Re: proper escaping sequence in crontab?

[Theo de Raadt <deraadt@cvs.openbsd.org>]

> I want my daily/weekly cron files to spool to disk as email is disabled.
> So I tried the following command but it's getting chopped off right
> after the + (plus) sign. Why is this happening and how can I fix it? If
> I put any character between the + and % it works but that character
> shows up in the filename which is not what I want.
> 
> /bin/sh /etc/daily 2>&1 > /root/daily.`date "+%y%m%d"`
> 
> which cron says becomes the following when executed:
> ( /bin/sh /etc/daily 2>&1 > /root/daily.`date "+)

It appears you did not read the crontab(5) manpage:

       The  ``sixth''  field (the rest of the line) specifies the
       command to be run.  The  entire  command  portion  of  the
       line,  up to a newline or % character, will be executed by
       /bin/sh or by the shell specified in the SHELL variable of
       the  cronfile.   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.

That said, there is a bug which prevents \% from being properly
un-escaped later on when the command is executed.  I have just fixed
this bug in cron, and things now work better.