Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

r"
"
gsm

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "([A-Z][a-z]{2} [A-Z][a-z]{2} \\d{2} \\d{2}:\\d{2}:\\d{2} CET \\d{4})\\n(/dev.*?) ==> (.*?)\\n.*?\\n(\\d*) bytes .*? copied, (.*?) s, (.*?) (.*?s\\n)(.*?)Exit status: (\\d*)\\n"; final String string = "Thu Feb 11 15:01:37 CET 2021\n" + "/dev/mapper/vgdata-euramis_u000 ==> /ec/prod/server/euramis/u000\n" + "1+0 records in\n" + "1+0 records out\n" + "512 bytes (512 B) copied, 0.00383015 s, 134 kB/s\n" + " Command being timed: \"dd if=/dev/zero of=/ec/prod/server/euramis/u000/TstPerf/test_512_1 bs=512 count=1 oflag=dsync\"\n" + " User time (seconds): 0.00\n" + " System time (seconds): 0.00\n" + " Percent of CPU this job got: 25%\n" + " Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00\n" + " Average shared text size (kbytes): 0\n" + " Average unshared data size (kbytes): 0\n" + " Average stack size (kbytes): 0\n" + " Average total size (kbytes): 0\n" + " Maximum resident set size (kbytes): 812\n" + " Average resident set size (kbytes): 0\n" + " Major (requiring I/O) page faults: 0\n" + " Minor (reclaiming a frame) page faults: 252\n" + " Voluntary context switches: 4\n" + " Involuntary context switches: 1\n" + " Swaps: 0\n" + " File system inputs: 0\n" + " File system outputs: 8\n" + " Socket messages sent: 0\n" + " Socket messages received: 0\n" + " Signals delivered: 0\n" + " Page size (bytes): 4096\n" + " Exit status: 0\n" + "Thu Feb 11 16:02:17 CET 2021\n" + "/dev/mapper/vgdata-euramis_u000 ==> /ec/prod/server/euramis/u000\n" + "1+0 records in\n" + "1+0 records out\n" + "512 bytes (512 B) copied, 0.00275458 s, 186 kB/s\n" + " Command being timed: \"dd if=/dev/zero of=/ec/prod/server/euramis/u000/TstPerf/test_512_1 bs=512 count=1 oflag=dsync\"\n" + " User time (seconds): 0.00\n" + " System time (seconds): 0.00\n" + " Percent of CPU this job got: 33%\n" + " Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00\n" + " Average shared text size (kbytes): 0\n" + " Average unshared data size (kbytes): 0\n" + " Average stack size (kbytes): 0\n" + " Average total size (kbytes): 0\n" + " Maximum resident set size (kbytes): 816\n" + " Average resident set size (kbytes): 0\n" + " Major (requiring I/O) page faults: 0\n" + " Minor (reclaiming a frame) page faults: 253\n" + " Voluntary context switches: 4\n" + " Involuntary context switches: 1\n" + " Swaps: 0\n" + " File system inputs: 0\n" + " File system outputs: 8\n" + " Socket messages sent: 0\n" + " Socket messages received: 0\n" + " Signals delivered: 0\n" + " Page size (bytes): 4096\n" + " Exit status: 0\n" + "Thu Feb 11 17:02:26 CET 2021\n" + "/dev/mapper/vgdata-euramis_u000 ==> /ec/prod/server/euramis/u000\n" + "1+0 records in\n" + "1+0 records out\n" + "512 bytes (512 B) copied, 0.00323523 s, 158 kB/s\n" + " Command being timed: \"dd if=/dev/zero of=/ec/prod/server/euramis/u000/TstPerf/test_512_1 bs=512 count=1 oflag=dsync\"\n" + " User time (seconds): 0.00\n" + " System time (seconds): 0.00\n" + " Percent of CPU this job got: 25%\n" + " Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00\n" + " Average shared text size (kbytes): 0\n" + " Average unshared data size (kbytes): 0\n" + " Average stack size (kbytes): 0\n" + " Average total size (kbytes): 0\n" + " Maximum resident set size (kbytes): 820\n" + " Average resident set size (kbytes): 0\n" + " Major (requiring I/O) page faults: 0\n" + " Minor (reclaiming a frame) page faults: 252\n" + " Voluntary context switches: 4\n" + " Involuntary context switches: 1\n" + " Swaps: 0\n" + " File system inputs: 0\n" + " File system outputs: 8\n" + " Socket messages sent: 0\n" + " Socket messages received: 0\n" + " Signals delivered: 0\n" + " Page size (bytes): 4096\n" + " Exit status: 0\n"; final Pattern pattern = Pattern.compile(regex, Pattern.DOTALL | Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html