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Is there a limit of characters a command in a crontab could be ?

I have a crontab with a 178 characters command and it seems to be truncated at 164 when executed. I can tell this number from the e-mail I receive and from the vi colors changing from that point.

So, is it an "official" limitation ? I can't find any documentation about this.

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Hmm, if it did have a length limit I doubt it would be as low as you're seeing. It would be worth your while working your way through serverfault.com/questions/449651/… and then if it doesn't help update your question with your actual (suitably redacted) crontab entry. –  Iain Oct 16 '13 at 8:47
You were right, length was not the problem. See my answer. Thanks for the link. –  Ponytech Oct 16 '13 at 8:51

1 Answer 1

up vote 13 down vote accepted

Wow, I found what my problem is and it had nothing to do with line length.

It turns out that my command had a % (percent sign) in it, which has a special meaning in crontab. It is used to input text to STDIN (see Why is my crontab not working, and how can I troubleshoot it?).

So I had to escape it. My command which was:

gzip -c /path/to/a/file > /backup/dir/file-$(date +%F_%T).gz


gzip -c /path/to/a/file > /backup/dir/file-`echo $(date +\%F_\%T)`.gz
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Wouldn't be ... date '+%F_%T' sufficient? –  Jiri Xichtkniha Oct 16 '13 at 9:09
I'm guessing he's doing the echo to eliminate the newline character that date puts at the end of its output –  Ed. Oct 16 '13 at 21:36
I was wondering why editing the crontab with vim and syntax highlighting made my command look a little colorful. The % caused a couple hours' consternation! –  geerlingguy Aug 14 at 3:34

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