regex101: build, test, and debug regex
Regular expression tester with syntax highlighting, explanation, cheat sheet for PHP/PCRE, Python, GO, JavaScript, Java, C#/.NET, Rust.
Regex that accepts only numbers (0-9) and NO characters
By putting ^ at the beginning of your regex and $ at the end, you ensure that no other characters are allowed before or after your regex. For example, the regex [0-9] matches the strings "9" as …
bash - Meaning of '^ [0-9]+$'? - Unix & Linux Stack Exchange
May 22, 2018 · The regular expression ^[0-9]+$ will only match a line that is entirely composed of digits. It will not match lines that merely begin and end with digits, e.g. it will not match the …
RegExp Characters [^0-9] - W3Schools
Description The /[^0-9]/ expression matches any character that is NOT a digit between 0 and 9.
Regular expression syntax cheat sheet - JavaScript | MDN
Jan 8, 2026 · This page provides an overall cheat sheet of all the capabilities of RegExp syntax by aggregating the content of the articles in the RegExp guide. If you need more information on a …
RegExr: Learn, Build, & Test RegEx
Regular expression tester with syntax highlighting, PHP / PCRE & JS Support, contextual help, cheat sheet, reference, and searchable community patterns.
What Does ‘^ [0-9]+$’ Mean in Bash? - Its Linux FOSS
In Bash, the regular expression ‘ ^ [0-9]+$ ‘ matches a string that contains only one or more digits (0-9) and no other characters. Using this expression, users can restrict the input …
RegEX Cheat Sheet & Quick Reference
A quick reference for regular expressions (regex), including symbols, ranges, grouping, assertions and some sa
regex - Difference between [0-9]* and [0-9] - Stack Overflow
Jul 7, 2018 · Single digits match both [0-9] (any single digit) and [0-9]* (zero or more digits, except that it isn't matching all the sequences of zero digits).
0-9])+$ RegEx supports numbers and spaces, but how to …
Aug 13, 2010 · The RegEx ^ ( [0-9])+$ supports numbers and spaces. However, I want it to support empty lines too. How?