systemtap-service(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | GLOBAL PARAMETERS | SCRIPT PARAMETERS | EXAMPLES | SEE ALSO | BUGS | COLOPHON

SYSTEMTAP(8)             System Manager's Manual            SYSTEMTAP(8)

NAME         top

       systemtap-service - SystemTap initscript and systemd service

SYNOPSIS         top

       systemtap-service COMMAND [OPTIONS] [SCRIPT...]

       service systemtap COMMAND [OPTIONS] [SCRIPT...]

DESCRIPTION         top

       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.

       The SystemTap initscript can be invoked manually using the
       systemtap-service command. On systemd-based systems, the
       initscript is controlled by systemctl with the service file
       systemtap.service.

       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.

COMMANDS         top

       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.

OPTIONS         top

       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.

GLOBAL PARAMETERS         top

       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

SCRIPT PARAMETERS         top

       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"

EXAMPLES         top

       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.conf
              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.conf
              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:

              # systemtap-service start
              # systemtap-service stop

              We could be more specific as well, for example:

              # systemtap-service start script1
              # systemtap-service 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.conf

              If the script is still running, we also need to stop it:

              # systemtap-service stop script2

              We can then also remove the cache associated with the
              script:

              # systemtap-service cleanup script2

       PREPARING FOR KERNEL UPDATES
              Usually, there is nothing to do when booting into a new
              kernel. The initscript will see that the kernel version is
              different 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:

              # systemtap-service 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:

              # systemtap-service 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 information otherwise very hard to obtain.

              We first install the script by copying it into the script
              directory 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:

              # systemtap-service 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:

              # systemtap-service onboot myscript \
              >   -o /boot/special_initramfs.img

              Once the initramfs is created, it's simply a matter of
              changing the command-line options at boot-time so that the
              new image 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:

              # systemtap-service 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:

              # systemtap-service onboot

              This will simply create a standard initramfs without any
              SystemTap 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 dracut debugging by adding 'rdinitdebug' to the
              kernel command-line and checking dmesg/journalctl -ae.
              Also, the stderr output of staprun can be captured by
              setting the LOG_BOOT_ERR option to yes.

SEE ALSO         top

       stap(1) dracut(8) new-kernel-pkg(8)

BUGS         top

       Use the Bugzilla link of the project web page or our mailing
       list.  http://sourceware.org/systemtap/ ,
       <systemtap@sourceware.org>.

COLOPHON         top

       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 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-06-18.)  If you discover 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)