Find and replace.

Regular expressions are useful for extracting information from any text by searching one or more matches of a specific pattern.

A regex usually comes within this form /abc/ where the search pattern is delimited by two slash characters /.


^The matches any string that starts with The
end$ matches a string that ends with end
^The end$ exact string match (starts and ends with The end)
long matches any string that has the text long in it


abc* matches a string that has ab followed by zero or more c
abc+ matches a string that has ab followed by one or more c
abc? matches a string that has ab followed by zero or one c

Character classes

User uppercase to negate.

\d* matches a single character that is a digit
\w* matches a word character (alphanumeric character plus underscore)
\s* matches a whitespace character (includes tabs and line breaks)
.* matches any character


In order to be taken literally, you must escape the characters ^.[$()|*+?{\ with a backslash \ as they have special meaning.


g global does not return after the first match, restarting the subsequent searches from the end of the previous match
m multi-line when enabled ^ and $ will match the start and end of a line, instead of the whole string
i insensitive makes the whole expression case-insensitive (for instance /aBc/i would match AbC)