Regular Expressions 101

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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
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • 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

/
/

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 = "os\\s*= (.*)"; final String string = "--- p0f 3.08b by Michal Zalewski <lcamtuf@coredump.cx> ---\n\n" + "[+] Closed 3 file descriptors.\n" + "[+] Loaded 324 signatures from '/etc/p0f/p0f.fp'.\n" + "[+] Will read pcap data from file 'temp.pcap'.\n" + "[+] Default packet filtering configured [+VLAN].\n" + "[+] Processing capture data.\n\n" + ".-[ 10.0.7.20/44964 -> 216.58.208.37/443 (syn) ]-\n" + "|\n" + "| client = 10.0.7.20/44964\n" + "| os = Linux 3.11 and newer\n" + "| dist = 0\n" + "| params = none\n" + "| raw_sig = 4:64+0:0:1460:mss*20,7:mss,sok,ts,nop,ws:df,id+:0\n" + "|\n" + "`----\n\n" + ".-[ 10.0.7.20/44964 -> 216.58.208.37/443 (mtu) ]-\n" + "|\n" + "| client = 10.0.7.20/44964\n" + "| link = Ethernet or modem\n" + "| raw_mtu = 1500\n" + "|\n" + "`----\n"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); if (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