdot -acl -sparse -C /home/someuser . /home/fs
To compare the content of a tape to the filesystem one might use:
example% star -diff -v f=/dev/rmt/1bn
To compare two directory trees one might use:
example% star -c . | star -C todir -diff -v diffopts=!times
or better by using a method similar to the -copy method above:
example% star -c -diff -v diffopts=!times -C fromdir . todir
To compare all properties of two file trees, use:
example% star -c -diff -vv -dump -acl -sparse -C fromdir . todir
To extract a backup of the /usr tree without all files residing below
/usr/openwin one might use:
example% star -xp -V pat=openwin/\* f=/dev/rmt/1bn
To extract all .c files to src, all .o files to obj and all other files
to /tmp one might use:
example% star -xp -C src '*.c' -C obj '*.o' -C /tmp '*' f=/dev/rmt/1bn
To extract files from a zipped tar archive that is located on a read
only filesystem e.g. a CD while having the shell's working directory on
the CD one might use:
example% star -zxp -C /tmp f=star-1.1.tar.gz
to extract the files from the tar archive to the /tmp directory.
To backup a list of files generated by the find(1) command:
example% find . find_options -print | star -c list=- f=/dev/rmt/1bn
Note that this does not work if the file names from output of the find
command include new line characters.
To extract a tarfile that contains a tarfile one might use:
example% star -x -to-stdout f=/dev/rmt/1bn pat=pat | star -xp
Pat, in this case should match the tarfile in the tarfile on tape that
should be extracted.
To make a backup of the root filesystem to a tape drive connected to a
remote machine, one might use:
example# cd /
example# star -cM fs=128m bs=63k f=tape@remotehost:/dev/rmt/1bn .
You need a line in /etc/passwd like the following to enable this:
tape:NP:60001:60001:Tape:/etc/tapehome:/opt/schily/sbin/rmt
And a .rhosts file in /etc/tapehome to allow remote connections from
the appropriate hosts. Make sure that the file /etc/default/rmt exists
and allows remote access to the requested tape drive.
To use a ssh(1) connection for a backup to a remote tape server, one
might use:
example# env RSH=/usr/bin/ssh star -cM fs=128m bs=63k
f=tape@remotehost:/dev/rmt/1bn .
To repair a corrupted filesystem for which no recent backup exists, do
the following:
example# fsck -y /filesys
example# mount /filesys
example# cd /filesys
example# star -xpk f=/dev/rmt/1bn
example# mt -f /dev/rmt/1bn rewind
example# star -diff -v diffopts=!times f=/dev/rmt/1bn
Now check the differences and decide whether to restore additional
files. This may be done by generating a list containing the needed
filenames and using the list= option or by using the interactive mode
(see -w option).
If you want a list that only contains all filenames from files with
differences you may use:
example# star -diff -tpath diffopts=!times f=/dev/rmt/1bn
If you are looking for files that changed the type or the access per‐
mission because this is a common case on still corrupted files, use:
example# star -diff -tpath diffopts=type,perm f=/dev/rmt/1bn
If you like to archive all directories only that are part of the direc‐
tory tree under ".", use:
example# star -c f=archive-name -find . -type d
If you like to archive all files as owner root and group root and make
all files world readable in the archive, use:
example# star -c f=archive-name -find . -chown root -chgrp root
-chmod o+r
If you like to list all files in an archive in a way like sfind(1),
instead of the way used by star, use:
example# star -t f=archive-name -find . -ls -false
ENVIRONMENT
STAR_COMPRESS_FLAG
If you like star to always create compressed files that use max‐
imum compression, you may set the environment variable STAR_COM‐
PRESS_FLAG to -9.
STAR_DEBUG
If this environment variable is present, star will not remove
temporary files from ./star-tmpdir. The files in this directory
are files that have been removed by users before the last incre‐
mental dump did take place on the master filesystem.
STAR_FIFOSIZE
If you like to by default let star use a different fifo size,
set this environment variable to the desired size.
TAPE Unlike other tar(1) implementations, star defaults to use
stdin/stdout for the archive. If you like star to use the file
name from the TAPE environment instead, you need to specify the
-T option too.
RSH If the RSH environment is present, the remote connection will
not be created via rcmd(3) but by calling the program pointed to
by RSH. Use e.g. RSH=/usr/bin/ssh to create a secure shell
connection.
Note that this forces star to create a pipe to the rsh(1) pro‐
gram and disallows star to directly access the network socket to
the remote server. This makes it impossible to set up perfor‐
mance parameters and slows down the connection compared to a
root initiated rcmd(3) connection.
