|
NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | GLOBAL PARAMETERS | SCRIPT PARAMETERS | EXAMPLES | SEE ALSO | BUGS | COLOPHON |
SYSTEMTAP(8) System Manager's Manual SYSTEMTAP(8)
systemtap - SystemTap initscript service
service systemtap COMMAND [OPTIONS] [SCRIPT...]
The SystemTap initscript aims to provide a way to run scripts as a
service and easily control them individually. Scripts can be
configured to start upon manual request, or during system startup. On
dracut-based systems, it is also possible to integrate scripts in the
initramfs and have them start during early-boot.
There are various parameters and options available to modify global
behaviour, as well as script behaviour. Dependencies between scripts
can be established so that starting one starts others.
The configuration file of the initscript is located at
${prefix}/etc/systemtap/config. Acceptable parameters are detailed in
the GLOBAL PARAMETERS section.
Scripts must be placed in the ${prefix}/etc/systemtap/script.d
directory and must have a .stp extension. When referring to them on
the command-line however, there in no need to include the .stp
extension. Script names can only contain alphanumeric characters
(and '_') and must not start with a number. The scripts directory may
be changed by setting the SCRIPT_PATH parameter in the configuration
file.
One of the commands below must be specified:
start Start SCRIPTs. If no scripts are specified, start the scripts
specified by the DEFAULT_START configuration. If DEFAULT_START
is not set, start all scripts in the script directory. For
scripts already started, the command is ignored. The command
will fail if the scripts fail to start (see also the PASSALL
configuration).
If the AUTOCOMPILE configuration is on, the command will try
to compile or update the specified scripts when one of the
below conditions is true:
- The compiled cache file does not exist.
- The mtime (modified timestamp) of the original script file
is newer than the time of the compiled script cache.
- The specified stap options used to compile the script has
been changed (see also the SCRIPT PARAMETERS section).
- The result of `uname -a` has been changed.
stop Stop SCRIPTs. If no scripts are specified, stop all running
scripts. For scripts already stopped, the command is ignored.
The command will fail if the scripts fail to stop (see also
the PASSALL configuration).
restart
Stop and start SCRIPTs.
status Show the state of SCRIPTs and their dependencies.
compile
Compile SCRIPTs but do not start them. If the scripts have
already been compiled, prompt for confirmation before
overwriting cache. Compile for the current kernel, or the
kernel release specified by the -r option.
onboot Make SCRIPTs part of the initramfs so that they are started
earlier during the boot process. This command is only
available on dracut-based systems. If no scripts are
specified, create a normal initramfs devoid of any SystemTap
files.
The initramfs is created for the current kernel, or the kernel
release specified by the -r option. The path of the created
initramfs defaults to /boot/initramfs-KVER.img, where KVER is
the output of `uname -r`. The bootloader is also updated
(using new-kernel-pkg(8)) to make the kernel entry use the new
initramfs file. Use the -o option to specify a different path
(the bootloader will not be updated).
If the output file already exists, it is overwritten, unless
the -b switch is given, in which case the file is appended
.bak rather than overwritten. However, if there is already a
.bak version of the file, the backup will not be overwritten.
WARNING: do not use the -o option of stap(1) with onboot
scripts because the script is started before the root
filesystem is even mounted. Increase the buffer size if more
space is needed.
cleanup
Delete the compiled SCRIPTs from cache. If no scripts are
specified, then all compiled scripts are deleted. Only the
cache for the current kernel is deleted, or the kernel release
specified by the -r option. Prompt for confirmation before
deleting.
Many of the commands can also take options. However, since users
can't pass these options on boot, they are only meant for managing
scripts after boot and for testing. Available options are:
-c CONFIG_FILE
Specify a different configuration file in place of the default
one.
-R When using the start and stop commands, also include the
scripts' dependencies (recursively).
-r KERNEL_RELEASE
When using the compile, onboot, and cleanup commands, specify
the target kernel version rather than using the current one.
Must be in the same format as `uname -r`.
-y Answer yes for all prompts.
-o PATH.IMG
When using the onboot command, specify the output path of the
created initramfs. When specified, the bootloader
configuration is not updated.
-b When using the onboot command, backup an existing initramfs
image by adding a .bak extension rather than overwriting it.
Without this option, the initramfs is overwritten.
