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PMDABASH(1)									      PMDABASH(1)

NAME
       pmdabash - Bourne-Again SHell trace performance metrics domain agent

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

DESCRIPTION
       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  num-
       ber  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
       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
       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
       $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
       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 config-
       uration file, as described in pcp.conf(5).

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

Performance Co-Pilot			       PCP				      PMDABASH(1)
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