chronic - runs a command quietly unless it fails

       Copyright 2010 by Joey Hess <id@joeyh.name>

       Original  concept  and  "chronic"  name  by  Chuck  Houpt.   Code for verbose and stderr trigger by Tomas
       'Harvie' Mudrunka 2016.

       Licensed under the GNU GPL version 2 or higher.

moreutils                                          2024-02-25                                         CHRONIC(1)

       chronic runs a command, and arranges for its standard out and standard error to only be displayed if the
       command fails (exits nonzero or crashes).  If the command succeeds, any extraneous output will be hidden.

       A common use for chronic is for running a cron job. Rather than trying to keep the command quiet, and
       having to deal with mails containing accidental output when it succeeds, and not verbose enough output
       when it fails, you can just run it verbosely always, and use chronic to hide the successful output.

               0    1 * * * chronic backup # instead of backup >/dev/null 2>&1
               */20 * * * * chronic -ve my_script # verbose for debugging

       chronic - runs a command quietly unless it fails

       -v  Verbose output (distinguishes between STDOUT and STDERR, also reports RETVAL)

       -e  Stderr  triggering.  Triggers output when stderr output length is non-zero.  Without -e chronic needs
           non-zero return value to trigger output.

           In this mode, chronic's return value will be 2 if the command's return value is  0  but  the  command
           printed to stderr.

       chronic [-ev] COMMAND...