These parameters affect the general behaviour of the SystemTap
initscript service. They can be specified in the configuration file.
SCRIPT_PATH
Specify the absolute path of the script directory. These are
the scripts on which the initscript can operate. Scripts must
have the .stp extension. The default path is
${prefix}/etc/systemtap/script.d.
CONFIG_PATH
Specify the absolute path of the script configuration
directory. These configuration files contain options for
specific scripts. They must have the .conf extension. The
default path is ${prefix}/etc/systemtap/conf.d.
CACHE_PATH
Specify the absolute path of the cache directory. The default
path is ${prefix}/var/cache/systemtap.
TEMP_PATH
Specify the absolute path of the temporary directory in which
SystemTap makes temporary directories to compile scripts. The
default path is /tmp.
STAT_PATH
Specify the absolute path of the directory containing PID
files used to track the status of SystemTap scripts. The
default path is ${prefix}/var/run/systemtap.
LOG_FILE
Specify the absolute path of the log file. All messages are
sent to this file, including compilation and runtime errors.
The default path is ${prefix}/var/log/systemtap.log.
PASSALL
If this is set yes, initscript commands that operate on
multiple scripts will report as failed when the action could
not be performed on at least one script. If set to no, only a
warning is emitted. The default is yes.
RECURSIVE
If this is set yes, the initscript will always follow script
dependencies recursively. This means that there is no need to
specify the -R option. This flag is effective only if you
specify script(s) from the command-line. The default is no.
AUTOCOMPILE
If this is set yes, the initscript automatically tries to
compile specified scripts when needed if there is no valid
cache. Otherwise, the related command simply fails. The
default is yes.
DEFAULT_START
Specify scripts which will be started by default. If omitted
(or empty), all scripts in the script directory will be
started. The default is "".
ALLOW_CACHEONLY
If this is set yes, the initscript will also allow operating
on scripts that are located in the cache directory, but not in
the script directory. The default is no.
WARNING: the initscript may load unexpected obsolete caches
with this option. The cache directory should be checked
before enabling this option.
LOG_BOOT_ERR
Because boot-time scripts are run before the root filesystem
is mounted, staprun's stderr cannot be logged to the LOG_FILE
as usual. However, the log can instead be output to
/var/run/systemtap/$script.log by setting LOG_BOOT_ERR to yes.
If STAT_PATH is different from the default, the log files will
be moved there upon executing any of the initscript commands.
The default is no.
Here is a global configuration file example:
SCRIPT_PATH=/var/systemtap/script.d/
PASSALL=yes
RECURSIVE=no
These parameters affect the compilation or runtime behaviour of
specific SystemTap scripts. They must be placed in config files
located in the CONFIG_PATH directory.
<SCRIPT>_OPT
Specify options passed to the stap(1) command for the SCRIPT.
Here, SCRIPT is the name of the script file without the .stp
extension. Note that the -F option is always added.
The following options are ignored when compiling scripts: -p,
-m, -r, -c, -x, -e, -s, -o, -h, -V, -k.
The following options are ignored when running starting
scripts: -h, -V, -v, -t, -p, -I, -e, -R, -r, -m, -k, -g, -P,
-D, -b, -u, -q, -w, -l, -d, -L, -F, and all long options.
<SCRIPT>_REQ
Specify script dependencies (i.e. which script this script
requires). For example, if foo.stp requires (or needs to run
after) bar.stp, set
foo_REQ="bar"
Specify multiple scripts by separating their names by spaces.
Here is a script configuration file example:
script1_OPT="-o /var/log/script1.out"
script2_OPT="-o /var/log/script2.out"
script2_REQ="script1"
INSTALLING SCRIPTS
We first copy a SystemTap script (e.g. "script1.stp") into the
script directory:
# cp script1.stp /etc/systemtap/script.d/
We can then set any script options, for example:
# vi /etc/systemtap/conf.d/group1
script1_OPT="-o /var/log/group1.out"
We then install a script (e.g. "script2.stp") which needs to
run after script1. In this case, we can do the following:
# cp script2.stp /etc/systemtap/script.d/
# vi /etc/systemtap/conf.d/group1
script2_OPT="-o /var/log/group2.out"
script2_REQ="script1"
This way, if stap(1) fails to run script1, the initscript will
not even try to run script2.