See BUGS section for more information.
RMT If the RMT environment is present, the remote tape server will
not be the program /etc/rmt but the program pointed to by RMT.
Note that the remote tape server program name will be ignored if
you log in using an account that has been created with a remote
tape server program as login shell.
FILES
/etc/default/star
Default values can be set for the following options in
/etc/default/star. For example: CDR_FIFOSIZE=64m
STAR_FIFOSIZE
Sets the default size of the FIFO (see also fs=# option).
STAR_FIFOSIZE_MAX
Sets the maximum size of the FIFO (see also fs=# option).
Setting STAR_FIFOSIZE_MAX in /etc/default/star allows to
overwrite global values from backup scripts for machines
with less memory.
archive0=
archive1=
archive2=
archive3=
archive4=
archive5=
archive6=
archive7=
Archive entries for the -[0..7] option.
A correct archive?= line has 3..4 space separated
entries. The first is the device entry (e.g. ar‐
chive0=/dev/tape). The second is the blocking factor in
512 byte units. The third is the maximum media size in
1024 byte units. If this entry contains a 0, then the
media size is unlimited. The fourth entry is optional.
If it contains a 'n' or a 'N', then the archive device is
not a tape.
Examples:
archive0=/dev/tape 512 0 y
archive1=/dev/fd0 1 1440 n
archive2=/dev/rmt/0mbn 512 0
If the default file does not need to be shared with the
tar program from Solaris, any number may be used like a
generic size option like bs=.
Example:
archive0=/dev/tape 256k 40G y
/etc/tardumps
The default name for the dump level archive. The default name is
used whenever the tardumps=name option has not been specified.
The file is written or updated when -wtardumps is used.
The file holds one or more lines, each specifying a dump level
entry. Each dump level entry starts with a mount point name
followed by a TAB and one or more spaces, followed by the deci‐
mal dump level, a space and the dump time.
If the dump level is directly followed by a 'P', then the dump
refers to a partial dump (a dump that does not include the whole
filesystem).
The dump time itself includes the decimal representation of the
UTC seconds since Jan 01 1970, a space and the textual local
time representation of the dump time.
The numerical decimal dump time representation may be followed
by a dot and a sub second value. The textual local time repre‐
sentation is for informational use by humans only and not evalu‐
ated by star.
./star-symtable
Contains a database that is needed in incremental restore mode.
./star-symdump
Contains an intermediate dump of restore database after a fatal
error condition was met during an incremental restore operation.
./star-tmpdir
Is the temporary directory that is used as intermediate file
storage by star if in incremental restore mode.
./star-lock
Is a lock file created by star when doing an incremental
restore. If this file is present, it prevents star from running
another incremental restore operation. This helps to avoid more
than one restore operation at a time (e.g. from a cron script).
/dev/tty
Is used for the intercative user interface.
SEE ALSOspax(1), tar(1), cpio(1), pax(1), rcp(1), mt(1), rmt(8), match(1),
dd(1), sdd(1), rsh(1), ssh(1), star(4), rcmd(3), fssnap(1m)DIAGNOSTICS
star: f records + p bytes (total of x bytes = d.nnk).
The number of full records, the number of bytes in partial records and
the total amount of data in KBytes.
star: Total time x.yyysec (z kBytes/sec)
The time used and the transfer speed from/to the archive.
If there have been non fatal errors during the archive processing, star
will display a delayed error summary before exiting.
NOTES
The command line syntax for the tar command (as defined in SUSv2 -
UNIX-98) deviates from the command line syntax defined for all other
commands. While the POSIX command line syntax requests all options to
start with a dash (-) and allows to either write options separately or
combined (in case of boolean flags), the tar command line syntax
requires all options to be combined into a single string that does not
start with a dash. Star by default assumes a command line syntax like
a typical POSIX command and includes a compatibility mode that allows
to specify a command line syntax as documented for the UNIX-98 tar com‐
mand. If you believe that you found a bug in the way star parses the
command line, please first check your command line for correctness
before you make a bug report for star.
If you like to write portable shell scripts that call tar, use the
UNIX-98 tar command line syntax (i.e. a single option string and no
dash), choose the commands and options from the following set of char‐
acters ( rxtuc vxfblmo ) and check the shell script with both, your
local tar and star for correct behavior. It you expect the script to
call gnutar, do not include the -o option as gnutar implements this
option in a way that violates UNIX-98.
Star strips leading ./ sequences from pathnames. This lets star in many
cases store longer pathnames than other implementations.
