Problem
Have you ever duplicated a cron entry, or just wanted to find duplicate lines in a file.
Solution
Here is a simple one liner, which shows all lines which occur more than once in a file or standard output.
Example
sort cronfile.223 | uniq -c | awk ' $1 != 1 '
So to check that cron directly – just do this:
crontab -l | uniq -c | awk ' $1 != 1 '
Reference
[tags]UNIX, awk, script, uniq, Unix Coding School[/tags]
