Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
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  • 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

Substitution

Processing...

Code Generator

Language

Generated Code

# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression. sed -E 's/<ref\s+((?:group|follow|extends)\s*=(?:(?!name\s*=)[\s\S])*)?name\s*=\s*(?:"\s*([^"](?:(?!\s*\\/>|\s*"\s*>|\s+(?:group|follow|extends)).)*?)\s*"|'\s*([^'"](?:(?!\s*\\/>|\s*'>|\s+(?:group|follow|extends)).)*?)\s*'|([^"](?:(?!\s*\\/>|\s*>|\s+(?:group|follow|extends)).)*))(\s+(?:group|follow|extends)\s*=(?:(?!\s*\\/>|"\s*>|'\s*>)[\s\S])*)*\s*(?:(\\/)|)>/<ref $1name="$2$3$4"$5${6:+ \/:}>/gm;t' <<< "<ref name=Test1 /><ref name=Test2 /> <ref name=Bad 1 /><ref name=Bad 2 /> <ref name=\"Test 3\"/> <ref name=\"Test 4\" /> <ref name=Test5>Foo</ref> <ref name=\"Test 6\">Foo</ref> <ref name=Test7>Foo </ref> <ref name = Test8 > Foo </ref> <ref name = Test9 > Foo </ref> <ref name=\"Test 10\">Foo </ref> <ref name = \"Test 11\" > Foo </ref> <ref name = Test12 > Foo </ref> <ref name = Test13 /> <ref name = \"Test 14\" /> <ref name = Test15 /> <ref name = \"Test 16\" /> <ref name = Test17 /> <ref name = \"Test 18\" /> <ref name=\"Test/19\" /> ==A heading== <ref name = \"Test/20\" /> <ref name = \"Test 21\"/> <ref name = \"Test / 22\"/> <ref name = \"Test > 23\"/> <ref name=\"Te>st/ 23.1\"/> <ref name =\" Test 24 \"/> <ref name='Test/ 25' /> <ref name='Test/ 26'> Foo </ref> <ref name='Te>st/ 27' /> <ref name = \" Test 28 \" >Foo</ref> <ref name='Test \"29\"' /> - This one is expected to produce invalid XML \"'Test \"29\"'\"; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: \"'Test \"2 9\"'\" <ref name = \"Test 30\" > <ref name = \"Test 31\"> <ref name = \"Test 32\" /> <ref name = \"Test 33\"/> <ref name = Test34 > <ref name = Test35> <ref name = Test36 /> <ref name = Test37/> <ref name = \" Test 38 \"/> <ref name = \" Test 39 \" /> <ref name='Test 40'/> <ref name=AAA/> <ref name=\"BBB AAA BBB\" /> <ref name=\"This \"isjustnot\" valid\"/> - This one is expected to produce invalid XML \"This \"isjustnot\" valid\"; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: \"This \"is just not\" valid\". <ref name=\"This 'actually is' valid\"/> <ref name='But this \"is also\" a problem' /> (or will be after our \" substitution) <ref name=apostrophe's /> <ref name=\"more apostrophe's\" /> <ref name='this's bad, but we can fix it!' /> <ref name='this is okay'/> <ref name=\"'this is dumb'\"/> <ref name=\"this is 'less' dumb\" /> <ref name=\"what about 'this case'\"/> <ref name=\"'or this' one\" /> <ref name=\"foo\" group=\"bar\"/> <ref name=\"foo\" group=\"bar\" /> <ref group=\"bar\" name=\"foo\" /> <ref name='foo' group='bar'/> <ref name='foo' group='bar' /> <ref group='bar' name='foo' /> <ref name=foo group=bar/> <ref name=foo group=bar /> <ref group=bar name=foo/> <ref name=\"foo\" follow=\"bar\" /> <ref name='foo' follow='bar'/> <ref name=foo follow=bar/> <ref name=\"foo\" extends=\"bar\" /> <ref name='foo' extends='bar'/> <ref name=foo extends=bar/> <ref name='foo' group=\"bar\" extends=baz follow=\"quux quux\" /> <ref group=\"bar\" name='foo' extends=baz follow=\"quux quux\" /> <ref group=\"bar\" extends=baz name='foo' follow=\"quux quux\" /> <ref group=\"bar\" extends=baz follow=\"quux quux\" name='foo' /> <ref group=\"bar\" extends=baz name=foo follow=\"quux quux\" /> <ref group=\"bar\" extends=baz name=\"foo's foo\" follow=\"quux quux\" /> <ref group=\"bar's > / bar\" extends=baz name='foos > / foo' follow=\"quux quux\" /> <ref group= \"bar's > / bar\" extends= baz name= ' foos > / foo ' follow= \"quux > quux\" /> <ref name=\"foos > / foo\" group=\"bar's > / bar\" extends=baz follow=\"quux quux\"/> <ref name = ' foos > / foo ' group = \"bar's > / bar\" extends =baz follow =\" quux quux \" /> <ref name=\"foos > / foo\" group=\"bar's > / bar\" extends=baz follow='quux quux'/> "

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 SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html