Matching Regular Expressions

• grep is a filter, and can easily be used with stdin:

echo <a string> | grep [options] <reg exp>

• Some useful options (there are more) include:

• -c count occurrences only
• -E extended patterns (egrep)
• -i ignore case distinctions
• -n include line numbers
• -q quiet; no output to stdout or stderr
• -r recursive; search all subfolders
• -v select only lines not matching
• -w match "words" only (be careful: what constitutes a word?)