Expression |
Meaning |
^abc |
Match "abc" at beginning of line |
abc$ |
Match "abc" at end of line |
^abc$ |
Match the line "abc" exactly |
^\s*abc |
Match "abc" at beginning of line, but allow leading whitespace |
^\s*end;?\s*$ |
Match a line containing only "end" or "end;" with leading or trailing whitespace |
abc|def |
Matches either "abc" or "def" |
a(b|c)d |
Matches "abd" or "acd" |
a(b|c)d\1 |
Matches "abdb" or "acdc", but it does not match "abdc" |
Control characters used in above samples
Character |
Meaning |
^ |
Beginning of line |
$ |
End of line |
\s |
Whitespace (a tab or space) |
* |
Zero or more of the preceding character |
? |
Preceding character is optional |
| |
Alternative expression |
( ) |
Subexpressions |
\1 |
Back reference to 1st subexpression |
See also