Howto rollover a file when size exceeds using unix find

Here is a one liner to rollover a file to file.old when it exceeds the size using find command. Lets say we have a script in cron that runs and prints messages in a log file. Overtime the log file will grow and we would want to rollover the log file to log.old. Many solutions exist by finding the size and comparing it. Here is one elegant solution in one liner. Thanks to my colleague Vlad who gave the idea for using find and exec, and I added the automatic substitution or brace expansion from my knowledge-base. Happy sharing of knowledge.

find /var/log/ -name myapp.log -size +1M -exec mv {}{,.old} ;

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bash : brace expansion for automatic substitution

Bash expands a list of strings separated by commas with in braces to a list of strings separated by spaces. For example

[unixite@theunixtips:~/> echo 111-{aa,bb,cc}+{xx,yy,zz}-222
111-aa+xx-222 111-aa+yy-222 111-aa+zz-222 111-bb+xx-222 111-bb+yy-222 111-bb+zz-222 111-cc+xx-222 111-cc+yy-222 111-cc+zz-222

There should not be any space between suffix/prefix and the start/end bracket. Otherwise it is considered as a separate list. Now coming to a real world example where you can make use of this.

mv process.log{,.old} #This will move process.log to process.log.old
mv process.log.{old,oldest} #This will move process.log.old to process.log.oldest