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

use strict; my $str = 'SLF4J: Class path contains multiple SLF4J bindings. SLF4J: Found binding in [jar:file:/opt/spark/jars/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: Found binding in [jar:file:/opt/spark/jars/slf4j-log4j12-1.7.30.jar!/org/slf4j/impl/StaticLoggerBinder.class] SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation. SLF4J: Actual binding is of type {"log_timestamp": "2021-02-18T11:33:23.114+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "QuorumPeer[myid=2](plain=/0.0.0.0:2181)(secure=disabled)", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "PeerState set to LOOKING"} {"log_timestamp": "2021-02-18T11:33:23.115+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "WorkerSender[myid=2]", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "Failed to resolve address: zk-2.zk-headless.intam.svc.cluster.local"} java.net.UnknownHostException: zk-2.zk-headless.intam.svc.cluster.local at java.net.InetAddress.getAllByName0(InetAddress.java:1281) at java.net.InetAddress.getAllByName(InetAddress.java:1193) at java.net.InetAddress.getAllByName(InetAddress.java:1127) at java.net.InetAddress.getByName(InetAddress.java:1077) at org.apache.zookeeper.server.quorum.QuorumPeer$QuorumServer.recreateSocketAddresses(QuorumPeer.java:194) at org.apache.zookeeper.server.quorum.QuorumPeer.recreateSocketAddresses(QuorumPeer.java:764) at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:699) at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:618) at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:477) at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:456) at java.lang.Thread.run(Thread.java:748) {"log_timestamp": "2021-02-18T11:33:23.115+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "WorkerSender[myid=2]", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "Failed to resolve address: zk-2.zk-headless.sxc.svc.cluster.local"} java.lang.InterruptedException: Timeout while waiting for epoch from quorum at org.apache.zookeeper.server.quorum.Leader.getEpochToPropose(Leader.java:1227) at org.apache.zookeeper.server.quorum.Leader.lead(Leader.java:482) at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:1284) ... 19 more {"log_timestamp": "2021-02-18T11:33:23.114+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "QuorumPeer[myid=2](plain=/0.0.0.0:2181)(secure=disabled)", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "PeerState set to LOOKING"} {"log_timestamp": "2021-02-18T11:33:23.115+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "WorkerSender[myid=2]", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "Failed to resolve address: zk-2.zk-headless.intam.svc.cluster.local"} java.net.UnknownHostException: zk-2.zk-headless.intam.svc.cluster.local at java.net.InetAddress.getAllByName0(InetAddress.java:1281) at java.net.InetAddress.getAllByName(InetAddress.java:1193) at java.net.InetAddress.getAllByName(InetAddress.java:1127) at java.net.InetAddress.getByName(InetAddress.java:1077) at org.apache.zookeeper.server.quorum.QuorumPeer$QuorumServer.recreateSocketAddresses(QuorumPeer.java:194) at org.apache.zookeeper.server.quorum.QuorumPeer.recreateSocketAddresses(QuorumPeer.java:764) at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:699) at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:618) at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:477) at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:456) at java.lang.Thread.run(Thread.java:748) {"log_timestamp": "2021-02-18T11:33:23.115+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "WorkerSender[myid=2]", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "Failed to resolve address: zk-2.zk-headless.sxc.svc.cluster.local"} org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:699) dorg.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManorg.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:699)'; my $regex = qr/^(?:SLF4J:|\w+(?:\.\w+)+).*(?:\R(?!(?:SLF4J:|\w+(?:\.\w+)+)|{).*)*/mp; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

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 Perl, please visit: http://perldoc.perl.org/perlre.html