On Mon, Dec 21, 2020 at 08:42:26AM -0500, Gene Heskett wrote: > I got an email from cron this morning that needs some explaining. > Here is a dcop connand _I_ can execute, no error > /opt/trinity/bin/dcop kmail KMailIface resumeBackgroundJobs > > But I put it in MY crontab and get this email > > Cron <gene@coyote> /opt/trinity/bin/dcop kmail KMailIface > resumeBackgroundJobs > From: Cron Daemon <root@coyote.coyote.den> > To: gene@coyote.coyote.den > > ERROR: Couldn't attach to DCOP server! > > I have other scripts to aid my incoming email that run as me, and use > dcop to get their job done w/o a problem. > > But put the exact same command in MY crontab and its rejected. This is, as I gather, your "personal" crontab. So the cron job is running under you UID. Good. > 2 questions, why?, and why is this email from root? As to your first question, the most probable cause is that your cron job hasn't the environment needed to get in touch with the DCOP server. One typical mechanism (note that I know zilch about DCOP, and, to be honest, would like to avoid dirtying my soul with all the saddening details ;-) is that DCOP listens on some socket. Typically (again), there is an environment variable (or several) in your session's environment containing the coordinates of said socket (or - whatever). What you can do is (besides reading DCOP's documentation, if any) issue set | grep DCOP (or some variation on it) to find about likely environment variable candidates. This, of course, from a shell running under your DE's environment (a terminal window started from your GUI will do). Then set those environment variables in your cron job. The crontab format itself (cf. man 5 crontab) has provisions to set environment -- alternatively you can call from there a script setting the necessary environment (perhaps because you don't want all your cron entries to have the same environment). Possibly DCOP has some utility to "join" a user "session", dunno. But this all is a hunch. Some tinkering needed. I test out such things by letting my cron commands append debugging stuff to some temporary file. By default, cron has no logfiles and mails you its complaints, as you already found out. As to your second question -- cron runs as root and changes to the relevant UID when needed (it couldn't were it not root).
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