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]
  • Character class intersection
    [\w&&[^\d]]
  • 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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"[^\\](?:(?:\\{2})*)\$(?:(?:[=|-]?([A-Z0-9_]*[A-Z_]+[A-Z0-9_]*)|(?:{[=|-]?([A-Z0-9_]*[A-Z_]+[A-Z0-9_]*)})))") test_str = ("${HAVE_ERROR}\n" "\\\\${PATH}\n" "\\\\$SHELL\n" "\\\\\\\\${PATH}\n" "${HTTP_PORT}\n" "$HTTP_PORT\n" "$PORT\n" "$1_PORT\n" "${1_PORT}\n" "$PORT_345\n" "${PORT_345}\n" "${AZK_AGENT_CONF_FILE}\n" "${HTTP_HOST_2345}\n" "${=HTTP_HOST_2345}\n" "${-HTTP_HOST_2345}\n" "$ENV.HTTP\n\n" "# ^ should match\n\n" "# v should not match\n\n" "any_text\n" "LIKE_A_ENV_NAME\n" "\\${PATH}\n" "\\$SHELL\n" "\\ \\${PATH}\n" "\\ \\$SHELL\n" "\\\\\\${PATH}\n" "\\\\\\$SHELL\n" "$1\n" "${1}\n" "$@\n" "$?\n" "${env}\n" "${env.io}\n" "${ENV\n" "${ENV_hahaha}\n" "${ENV.HTTP}\n" "$envs.HTTP_PORT\n" "${envs.HTTP_PORT}\n" "${-net.host}\n" "${-net.port.http}\n" "${=net.port.http}\n" "<%azk.default_domain%>\n" "<%=manifest.dir%>\n" "#{-system.name}\n" "#{=manifest.dir}\n" "#{azk}\n" "#{azk.io}\n" "##hello\n" "$hello\n" "%hello%\n" "<hello>") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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 Python, please visit: https://docs.python.org/3/library/re.html