Cron passes a minimal set of environment variables to your jobs. To see the difference, add a dummy job like this:
* * * * * env > /tmp/env.output
/tmp/env.output to be created, then remove the job again. Now compare the contents of
/tmp/env.output with the output of
env run in your regular terminal.
A common "gotcha" here is the
PATH environment variable being different. Maybe your cron script uses the command
somecommand found in
/opt/someApp/bin, which you've added to
/etc/environment? cron ignores
PATH from that file, so runnning
somecommand from your script will fail when run with cron, but work when run in a terminal. It's worth noting that variables from
/etc/environment will be passed on to cron jobs, just not the variables cron specifically sets itself, such as
To get around that, just set your own
PATH variable at the top of the script. E.g.
# rest of script follows
Some prefer to just use absolute paths to all the commands instead. I recommend against that. Consider what happens if you want to run your script on a different system, and on that system, the command is in
/opt/someAppv2.2/bin instead. You'd have to go through the whole script replacing
/opt/someAppv2.2/bin instead of just doing a small edit on the first line of the script.
You can also set the PATH variable in the crontab file, which will apply to all cron jobs. E.g.
15 1 * * * backupscript --incremental /home /root