Utility to start daemons, and track whether they run or not. Meant to be used by non-root users.
usage: keepup [-u socketname] [-l logfile] [-sSKrR] <program> [args] options: -l Store program and keepup output in the file (/dev/null otherwise) -u Unix socket for communication. Otherwise, guessed using <program> -s Ask for status (running/dead) -S Stop the program -r Restart the program -R Start the program only if not started -K Kill keepup for this program -f Daemon that forks
In my crontab, this line ensures the forking daemon dictd is up, and mlnet too:
* * * * * keepup -l ~/keepup.dictd-log -R -f dictd --locale ca_ES.UTF-8 -L ~/dict/dictd.log -c ~/dict/dictd.conf * * * * * keepup -l ~/mlnet.log -R mlnet
I can check the status of them running, stop them or restart them:
$ keepup -s mlnet # check status running $ keepup -S mlnet # stop it, unblocks once stopped (or 3 sec timeout) $ keepup -s mlnet dead $ keepup -r mlnet # restart it, unblocks once it runs again (or 3 sec timeout) $ keepup -s mlnet running
Only the 'init' process can trace any daemon that forks or double forks, because as the parent dies, init gets it as a child. In linux terms, init is the global child reaper. But the 'init' process is root-owned, and this means the user can touch little of it.
I achieve similar capabilities with 'keepup' using ptrace() on linux. The procees, though, gets under ptrace during all its life, and this does not allow stracing it for example.
Poettering sent a patch for linux to allow changing the child reaper, but as of linux 3.2.7, it is not upstream still.
I think systemd has per-user kind of init scripts, I don't know if only under a kernel with the patch from Poettering above.