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

NAME

       pmgetopt - Performance Co-Pilot shell script option parser

SYNOPSIS

       $PCP_BINADM_DIR/pmgetopt   [-c|--config   file]  [-p|--progname  name]  [-u|--usage]  [--]
       [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).

The options specific to pmgetopt are as follows:

-c,--config
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,--progname
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.

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 log 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