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I've setup a couple of "at" jobs to execute at specific times on CentOS 5. This morning I don't see these commands in the queue ("atq"), as expected, but I also don't see were can I check whether the daemon responsible to execute them did this on time or had any issues. Unfortunately I didn't log enough info from the scripts themselves. Any ideas?

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  • To those who marked this as a duplicate - the pointed answer was about setting up logging before the command is executed. My question is about digging up logs after the fact.
    – Capt. Crunch
    Apr 10, 2019 at 3:54

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From looking at the source of the 'at' program (from the CentOS 5.3 source repository) , it looks like it is indeed logging to syslog, but only fatal errors regarding the at daemon itself are logged (for example, if you try to run 2 at daemons at the same time).

However, process executions, resulting return code and standard error/output are not logged to syslog at all. Even when turning on debug (which requires recompilation) the log messages are not very informative (for end users) and write something like :

atd[24116]: pid 24121 exited with status 0.

Which will not help you a lot in identifying which command was ran, by which user or what was its standard output/error.

atd does send an email notification to the user who requested the command, in case the command had failed, or produced anything in it's standard output/error. But for commands that succeed without any output , no mail is sent. You can change that using the -m flag.

From at(1):

-m Send mail to the user when the job has completed even if there was no output.

Borrowed from Tom Feiner's answer from almost an identical question.

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  • At typically logs to syslog on all *nix systems I've encountered. The facility may vary: there isn't a dedicated one. I've seen daemon and cron used
    – voretaq7
    Aug 18, 2011 at 3:31
  • Thanks for both of you for your answers. You confirmed what I suspected - if my commands don't have extra-logging then at's own logging isn't going to help. However - grep'ing for "atd" through the compressed "/var/log/messages*.gz" I found hints for the execution happening by form of PAM logs at the expected times. Although this isn't conclusive at least something happened when it was expected.
    – Capt. Crunch
    Aug 19, 2011 at 5:00

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