The POSIX.1-1988 method (ustar format) of storing files with pathnames
that are longer than 100 chars has some limitations:
The name field (100 chars) an inserted slash (`/') and the pre‐
fix field (155 chars) produce the pathname of the file. When
recreating the original filename, name and prefix are concate‐
nated, using a slash character in the middle. If a pathname does
not fit in the space provided or may not be split at a slash
character so that the parts will fit into 100 + 155 chars, the
file may not be archived. Linknames longer than 100 chars may
not be archived too.
The star, xstar, xustar, exustar, pax, and gnutar archive formats don't
have these limitations. While gnutar uses a method that makes it impos‐
sible for other tar implementations (except star) to restore filenames
that are longer than 100 chars, the xstar, xustar, exustar and pax ar‐
chive format uses a method that allows an POSIX.1-1988 compliant way of
storing filenames, if the POSIX method would allow this. When the ar‐
chive format is xustar, exustar or pax very long filenames are stored
using extended headers from the POSIX.1-2001 standard.
Some buggy tar implementations will generate incorrect filenames during
a restore operation if the archive contains pathnames or linknames of
exactly 100 chars length.
Star adds a tar signature in the last four bytes of each tar header if
the archive format is star or xstar. This is no problem with the star
archive format as it is an extension of the old pre POSIX.1-1988 tar
format. On the other side, the xstar archive format claims to be as
POSIX.1-1988 compliant as possible. Inserting this tar signature is a
minor deviation from the standard that has the last 12 bytes of each
header reserved for future use. On the other side, tar implementations
such as some pax implementations that only compute checksums on the
first 500 bytes of the header are violating the standard that requests
the checksum to be computed on all 512 bytes of the tar header. All tar
implementations that are 100% Posix compliant will be able to extract
xstar archives as long as no new standard is defined that claims the
last 12 bytes of the header for a different use. But then the ustar
version number should be changed from `00' to `01'. Now, that the
POSIX-2001 standard has been accepted, it is even predictable that all
extensions to the standard tar format will go into the POSIX.1-2001
extended headers which are extensible to include any feature without
future limitation. The only known tar implementation that also uses
the last 12 bytes of the tar header is Sun's tar which uses these 12
bytes for files that are split over several archives. Such archives
created by Sun's tar are not readable by the buggy pax implementation
too. The Sun extension is not incompatible to the star signature
because Sun expects an octal number at the beginning of the 12 byte
field which is a null character in the star case.
Star uses these four bytes since 1985 without problems. If you need a
100% POSIX.1-1988 and 100% POSIX.1-2001 compliant tar archive, you may
use the xustar, exustar or the pax archive format. The probability of
falsely detecting other tar formats as xustar or exustar format however
is higher.
There is no way to ask for the n-th occurrence of a file.
The way EOF is handled by star differs, whether the fifo is in effect
or not. If the fifo is not used, star stops reading the archive if it
encounters a logical EOF record in the archive. If the fifo is used,
star may read until the fifo is full or until the real EOF mark on tape
is reached. How much data star actually reads depends on the time when
the star foreground process sends a fifo shutdown signal to the back‐
ground fifo read process.
Gnu tar often creates tar archives with incorrect logical EOF marks.
The standard requires two blocks that are completely zeroed, whereas
gnutar often only adds one of them.
Old versions of tar found on SYSVr3 and earlier cannot read tar ar‐
chives with a blocksize greater than 10 kBytes.
The method of storing sparse files currently used with the star and
xstar format is not guaranteed to be used in later versions of star.
If the author decides to change this method, later versions of star may
not be able to restore sparse files from tar archives made by the cur‐
rent version of star.
Some tar implementations violate the standard in using only the first
500 Bytes of the header for checksum computation. These tar implementa‐
tions will not accept star and xstar type tar archives.
Sun's Solaris 2.x tar implementation violates the Posix standard. Tar
archives generated by star cause Sun's tar to print tar: impossible
file type messages. You may ignore these messages.
Gnutar's dumpdirs are non standard and are currently not implemented.
If gnutar archives sparse files with more than four holes, it produces
archives that violate the standard in a way that prevents other tar
implementations to read these archives. Star knows about that and is
able to handle these gnutar archives.
The filetype N (LF_NAMES) from gnutar (an obsolete method of storing
long names) will never be implemented.
Note that on operating systems (like DOS) that do not implement real
pipes, star implements compression via a temporary file. Using com‐
pression thus is limited by the maximum file size and the available
disk space.
