Ubuntu Manpage: pmgetopt - Performance Co-Pilot shell script option parser

NAME

       pmgetopt - Performance Co-Pilot shell script option parser

SYNOPSIS

       $PCP_BINADM_DIR/pmgetopt [-u?]  [-c file] [-p name] [--] [parameters]

DESCRIPTION

       pmgetopt  is  used  to  perform  command line option parsing for shell scripts used in the
       Performance Co-Pilot (PCP toolkit).  It is also used to generate usage messages for  those
       scripts.

       The  parameters  given to pmgetopt take two forms: initially, options specific to pmgetopt
       itself are passed in, and terminated using the  --  mechanism.   Thereafter,  all  of  the
       parameters  passed into the shell script should be passed (usually this is simply the "$@"
       variable).

OPTIONS

The available command line options are:

-c=file, --config=file
A configuration file in the format described below is passed to pmconfig using this
option. If this option is omitted, then pmconfig will read its configuration from
the standard input stream.

-p=name, --progname=name
When parsing the calling shell scripts parameters, error and usage messages will
contain the given program name rather than referring to pmgetopt itself as the source
of the error.

-u, --usage
A usage message appropriate for the calling shell script to present as its own can be
generated using the option.

-?, --help
Display the usage message for pmgetopt itself and exit.

pmgetopt parses the given parameters, and produces output in a format suitable for
sourcing in the calling shell script. When both short and long forms of an argument are
allowed by the specification, pmgetopt will always indicate the short form for simpler
shell processing. If arguments are presented that do not match the configuration, a
request for a usage message (-?) will be generated for the calling script to respond to.
Any non-option parameters will be echoed back to the calling script preceded by the
double-hyphen delimiter. Thus a script should stop handling options when this delimiter
is detected, and begin the handling of any non-option arguments.

Unlike with the shell built-in getopt command, variables like $OPTARG are not set and the
calling script will typically employ use of the shell built-in eval, set and positional
shift commands to ensure option processing occurs correctly.

CONFIGURATION

The configuration format used by pmgetopt is intended to closely reflect the usage message
which would be generated in the presence of invalid arguments (or the -?, --help option).

There are primarily two types of configuration line - commands and options. Commands
allow metadata to be passed into the option processing process, and options are the
allowable command line options that the shell script will accept. Command lines are
preceded by the hash character, whereas option lines will always begin with a hyphen
(either single or double). Any other line in the configuration, which may include usage
headers or descriptive text, has no impact on the option parsing and will be copied
unmodified into the usage message.

The set of commands is: getopt (provide short-argument option specification manually, if
not present this will be generated from the options presented), usage (provide short one-
line summary used at the head of the usage message, which will be prefixed by the progname
before reporting), and end which informs pmgetopt to stop processing further commands and
options - any subsequent text encountered will be simply appended to the usage message.

A short-hand notation exists for each of the standard PCP options, as described in
PCPIntro(1). If any of these options (e.g --host) appears as a single word on any line,
it will be transformed into the appropriate option for the shell script, including all
metadata about that option (whether it accepts an argument, both short and long option
forms, and so on).

Use of the equals symbol ("=") indicates the presence of a required argument to any
option, for both short and long forms. Any non-standard option must be accompanied by a
non-empty description of that argument.

EXAMPLES

       As an example, the following is a valid configuration:

            # Usage: [options] node...

            Options:
                --archive
                -d, --delay            pause between updates for archive replay
                --host
                --interval
                -i=INST, --insts=INST  comma-separated metrics instance list
                -r                     output raw counters (no rate conversion)
                --width=N              set the width of each column of output
                --timezone
                --help

       This configuration will produce the following usage message, when run as shown.

            $ pmgetopt --usage --progname=clusterstat -- "$@"
            Usage: clusterstat [options] node...

            Options:
              -a FILE, --archive=FILE
                                    metrics source is a PCP archive
              -d, --delay           pause between updates for archive replay
              -h HOST, --host=HOST  metrics source is PMCD on host
              -t DELTA, --interval=DELTA
                                    sampling interval
              -i INST, --insts=INST comma-separated metrics instance list
              -r                    output raw counters (no rate conversion)
              --width=N             set the width of each column of output
              -Z TZ, --timezone=TZ  set reporting timezone
              -?, --help            show this usage message and exit

       Several  examples  of  pmgetopt use form part of the PCP toolkit, in particular the pcp(1)
       and pmlogmv(1) scripts provide good reference examples.

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
       configuration file, as described in pcp.conf(5).