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
Processing...

Test String

Code Generator

Generated Code

// include the latest version of the regex crate in your Cargo.toml extern crate regex; use regex::Regex; fn main() { let regex = Regex::new(r"(?sm)^\s+(?:re)?start.*?(haproxy_check).*?;;").unwrap(); let string = "case \"$1\" in start) echo -n \"Starting haproxy \" ## Start daemon with startproc(8). If this fails ## the return value is set appropriately by startproc. haproxy_check /sbin/startproc $HAPROXY_BIN -D -f $HAPROXY_CONF -p $HAPROXY_PID # Remember status and be verbose rc_status -v ;; stop) echo -n \"Shutting down haproxy \" ## Stop daemon with killproc(8) and if this fails ## killproc sets the return value according to LSB. /sbin/killproc -TERM $HAPROXY_BIN # this is additional forcing kill command to ensure that all processes are stopped. /usr/bin/killall -9 $HAPROXY_BIN || true # Remember status and be verbose rc_status -v ;; try-restart|condrestart) ## Do a restart only if the service was active before. ## Note: try-restart is now part of LSB (as of 1.9). ## RH has a similar command named condrestart. if test \"$1\" = \"condrestart\"; then echo \"${attn} Use try-restart ${done}(LSB)${attn} rather than condrestart ${warn}(RH)${norm}\" fi $0 status if test $? = 0; then # we us reload here for a graceful restart during update $0 reload else rc_reset # Not running is not a failure. fi # Remember status and be quiet rc_status ;; restart) ## Stop the service and regardless of whether it was ## running or not, start it again. $0 stop $0 start haproxy_check # Remember status and be quiet rc_status ;; check) ## Stop the service and regardless of whether it was ## running or not, start it again. echo -n \"Checking config of haproxy \" haproxy_check rc_status -v ;; reload|force-reload) ## Like force-reload, but if daemon does not support ## signaling, do nothing (!) haproxy_check # If it supports signaling: echo -n \"Reload service haproxy \" $HAPROXY_BIN -p $HAPROXY_PID -D -f $HAPROXY_CONF -sf $(cat $HAPROXY_PID) rc_status -v ;; status) echo -n \"Checking for service haproxy \" ## Check status with checkproc(8), if process is running ## checkproc will return with exit status 0. # Return value is slightly different for the status command: # 0 - service up and running # 1 - service dead, but /var/run/ pid file exists # 2 - service dead, but /var/lock/ lock file exists # 3 - service not running (unused) # 4 - service status unknown :-( # 5--199 reserved (5--99 LSB, 100--149 distro, 150--199 appl.) # NOTE: checkproc returns LSB compliant status values. /sbin/checkproc $HAPROXY_BIN # NOTE: rc_status knows that we called this init script with # \"status\" option and adapts its messages accordingly. rc_status -v ;; probe) ## Optional: Probe for the necessity of a reload, print out the ## argument to this init script which is required for a reload. ## Note: probe is not (yet) part of LSB (as of 1.9) test $HAPROXY_CONF -nt $HAPROXY_PID && echo reload ;; *) echo \"Usage: $0 {start|stop|status|try-restart|restart|force-reload|reload|probe}\" exit 1 ;; esac"; // result will be an iterator over tuples containing the start and end indices for each match in the string let result = regex.captures_iter(string); for mat in result { println!("{:?}", mat); } }

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 Rust, please visit: https://docs.rs/regex/latest/regex/