perpok(8)

NAME
perpok - check a perpd(8) service

SYNOPSIS
perpok [-hV] [-b basedir ] [-u secs ] [-v] sv

DESCRIPTION
perpok is used to check that the service sv is actively running under supervision of perpd(8).

The argument sv should be a service definition directory supervised by perpd(8). perpok will look for sv in the directory given with the -b option, or as set in the PERP_BASE environmental variable, or in the current directory if neither of the previous is given.

perpok returns 0 to indicate success if the definition directory sv exists and is under the active supervision of perpd(8).

The -u option may be given to specify a minimum uptime in secs. In this case, perpok will further check that the main service itself is running, is not resetting, does not want down, and that its uptime has been at least secs seconds. If all these conditions are met, perpok returns 0 to indicate success.

If the conditions for success are not met, perpok exits non-zero.

perpok is intended primarily as a utility for boolean testing in scripting environments. See the perpstat(8) and perpls(8) utilities for more detailed status reporting.

OPTIONS

-b basedir
    Base directory. Sets the base directory containing the service definition sv. If not set, perpok will use the value set in the variable PERP_BASE, or the current directory if neither of these are defined. On a normal system, the base directory will be /etc/perp.

-h  Help. Print a brief usage message to stderr and exit.

-u secs
    Uptime. Normally perpok checks only that the sv directory is active (exists and is sticky), and that perpd(8) is actively supervising it. This option extends the checks performed by perpok to test that the main service itself is running, is not resetting, does not want down, and that its uptime has been at least secs seconds. Normally it is sensible to set secs to some small value, such as 2 or 3, which is just long enough to check that the service is not cycling on restarts.

-V  Version. Print the version number to stderr and exit.

-v  Verbose. Normally perpok exits silently, as it is designed primarily for runscripts that might use it to perform simple dependency checks prior to starting their own services. This option causes perpok to print a message reporting either success or failure to stderr on exit.

EXAMPLES
perpok may be used as a basic dependency checking utility within service runscripts:

    #!/bin/sh
    if test ${1} = "start" ; then
      if ! perpok -u3 foo ; then
        echo "dependency foo not running"
        exit 1
      fi
      # otherwise foo ok, continue to start service:
      exec /usr/bin/bar ...
    fi

This example shows a runscript for a ``bar'' service that uses perpok to require a dependency on another service named ``foo''. If foo has not been running for at least 3 seconds, the runscript exits immediately. The perpd(8) supervisor running this service will then continue to try restarting it at one second intervals, until the perpok dependency check succeeds.

Note that, when using perpok in a normal collection of services running under perpd(8), PERP_BASE will always be properly predefined in the runscript environment.

EXIT STATUS
perpok exits with the following values:

0   Success. The service sv is active and a perpd(8) supervisor has been found running for it. Additionally, if the -u option has been given, the main service itself has been found running, not resetting, not wanting down, and with an uptime of at least secs seconds.

1   Failure. The service directory sv was found not to be active, or a perpd(8) supervisor was not found running for it, or the additional constraints imposed for uptime checking with the -u option were not met.

100 Usage error. For unknown options, missing arguments, or if sv does not name a directory. Prints a brief diagnostic message to stderr on exit.

111 System error. Unexpected failures during system calls, privilege and/or resource problems, or configuration errors in the perpd(8) system. Prints a brief diagnostic message to stderr on exit.

CAVEATS
For use as a dependency tool, perpok by itself is of course limited. As illustrated in the example section above, perpok may find a dependency running okay at startup, but there is no guarantee that it will continue to run for as long as the dependent service requires it.

A collection of services running under perpd(8) tends to be reliable, so that the use of perpok for basic dependency checking at startup is normally adequate. Interrelated services may also use perpok in combination with runscript reset targets to implement a system of stricter dependency controls.

AUTHOR
Wayne Marshall, http://b0llix.net/perp/

SEE ALSO
perp_intro(8), perpboot(8), perpctl(8), perpd(8), perpetrate(5), perphup(8), perpls(8), perpstat(8), sissylog(8), tinylog(8)