Tools to be comfortable with

• Command line
• grep (show lines containing pattern in a file list).  Useful grep flags:
• -i: ignore case
• -w: word
• -v: all but pattern
• Basic shell pipelines, e.g. grep bear | grep -i polar
• Recursive grep is very useful, e.g.:
  
• find . -type f -print0 | xargs -0 grep !* /dev/null
• Failing that, grep pattern * */* */*/* etc. ...
• lxr can substitute for recursive grep (sample)
  
• tar, configure, make, make install