Regex to match unique substrings?

Note, you want grep -E or egrep not grep -e as that's a different option for lists of patterns.

Ls | grep -E "\.(sty|cls)$" \. Matches literally a ". " - an unescaped .

Matches any character (sty|cls) - match "sty" or "cls" - the | is an or and the brackets limit the expression. $ forces the match to be at the end of the line Note, you want grep -E or egrep, not grep -e as that's a different option for lists of patterns.

This regex: \.(sty|cls)\z will match any string ends with . Sty or . Cls EDIT: for grep \z should be replaced with $ i.e.

\.(sty|cls)$ as jelovirt suggested.

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