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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)^(?P<io_device_name>[a-z|0-9]+)+\s+(?P<io_read_req_per_sec>\d+\.\d+)+\s+(?P<io_write_req_per_sec>\d+\.\d+)+\s+(?P<io_read_kb_per_sec>\d+\.\d+)+\s+(?P<io_write_kb_per_sec>\d+\.\d+)+\s+(?P<io_req_avg_wait_millisec>\d+\.\d+)+\s+(?P<io_req_avg_service_millisec>\d+\.\d+)+\s+(?P<io_bandwidth_utilization_percent>\d+\.\d+)`) var str = `Device rReq_PS wReq_PS rKB_PS wKB_PS avgWaitMillis avgSvcMillis bandwUtilPct loop0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 nvme0n1 0.00 15.00 0.00 60.00 0.80 0.53 0.80 Device rReq_PS wReq_PS rKB_PS wKB_PS avgWaitMillis avgSvcMillis bandwUtilPct loop0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 loop4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 nvme0n1 10.00 15.00 445.00 60.00 41.80 15.53 100.80` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", 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 Golang, please visit: https://golang.org/pkg/regexp/