NAME | SYNOPSIS | DESCRIPTION | INSTALLATION | INSTRUMENTATION | FILES | PCP ENVIRONMENT | SEE ALSO | COLOPHON

PMDABASH(1)                General Commands Manual               PMDABASH(1)

NAME         top

       pmdabash - Bourne-Again SHell trace performance metrics domain agent

SYNOPSIS         top

       $PCP_PMDAS_DIR/bash/pmdabash [-C] [-d domain] [-l logfile] [-I
       interval] [-t timeout] [-U username] configfile

DESCRIPTION         top

       pmdabash is an experimental Performance Metrics Domain Agent (PMDA)
       which exports "xtrace" events from a traced bash(1) process.  This
       includes the command execution information that would usually be sent
       to standard error with the set -x option to the shell.

       Event metrics are exported showing each command executed, the
       function name and line number in the script, and a timestamp.
       Additionally, the process identifier for the shell and its parent
       process are exported.

       This requires bash version 4 or later.

       A brief description of the pmdabash command line options follows:

       -d   It is absolutely crucial that the performance metrics domain
            number specified here is unique and consistent.  That is, domain
            should be different for every PMDA on the one host, and the same
            domain number should be used for the same PMDA on all hosts.

       -l   Location of the log file.  By default, a log file named bash.log
            is written in the current directory of pmcd(1) when pmdabash is
            started, i.e.  $PCP_LOG_DIR/pmcd.  If the log file cannot be
            created or is not writable, output is written to the standard
            error instead.

       -s   Amount of time (in seconds) between subsequent evaluations of
            the shell trace file descriptor(s).  The default is 2 seconds.

       -m   Maximum amount of memory to be allowed for each event queue (one
            per traced process).  The default is 2 megabytes.

       -U   User account under which to run the agent.  The default is the
            unprivileged "pcp" account in current versions of PCP, but in
            older versions the superuser account ("root") was used by
            default.

INSTALLATION         top

       In order for a host to export the names, help text and values for the
       bash performance metrics, do the following as root:

            # cd $PCP_PMDAS_DIR/bash
            # ./Install

       As soon as an instrumented shell script (see INSTRUMENTATION
       selection below) is run, with tracing enabled, new metric values will
       appear - no further setup of the agent is required.

       If you want to undo the installation, do the following as root:

            # cd $PCP_PMDAS_DIR/bash
            # ./Remove

       pmdabash is launched by pmcd(1) and should never be executed
       directly.  The Install and Remove scripts notify pmcd(1) when the
       agent is installed or removed.

INSTRUMENTATION         top

       In order to allow the flow of event data between a bash(1) script and
       pmdabash, the script should take the following actions:

            #!/bin/sh
            source $PCP_DIR/etc/pcp.sh

            pcp_trace on $@       # enable tracing
            echo "awoke, $count"

            pcp_trace off         # disable tracing

       The tracing can be enabled and disabled any number of times by the
       script.  On successful installation of the agent, several metrics
       will be available:

            $ pminfo bash
            bash.xtrace.numclients
            bash.xtrace.maxmem
            bash.xtrace.queuemem
            bash.xtrace.count
            bash.xtrace.records
            bash.xtrace.parameters.pid
            bash.xtrace.parameters.parent
            bash.xtrace.parameters.lineno
            bash.xtrace.parameters.function
            bash.xtrace.parameters.command

       When an instrumented script is running, the generation of event
       records can be verified using the pmevent(1) command, as follows:

            $ pmevent -t 1 -x '' bash.xtrace.records
            host:      localhost
            samples:   all
            bash.xtrace.records["4538 ./test-trace.sh 1 2 3"]: 5 event records
              10:00:05.000 --- event record [0] flags 0x19 (point,id,parent) ---
                bash.xtrace.parameters.pid 4538
                bash.xtrace.parameters.parent 4432
                bash.xtrace.parameters.lineno 43
                bash.xtrace.parameters.command "true"
              10:00:05.000 --- event record [1] flags 0x19 (point,id,parent) ---
                bash.xtrace.parameters.pid 4538
                bash.xtrace.parameters.parent 4432
                bash.xtrace.parameters.lineno 45
                bash.xtrace.parameters.command "((  count++  ))"
              10:00:05.000 --- event record [2] flags 0x19 (point,id,parent) ---
                bash.xtrace.parameters.pid 4538
                bash.xtrace.parameters.parent 4432
                bash.xtrace.parameters.lineno 46
                bash.xtrace.parameters.command "echo 'awoke, 3'"
              10:00:05.000 --- event record [3] flags 0x19 (point,id,parent) ---
                bash.xtrace.parameters.pid 4538
                bash.xtrace.parameters.parent 4432
                bash.xtrace.parameters.lineno 47
                bash.xtrace.parameters.command "tired 2"
              10:00:05.000 --- event record [4] flags 0x19 (point,id,parent) ---
                bash.xtrace.parameters.pid 4538
                bash.xtrace.parameters.parent 4432
                bash.xtrace.parameters.lineno 38
                bash.xtrace.parameters.function "tired"
                bash.xtrace.parameters.command "sleep 2"

FILES         top

       $PCP_PMCDCONF_PATH
                 command line options used to launch pmdabash
       $PCP_PMDAS_DIR/bash/help
                 default help text file for the bash metrics
       $PCP_PMDAS_DIR/bash/Install
                 installation script for the pmdabash agent
       $PCP_PMDAS_DIR/bash/Remove
                 undo installation script for pmdabash
       $PCP_LOG_DIR/pmcd/bash.log
                 default log file for error messages and other information
                 from pmdabash

PCP ENVIRONMENT         top

       Environment variables with the prefix PCP_ are used to parameterize
       the file and directory names used by PCP.  On each installation, the
       file /etc/pcp.conf contains the local values for these variables.
       The $PCP_CONF variable may be used to specify an alternative
       configuration file, as described in pcp.conf(5).

SEE ALSO         top

       bash(1), pmevent(1) and pmcd(1).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨http://www.pcp.io/⟩.
       If you have a bug report for this manual page, send it to
       pcp@oss.sgi.com.  This page was obtained from the project's upstream
       Git repository ⟨git://git.pcp.io/pcp⟩ on 2017-04-25.  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

Performance Co-Pilot                 PCP                         PMDABASH(1)