1. Martin Scholz
  2. whenjobs

Overview

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Whenjobs is a powerful but simple cron replacement.

Two key advantages over cron are a simpler syntax for writing rules
and a powerful dependency system that lets one job depend on variables
set when other jobs run (allowing, for example, one job to run only
when another job has finished successfully).

Below is an example whenjobs script so you can get a feel for the
language.  Read the whenjobs(1) man page for full information.

  ----------------------------------------------------------------------
  (* Every 10 minutes, get the latest tagged version from the
   * git repository.  The variable 'version' will be set to something
   * like "v1.2.3", "v1.2.4", etc over time as new releases get
   * tagged.
   *)
  every 10 minutes :
  <<
    cd /my/git/repo
    tag=`git-describe --tags`
    whenjobs --set version=$tag
  >>

  (* When the 'version' variable changes (ie. a new release is
   * tagged) try to build it.  'changes' is a function that compares
   * the previous value of a variable from when this job last ran
   * with the current value of a variable, and returns true if the
   * previous and current values are different.
   *)
  when changes version :
  <<
    cd /my/git/buildrepo
    git pull
    git reset --hard $version
    ./configure
    make clean all check dist
    whenjobs --set successful_local_build=$version
  >>

  (* In parallel, build on a remote machine. *)
  when changes version :
  <<
    ssh remote ./do_build $version
    whenjobs --set successful_remote_build=$version
  >>

  (* Only when the new release has been successfully built on local
   * and remote, upload it to the website.
   *)
  when successful_local_build == version &&
       successful_remote_build == version:
  <<
    cd /my/git/buildrepo
    curl -T name-$success.tar.gz ftp://ftp.example.com/upload/
  >>
  ----------------------------------------------------------------------

To get started with whenjobs, edit your script:

  whenjobs -e

or list the current script:

  whenjobs -l

You must run 'whenjobsd' (the whenjobs daemon) as the local user.
Each user must run their own daemon.  You can query the state of the
daemon of start it using the whenjobs command line tool:

  whenjobs --daemon-start
  whenjobs --daemon-status
  whenjobs --daemon-stop

If you want the daemon to start when the machine is booted, add the
following line to /etc/rc.local (replace 'username' with your
username):

  su username -c /usr/sbin/whenjobsd

Whenjobs is an open source project distributed under the GNU General
Public License, version 2 or at your option any later version.  Read
the file 'COPYING' for the full license.

The home page is:
http://people.redhat.com/~rjones/whenjobs

Send patches or suggestions to Richard Jones <rjones@redhat.com>.