Match only first occurrence of word in a line.

Parse Apache Error Log Line (in default format). Example: [Wed Jun 01 20:05:21.194671 2016] [core:error] [pid 40699] [client ::1:64519] PHP Parse error: syntax error, unexpected '$t' (T_VARIABLE) in /Projects/trunk/code/php/test.php on line 16

It validates an email address with alias

with Leap Year support (dd/MM/yyyy)

match with or without prevailing/trailing slashes

get special tag contains html link

Remove multiple white spaces between words and replace it with the char of your choosing.

Extract parts of an URL.

RegEx for an .htaccess rewrite into a subfolder without provoking a 'too many redirects' error

^((?!proposed_).)*((project|task)_details) matches: project_details task_details...

This expression matches human genomic coordinates, similat to those being used by genome browsers (e.g. the UCSC Genome Browser). It can match: chromosome, chromosome start, chromosome start end, chromosome start end reference sequence, chromosome start end reference sequence alternative sequence. T...