TESTING
After installing scripts, we can test that they work by simply
doing:
# service systemtap start
# service systemtap stop
We could be more specific as well, for example:
# service systemtap start script1
# service systemtap stop script1
If there were no errors, we are ready to use it.
ENABLING SERVICE
After we're satisfied with the scripts and their tests, we can
enable the SystemTap initscript service:
# chkconfig systemtap on
DELETING SCRIPTS
Scripts are deleted by simply removing them from the script
directory and removing any configuration lines specific to
them:
# rm /etc/systemtap/script.d/script2.stp
# vi /etc/systemtap/conf.d/group1
If the script is still running, we also need to stop it:
# service systemtap stop script2
We can then also remove the cache associated with the script:
# service systemtap cleanup script2
PREPARING FOR KERNEL UPDATES
Usually, there is nothing to do when booting into a new ker‐
nel. The initscript will see that the kernel version is dif‐
ferent and will compile the scripts. The compilation can be
done beforehand as well to avoid having to compile during boot
by using the -r option:
# service systemtap compile myscript -r <NEW_KERNEL_VERSION>
IMPORTING COMPILED SCRIPTS
For environments which lack compilation infrastructure (e.g.
no compilers or debuginfo), such as a production system, the
scripts can be compiled on another (development) machine and
then transferred over to the production system:
# service systemtap compile myscript -r \
> <KERNEL_VERSION_OF_TARGET_MACHINE>
# tar czf stap-scripts-<kernel-version>.tar.gz \
> /var/cache/systemtap/<kernel-version> \
> /etc/systemtap/conf.d/<configfile>
And then copy this package to the target machine and extract
it.
STARTING SCRIPTS DURING EARLY-BOOT
The initscript also allows us to start scripts earlier during
the boot process by creating an initramfs containing the
script's module. The system must be dracut-based for this to
work. Starting a script at this stage gives access to informa‐
tion otherwise very hard to obtain.
We first install the script by copying it into the script di‐
rectory as usual and setting whatever options we'd like:
# cp myscript.stp /etc/systemtap/script.d
# vi /etc/systemtap/conf.d/myscript.conf
To add the script to the initramfs, we use the onboot command:
# service systemtap onboot myscript
If the script is not already compiled and cached, it will be
done at this point. A new initramfs will then be created at
the default location. We can use the -b option to ensure that
the existing initramfs is backed up. We can then restart the
system.
USING A DIFFERENT INITRAMFS
If we would prefer to only start the script for one boot and
not others, it might be easier to instead use the -o option to
specify a different initramfs output file:
# service systemtap onboot myscript \
> -o /boot/special_initramfs.img
Once the initramfs is created, it's simply a matter of chang‐
ing the command-line options at boot-time so that the new im‐
age is used rather than the usual one.
CREATING AN INITRAMFS FOR A DIFFERENT KERNEL
Just like the compile command, we can use the -r option to
specify the kernel for which we want to create the initramfs.
This is useful when we are about to upgrade and would like to
prepare in advance. For example:
# service systemtap onboot myscript \
> -r 3.12.6-200.fc19.x86_64
REMOVING SCRIPTS FROM THE INITRAMFS
Finally, to remove all script from the initramfs, we simple
run the onboot command without specifying any scripts:
# service systemtap onboot
This will simply create a standard initramfs without any Sys‐
temTap modules inserted.
TROUBLESHOOTING EARLY-BOOT ISSUES
There can be many reasons for which the module didn't insert
or did not work as expected. It may be useful to turn on dra‐
cut debugging by adding 'rdinitdebug' to the kernel command-
line and checking dmesg/journalctl -ae. Also, the stderr out‐
put of staprun can be captured by setting the LOG_BOOT_ERR op‐
tion to yes.
stap(1) dracut(8) new-kernel-pkg(8)
Use the Bugzilla link of the project web page or our mailing list.
http://sourceware.org/systemtap/ , <systemtap@sourceware.org>.
This page is part of the systemtap (a tracing and live-system
analysis tool) project. Information about the project can be found
at ⟨https://sourceware.org/systemtap/⟩. If you have a bug report for
this manual page, send it to systemtap@sourceware.org. This page was
obtained from the project's upstream Git repository
⟨git://sourceware.org/git/systemtap.git⟩ on 2017-07-05. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
SYSTEMTAP(8)
Pages that refer to this page: stap(1)