[brad0]

Don't listen to the guys who are saying not to learn bash. In the right circumstance bash is much better than any verbose python script.

I'd say learn the following topics:

pipe grep sed awk find

Once you feel comfortable using and combining these tools you should be able to find out the rest by yourself.

[fenwick67]

At the risk of being pedantic, grep sed awk and find are not bash, they are their own programs. You can run find from any shell, or without a shell at all.

[TheGrassyKnoll]

I prefer Perl over Awk.