The extended file flags implementation (see -xfflags option) on Linux
is buggy by design. In order to retrieve the needed information, every
file needs to be opened. If the /dev directory is included in create
mode, every possible driver will be loaded which may hang the system
for a long time. In the worst case, unwanted side effects from opening
devices (such as causing tape drives to rewind the media) may be
caused.
SECURITY NOTES
If you unpack a tar archive in a non empty directory, any file in that
directory may be overwritten unless you specify the -k option. If the
archive contains symbolic links or hard links, star may even overwrite
files outside the current directory. If the directory where the ar‐
chive is been unpacked is not empty and contains contains symbolic
links or hard links to directories outside that directory, star may
also overwrite files outside the current directory. As many other com‐
mands, star usually has all possible permissions when run as root.
Unpacking archives as root thus may have fatal results to any file on
your system. Be very careful when you try to extract an archive that
has not been created by you. It is possible to create hand crafted tar
archives that may overwrite critical files (like /etc/passwd) on your
system. In addition all tar archives that have been created with the
list= option and tar archives where the C= option was not specified
before all file type arguments may be critical.
A good advise is to extract all doubtful archives as non root in an
empty directory and to specify the -secure-links option. If you get a
warning, you should unpack the archive a second time and specify the
options -k, -w and -nowarn in addition to the options used for the
first run.
SUID NOTES
If star is installed suid root, star is able to make connections to
remote archives for non root users. This is done by using the rcmd(3)
interface to get a connection to a rmt(8) server.
Star resets its effective uid back to the real user id immediately
after setting up the remote connection to the rmt server and before
opening any other file.
If star has not been installed suid root and not called by root, it
will try to create the remote connection via rsh(1) or ssh(1) (in case
the environment RSH has been set to ssh). Note that in this case, the
throughput to the remote tape server will be much lower than with a
connection that has been initiated via rcmd(3).
LIMITATIONS
If star is running on a large file aware platform, star is able to han‐
dle files up to 8 GB in a mode that is compliant to the POSIX.1-1988
ustar format. With a nonstandard star specific extension, up to 95 bits
may be used to code the filesize. This will handle files up to
200,000,000 TB. With the new POSIX.1-2001 extended headers used by the
xustar, exustar and pax format, any filesize may be archived.
BUGS
The fact that the -f option has to be implemented in a way that is com‐
patible with old tar implementations gives several problems. The
options -fifostats, -force-hole, -force-remove and -fifo interfere with
the -f option and the fact that they exist prevents users from using
filenames like e.g. ifo using the traditional way where the filename
directly follows the string -f without any space between the option
name and the file name. However, there is no problem to use a file
named ifo by by calling -f ifo, f=ifo, -f=ifo or -f= ifo. Be careful
not to make typos with the above options. The result could be that a
file is created as a result of the mistyped option.
There is currently no way to set the fifo lowwater and highwater marks.
There is currently no way to automatically delete files in the target
file tree if they are obsolete. Star should implement something simi‐
lar to gnutar's dumpdirs.
If not invoked by the super user star may not be able to extract files
if they reside in read only directories.
Star is not able to make a complete backup of a filesystem if files are
hidden by a mount that is in effect on a directory of this filesystem.
This may be avoided in case of the ufs filesystem if the backup is made
off a ufs snapshot (see the man page for fssnap(1m) It could be avoided
for any filesystem if the loopback filesystem had an option that tells
lofs not to traverse mountpoints.
For now (late 2002), we know that the following programs are broken and
do not implement signal handling correctly:
rsh on SunOS-5.0...SunOS-5.9
ssh from ssh.com
ssh from openssh.org
Sun already did accept a bug report for rsh(1)/ssh(1). Openssh.org
accepted and fixed a bug for their implementation of ssh(1).
If you use star to create a remote connection via an unfixed rsh(1) or
ssh(1), be prepared that terminal generated signals may interrupt the
remote connection.
HISTORY
Star was first created in 1982 to extract tapes on a UNIX clone that
had no tar command. In 1985 the first fully functional version has
been released as mtar.
When the old star format extensions have been introduced in 1985, it
was renamed to star (Schily tar). In 1994, Posix 1003.1-1988 exten‐
sions were added and star was renamed to star (Standard tar).
AUTHOR
Joerg Schilling
Seestr. 110
D-13353 Berlin
Germany
Mail bugs and suggestions to:
schilling@fokus.fraunhofer.de or js@cs.tu-berlin.de or
joerg@schily.isdn.cs.tu-berlin.de
Joerg Schilling 11/04/12 STAR(1)
