escaping double quotes and percent signs (%) in cron

Question

The following command works from prompt but not from crontab.

grep abc /var/log/messages | grep "`date '+%B %d'`" | mail -s"abc log of `hostname`" s.o+`hostname`@gmail.com

I need to add it to daily cron.

Answer 1

You have to escape the % signs. They have a special meaning in crontabs:

man (5) crontab:

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.

Answer 2

This doesn't directly answer your question, but I would suggest that you create a script file in /usr/local/bin (or ~/bin or whatever is appropriate) and call that from cron. It's easier to test and edit.