You may see Regular Expressions with forward slashes around them: /flower/

• You may see Regular Expressions with forward slashes around them: /flower/

• These slashes are a form of quoting, are not part of the Regular Expression, and may be omitted in most cases (some commands may require them, though, or something similar).

• Do not confuse Regular Expressions with filespec globbing.

• Even though some of the forms appear similar, they are not the same thing at all:

/a*/ matches any number of a's (even 0)

ls a* matches all files in the PWD that begin with a single a (at least 1)

• And watch out for Extended Regular Expressions, or subsets for special purposes, PCRE, different languages, and other confusions.