shellunixcron

How is % (percent sign) special in crontab?


In crontab, can you do something like this?

* * * * * echo $( date +%F) >> /path/date.txt

Solution

  • The actual problem of your crontab line is not the $() or the backquotes. The problem is the percent sign %. It has a special meaning in crontabs.

    From the manpage:

    ...
    Percent-signs (%) in the command, unless escaped with backslash (\), 
    will be changed into newline characters, and all data after the 
    first % will be sent to the command  as standard input.
    ...
    

    If you escape the percent sign with \ it should work as expected:

    * * * * * echo $(date +\%F) >> /tmp/date.txt
    

    or

    * * * * * echo `date +\%F` >> /tmp/date2.txt
    

    both work on my site.