STAPRUN(8)STAPRUN(8)NAMEstaprun - systemtap runtime
SYNOPSISstaprun [ OPTIONS ] MODULE [ MODULE-OPTIONS ]
DESCRIPTION
The staprun program is the back-end of the Systemtap tool. It expects
a kernel module produced by the front-end stap tool.
Splitting the systemtap tool into a front-end and a back-end allows a
user to compile a systemtap script on a development machine that has
the kernel development tools (needed to compile the script) and then
transfer the resulting kernel module to a production machine that
doesn't have any development tools installed.
Please refer to stappaths (7) for the version number, or run rpm -q
systemtap (fedora/red hat) apt-get -v systemtap (ubuntu)
OPTIONS
The staprun program supports the following options. Any other option
prints a list of supported options.
-v Verbose mode.
-V Print version number and exit.
-w Suppress warnings from the script.
-u Load the uprobes.ko module.
-c CMD Command CMD will be run and the staprun program will exit when
CMD does. The '_stp_target' variable will contain the pid for
CMD.
-x PID The '_stp_target' variable will be set to PID.
-o FILE
Send output to FILE. If the module uses bulk mode, the output
will be in percpu files FILE_x(FILE_cpux in background and bulk
mode) where 'x' is the cpu number. This supports strftime(3)
formats for FILE.
-b BUFFER_SIZE
The systemtap module will specify a buffer size. Setting one
here will override that value. The value should be an integer
between 1 and 4095 which be assumed to be the buffer size in MB.
That value will be per-cpu if bulk mode is used.
-L Load module and start probes, then detach from the module leav‐
ing the probes running. The module can be attached to later by
using the -A option.
-A Attach to loaded systemtap module.
-C WHEN
Control coloring of error messages. WHEN must be either "never",
"always", or "auto" (i.e. enable only if at a terminal). If the
option is missing, then "auto" is assumed. Colors can be modi‐
fied using the SYSTEMTAP_COLORS environment variable. See the
stap(1) manual page for more information on syntax and behav‐
iour.
-d Delete a module. Only detached or unused modules the user has
permission to access will be deleted. Use "*" (quoted) to delete
all unused modules.
-D Run staprun in background as a daemon and show it's pid.
-R Rename the module to a unique name before inserting it.
-r N:URI
Pass the given number and URI data to the tapset functions re‐
mote_id() and remote_uri().
-S size[,N]
Sets the maximum size of output file and the maximum number of
output files. If the size of output file will exceed size ,
systemtap switches output file to the next file. And if the num‐
ber of output files exceed N , systemtap removes the oldest out‐
put file. You can omit the second argument.
-T timeout
Sets maximum time reader thread will wait before dumping trace
buffer. Value is in ms, default is 200ms. Setting this to a high
value decreases number of stapio wake-ups, allowing deeper sleep
for embedded platforms. But it impacts interactivity on terminal
as traces are dumped less often in case of low throughput.
There is no interactivity or performance impact for high
throughput as trace is dumped when buffer is full, before this
timeout expires.
var1=val
Sets the value of global variable var1 to val. Global variables
contained within a module are treated as module options and can
be set from the staprun command line.
ARGUMENTS
MODULE is either a module path or a module name. If it is a module
name, the module will be looked for in the following directory (where
'VERSION' is the output of "uname -r"):
/lib/modules/VERSION/systemtap
Any additional arguments on the command line are passed to the module.
One use of these additional module arguments is to set the value of
global variables declared within the module.
$ stap -p4 -m mod1 -e 'global var1="foo"; probe begin{printf("%s\n",
var1); exit()}'
Running this with an additional module argument:
$ staprun mod1.ko var1="HelloWorld"
HelloWorld
Spaces and exclamation marks currently cannot be passed into global
variables this way.
EXAMPLES
See the stapex(3stap) manual page for a collection of sample scripts.
Here is a very basic example of how to use staprun. First, use stap to
compile a script. The stap program will report the pathname to the re‐
sulting module.
$ stap -p4 -e 'probe begin { printf("Hello World!\n"); exit() }'
/home/user/.systemtap/cache/85/stap_8553d83f78c_265.ko
Run staprun with the pathname to the module as an argument.
$ staprun /home/user/.systemtap/cache/85/stap_8553d83f78c_265.ko
Hello World!
MODULE DETACHING AND ATTACHING
After the staprun program installs a Systemtap kernel module, users can
detach from the kernel module and reattach to it later. The -L option
loads the module and automatically detaches. Users can also detach
from the kernel module interactively by sending the SIGQUIT signal from
the keyboard (typically by typing Ctrl-\).
To reattach to a kernel module, the staprun-A option would be used.
FILE SWITCHING BY SIGNAL
After staprun launched the stapio program, users can command it to
switch output file to next file when it outputs to file(s) (running
staprun with -o option) by sending a SIGUSR2 signal to the stapio
process. When it receives SIGUSR2, it will switch output file to new
file with suffix .N where N is the sequential number. For example,
$ staprun-o foo ...
outputs trace logs to foo and if it receives SIGUSR2 signal, it switch‐
es output to foo.1 file. And receiving SIGUSR2 again, it switches to
foo.2 file.
SAFETY AND SECURITY
Systemtap, in the default kernel-module runtime mode, is an administra‐
tive tool. It exposes kernel internal data structures and potentially
private user information. See the stap(1) manual page for additional
information on safety and security.
To increase system security, users of systemtap must be root, or in the
staprun group in order to execute this setuid staprun program. A user
may select a particular privilege level with the stap --privilege= op‐
tion, which staprun will later enforce.
stapdev
Members of the stapdev group can write and load script modules
with root-equivalent privileges, without particular security
constraints. (Many safety constraints remain.)
stapsys
Members of the stapsys group have almost all the privileges of
stapdev, except for guru mode constructs.
staprun
Members only of the stapusr group may any-privileged modules
placed into the /lib/modules/VERSION/systemtap by the system ad‐
ministrator.
staprun
Members only of the stapusr group may also write and load low-
privilege script modules, which are normally limited to manipu‐
lating their own processes (and not the kernel nor other users'
processes).
Part of the privilege enforcement mechanism may require using a stap-
server and administrative trust in its cryptographic signer; see the
stap-server(8) manual page for a for more information.
FILES
/lib/modules/VERSION/systemtap
If MODULE is a module name, the module will be looked for in
this directory. Users who are only in the 'stapusr' group can
install modules located in this directory. This directory must
be owned by the root user and not be world writable.
SEE ALSOstap(1), stapprobes(3stap), stap-server(8), stapdyn(8), stapex(3stap)BUGS
Use the Bugzilla link of the project web page or our mailing list.
http://sourceware.org/systemtap/, <systemtap@sourceware.org>.
STAPRUN(8)
