Cron

Tips

Run a cron job with random delay

From SO:

0 1 * * * perl -le 'sleep rand 9000' && *command goes here*

Test script as if run by cron

From SO.

Add cron entry:

 * * * * *  /usr/bin/env > /home/username/cron-env

Create a script run-as-cron:

#!/bin/sh
#
# https://stackoverflow.com/questions/8132355/test-run-cron-entry
#
# Add cron entry:
#
#   * * * * *  /usr/bin/env > /home/username/cron-env
#
# Then:
#
#   run-as-cron <cron-environment> <command>
#
# for instance
#
#   run-as-cron /home/username/cron-env 'echo $PATH'

. "$1"
exec setsid /usr/bin/env -i "$SHELL" -c "set -a; . $1; $2; echo RC is \$?" </dev/null

Note:

• setsid makes sure that script will not tied to current tty, and hence run non-interactively
• set -a makes sure that all environment variables are exported correctly.

Now to test script as if run by cron:

run-as-cron ~/cron-env 'echo $PATH'
run-as-cron ~/cron-env ~/somescript.sh