SYSRC(8) BSD System Manager's Manual SYSRC(8)NAMEsysrc — safely edit system rc files
SYNOPSISsysrc [-dDeFhinNqvx] [-f file] [-j jail | -R dir] name[=value] ...
sysrc [-dDeFhinNqvx] [-f file] [-j jail | -R dir] -a | -A
DESCRIPTION
The sysrc utility retrieves rc.conf(5) variables from the collection of
system rc files and allows processes with appropriate privilege to change
values in a safe and effective manner.
The following options are available:
-a Dump a list of all non-default configuration variables.
-A Dump a list of all configuration variables (incl. defaults).
-d Print a description of the given variable.
-D Show default value(s) only (this is the same as setting RC_CONFS
to NULL or passing `-f' with a NULL file-argument).
-e Print query results as ‘var=value’ (useful for producing output
to be fed back in). Ignored if -n is specified.
-f file Operate on the specified file(s) instead of the files obtained
by reading the ‘rc_conf_files’ entry in the RC_DEFAULTS file.
This option can be specified multiple times for additional
files.
-F Show only the last rc.conf(5) file each directive is in.
-h Print a short usage message to stderr and exit.
--help Print a full usage statement to stderr and exit.
-i Ignore unknown variables.
-j jail The jid or name of the jail to operate within (overrides ‘-R
dir’; requires jexec(8)).
-n Show only variable values, not their names.
-N Show only variable names, not their values.
-q Quiet. Ignore previous occurrences of -v flag.
-R dir Operate within the root directory (‘dir’) rather than (‘/’).
-v Verbose. Print the pathname of the specific rc.conf(5) file
where the directive was found.
-x Remove variable(s) from specified file(s).
This utility works similar to sysctl(8). It shares the `-e' and `-n'
options (detailed above) and also has the same ‘name[=value]’ syntax for
querying/setting configuration options.
However, while sysctl(8) serves to query/modify MIBs in the entrant ker‐
nel, sysrc instead works on values in the system rc.conf(5) configuration
files.
The list of system configuration files is configured in the file
‘/etc/defaults/rc.conf’ within the variable ‘rc_conf_files’, which by-
default contains a space-separated list of pathnames. On all FreeBSD
systems, this defaults to the value "/etc/rc.conf /etc/rc.conf.local".
Each pathname is sourced in-order upon startup. It is in the same fash‐
ion that sysrc sources the configuration files before returning the value
of the given variable.
When supplied a variable name, sysrc will return the value of the vari‐
able. If the variable does not appear in any of the configured
‘rc_conf_files’, an error is printed and error status is returned.
When changing values of a given variable, it does not matter if the vari‐
able appears in any of the ‘rc_conf_files’ or not. If the variable does
not appear in any of the files, it is appended to the end of the first
pathname in the ‘rc_conf_files’ variable. Otherwise, sysrc will replace
only the last-occurrence in the last-file found to contain the variable.
This gets the value to take effect next boot without heavily modifying
these integral files (yet taking care not to allow the file to grow
unwieldy should sysrc be called repeatedly).
ENVIRONMENT
The following environment variables are referenced by sysrc:
RC_CONFS Override default ‘rc_conf_files’ (even if set to NULL).
RC_DEFAULTS Location of ‘/etc/defaults/rc.conf’ file.
DEPENDENCIES
The following standard commands are required by sysrc:
awk(1), cat(1), chmod(1), env(1), grep(1), jls(1), mktemp(1), mv(1),
rm(1), sh(1), stat(1), tail(1), chown(8) and jexec(8).
FILES
/etc/defaults/rc.conf
/etc/rc.conf
/etc/rc.conf.local
EXAMPLES
Below are some simple examples of how sysrc can be used to query certain
values from the rc.conf(5) collection of system configuration files:
sysrc sshd_enable
returns the value of $sshd_enable, usually YES or NO.
sysrc defaultrouter
returns IP address of default router (if configured).
Working on other files, such as crontab(5):
sysrc-f /etc/crontab MAILTO
returns the value of the MAILTO setting (if configured).
In addition to the above syntax, sysrc also supports inline sh(1) PARAME‐
TER expansion for changing the way values are reported, shown below:
sysrc 'hostname%%.*'
returns $hostname up to (but not including) first `.'.
sysrc 'network_interfaces%%[$IFS]*'
returns first word of $network_interfaces.
sysrc 'ntpdate_flags##*[$IFS]'
returns last word of $ntpdate_flags (time server address).
sysrc usbd_flags-"default"
returns $usbd_flags or default if unset or NULL.
sysrc cloned_interfaces+"alternate"
returns alternate if $cloned_interfaces is set.
sysrc '#kern_securelevel'
returns length in characters of $kern_securelevel.
sysrc 'hostname?'
returns NULL and error status 2 if $hostname is unset (or if set,
returns the value of $hostname with no error status).
sysrc 'hostname:?'
returns NULL and error status 2 if $hostname is unset or NULL (or
if set and non-NULL, returns value without error status).
LIMITATIONS
The sysrc utility presently does not support the ‘rc.conf.d’ collection
of system configuration files (which requires a service name to be known
during execution).
This will be corrected by a future enhancement.
SEE ALSOjls(1), rc.conf(5), jail(8), jexec(8), rc(8), sysctl(8)HISTORY
A sysrc utility first appeared in FreeBSD 9.2.
AUTHORS
Devin Teske ⟨dteske@FreeBSD.org⟩
THANKS TO
Brandon Gooch, Garrett Cooper, Julian Elischer, Pawel Jakub Dawidek,
Cyrille Lefevre, Ross West, Stefan Esser, Marco Steinbach, and Jilles
Tjoelker for suggestions and help.
BSD Jul 5, 2013 BSD
