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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.