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

`
`
gm

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 = "(?m)^NAME=\"(?P<name>(?P<disk>[a-z]+)(?P<partition>\\d*))\"\\sFSTYPE=\"(?P<fstype>\\w*)\"\\sMOUNTPOINT=\"(?P<mountpoint>[\\w\\[\\]/]*)\"\\sSIZE=\"(?P<size>\\d*)\"\\sTYPE=\"(?P<type>\\w+)\"$"; final String string = "NAME=\"loop0\" FSTYPE=\"LVM2_member\" MOUNTPOINT=\"\" SIZE=\"20971520000\" TYPE=\"loop\"\n" + "NAME=\"sda\" FSTYPE=\"\" MOUNTPOINT=\"\" SIZE=\"171798691840\" TYPE=\"disk\"\n" + "NAME=\"sda1\" FSTYPE=\"ext4\" MOUNTPOINT=\"/boot\" SIZE=\"1073741824\" TYPE=\"part\"\n" + "NAME=\"sda2\" FSTYPE=\"LVM2_member\" MOUNTPOINT=\"\" SIZE=\"170723901440\" TYPE=\"part\"\n" + "NAME=\"sdb\" FSTYPE=\"\" MOUNTPOINT=\"\" SIZE=\"32212254720\" TYPE=\"disk\"\n" + "NAME=\"sdb1\" FSTYPE=\"LVM2_member\" MOUNTPOINT=\"\" SIZE=\"32211206144\" TYPE=\"part\"\n" + "NAME=\"sdc\" FSTYPE=\"\" MOUNTPOINT=\"\" SIZE=\"53687091200\" TYPE=\"disk\"\n" + "NAME=\"sdc1\" FSTYPE=\"LVM2_member\" MOUNTPOINT=\"\" SIZE=\"53686042624\" TYPE=\"part\"\n" + "NAME=\"sr0\" FSTYPE=\"\" MOUNTPOINT=\"\" SIZE=\"1073741312\" TYPE=\"rom\"\n" + "NAME=\"cl_ctos8auto-root\" FSTYPE=\"xfs\" MOUNTPOINT=\"/\" SIZE=\"106300440576\" TYPE=\"lvm\"\n" + "NAME=\"cl_ctos8auto-root\" FSTYPE=\"xfs\" MOUNTPOINT=\"/\" SIZE=\"106300440576\" TYPE=\"lvm\"\n" + "NAME=\"cl_ctos8auto-swap\" FSTYPE=\"swap\" MOUNTPOINT=\"[SWAP]\" SIZE=\"8497659904\" TYPE=\"lvm\"\n" + "NAME=\"cl_ctos8auto-home\" FSTYPE=\"xfs\" MOUNTPOINT=\"/home\" SIZE=\"108536004608\" TYPE=\"lvm\"\n" + "NAME=\"cl_ctos8auto-var_log\" FSTYPE=\"ext4\" MOUNTPOINT=\"/opt/imsdb/chroot-sybase/var/log\" SIZE=\"32208060416\" TYPE=\"lvm\"\n" + "NAME=\"b38ad718--fc07--11ea--9894--0050569ae644-fea1a18c--fc07--11ea--9894--0050569ae644\" FSTYPE=\"ext4\" MOUNTPOINT=\"/opt/intelerad/atlas/1/storage/b30f29df-8fc2-4db5-8c17-4275cdae6b3f\" SIZE=\"20967325696\" TYPE=\"lvm\""; final Pattern pattern = Pattern.compile(regex, 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