pmsnap(1) — Linux manual page


PMSNAP(1)                  General Commands Manual                 PMSNAP(1)

NAME         top

       pmsnap - generate performance summary snapshot images

SYNOPSIS         top

       $PCP_BINADM_DIR/pmsnap [-NV?]  [-c configs] [-C dir] [-f format] [-n
       names] [-o dir]

DESCRIPTION         top

       pmsnap is a shell script that is normally run periodically from
       crontab(1) to generate graphic images of pmchart(1) performance
       charts.  These images can be in any of the supported pmchart formats,
       including png, bmp, and jpeg, and may be incorporated into the
       content offered by the local web server.  By default pmsnap generates
       no textual output unless some error or warning condition is

       pmsnap generates images according to its control file,
       $PCP_PMSNAPCONTROL_PATH (or dir/control if the -C option is
       specified), and uses archive logs created by pmlogger(1) or PCP
       archive folios created by pmafm(1) and pmlogger_check(1).  Before
       attempting to configure pmsnap, it is strongly recommended that
       pmlogger be configured according to the descriptions in
       pmlogger_daily(1), pmlogger_check(1) and pmlogger(1).

       Once pmlogger has been configured, it is necessary to configure
       pmsnap as follows;

       1.     Edit the control file $PCP_PMSNAPCONTROL_PATH.  The syntax of
              this file is described in the comment at the head of the file
              and an example is supplied for one and twelve hour "Summary"
              performance charts for the local host.  Suitable arguments for
              pmchart are also described in the comment.  The user should
              consult pmchart for further details.  Note that when pmsnap is
              run, it globally substitutes the string LOCALHOSTNAME with the
              name of the local host in the control file.

       2.     Test the configuration by running
              Without any arguments pmsnap will process every non-comment
              line in $PCP_PMSNAPCONTROL_PATH.  The output images will be
              placed in the files named in the first field of each line in
              the control file, with the file format appended if necessary.
              If these file names do not start with / or .  then they are
              assumed relative to dir, as specified with the -o option.  The
              default dir is the current directory.  Note that if pmlogger
              has only been recently started (within about the last 15
              minutes), snapshot images may not be produced and no error
              messages will be issued - the reason is that pmchart can not
              use very short archives and hence, neither can pmsnap.  For
              debugging purposes the -V flag should be used.

       3.     Add an appropriate entry for pmsnap in the root user's
              crontab.  An example is supplied in

       4.     Incorporate the pmsnap images into the local WWW content.
              Usually, WWW pages use images that are relative to a
              particular document root, so it is often convenient to use the
              -o command line option to specify a sub-directory of the local
              WWW content, and then create a web page in this directory that
              shows the snapshot images with text and other content
              appropriate to the local environment.

       A sample HTML page, suitable for the Summary snapshot may be found in

       Although pmsnap attempts to flush stdio(3) output buffers in the
       relevant pmlogger processes before generating snapshots images, this
       may fail for assorted reasons and no error message will be given.

       pmsnap should not be invoked immediately after pmlogger_daily has
       rolled the logs because the new archive logs will be too short to
       obtain meaningful results.  Note however that pmsnap will not report
       errors from pmchart about not being able to comply with the -A option
       on very short archives.  In these cases no error will be reported and
       no output images will be produced.

OPTIONS         top

       The available command line options are:

       -c config-pattern
            Only process lines in the control file which match the config-
            pattern regular expression in the Config column.

       -C dir
            The control file is located in the directory dir rather than in
            the default $PCP_PMSNAPCONTROL_PATH location.

       -f format
            Set output image format.  The defaults format is png.

       -n name-pattern
            Only process lines in the control file which match the name-
            pattern regular expression (see egrep(1)) in the Name column.

       -N   Enable a ``show me'' mode, where the actions are echoed, but not
            executed, in the style of ``make -n''.  Using -N in conjunction
            with -V maximizes the diagnostic capabilities for debugging.

       -o dir
            The output images having file names which do not start with / or
            .  will be placed in a directory relative to dir, otherwise the
            output directory is relative to the current directory (i.e. the
            default value for dir is ./).  Note that dir must be a writable
            directory path and may be on an NFS or CIFS file system.

       -V   Enable verbose mode.

       -?   Display usage message and exit.

       When either -n or -c are used, pmsnap will only process lines in the
       control file which match all the supplied patterns.  If no patterns
       are given, then all lines will be processed.  These arguments allow
       multiple entries for pmsnap in crontab so that different performance
       summary images can be generated at different times or with different

FILES         top

            pmsnap control file

            summary view for pmchart

            sample HTML page for summary snapshot

            PCP archive folio for the host hostname, as generated by

            example crontab entry

SEE ALSO         top

       cron(1), crontab(1), egrep(1), pmafm(1), pmchart(1), pmlc(1),
       pmlogger(1) and pmlogger_daily(1).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨⟩.
       If you have a bug report for this manual page, send it to  This page was obtained from the project's upstream
       Git repository ⟨⟩ on
       2020-08-13.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-08-11.)  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

Performance Co-Pilot                                               PMSNAP(1)