ltm rule command findstr

iRule(1)						BIG-IP TMSH Manual						  iRule(1)

findstr
       Finds a string within another string and returns the string starting at the offset specified from the match.

SYNOPSIS
       findstr STRING SEARCH_STRING (
					   SKIP_COUNT (TERMINATOR)?
				       )?

DESCRIPTION
       A custom iRule function which finds a string within another string and returns the string starting at the offset specified
       from the match.

       Syntax

       findstr   [ []]
	    * Finds the string  within  and returns a
	      sub-string based on the  and  from the
	      matched location. Note the following:
		 + If the  argument is not specified, it defaults to
		   zero. If the  argument is omitted, the
		    element must not be specified.
		 + The  argument may be either a length or string of
		   one or more characters.
		 + If the  argument is not specified, it defaults to
		   the end of the string.
		 +  and  may be delimited by whitespace only,
		   by double quotes, or by curly braces. Single quotes are taken
		   literally, rather than as delimiters, meaning that the match will fail
		   if the search string is delimited with single quotes, and the match
		   will extend to the end of the string if the termination character is
		   delimited with single quotes (neither being the intended result.)
		 + If either   contain a double quote
		   character, it can be escaped with a backslash immediately preceding the
		   character, or by enclosing the entire string in curly braces {}. Either
		   value may also be represented by a variable to take advantage of the
		   natural delimiting they offer. (Don't use curly braces to delimit
		   variables or they won't expand).
		 + This command, without  or , is
		   equivalent to the following Tcl command:
		       string range  [string first  ] end

RETURN VALUE
VALID DURING
       ANY_EVENT, GLOBAL_GTM, INFORMATIONAL_COMMAND, STRING_FUNCTION

EXAMPLES
	This iRule parses a session ID from the HTTP path and if found persists
	off of it using UIE persistence.

	when HTTP_REQUEST {

	   # Check for /install/ or /scripts/ in the path
	switch -glob [HTTP::path] {
	      "*/install/*" {

		 # Parse the URI "directory" after install. Look for /install/, skip 9 characters and match up to the next /.
		 set session_id [findstr [HTTP::path] /install/ 9 /]
	      }
	      "*/scripts/*" {
		 # Parse the URI "directory" after scripts. Look for /scripts/, skip 9 characters and match up to the next /.
		 set session_id [findstr [HTTP::path] /scripts/ 9 /]
	      }
	      default {
		 set session_id ""
	      }
	   }
	if {$session_id ne ""}{

	      # Persist on the parsed session ID for X seconds
	      persist uie $session_id 1800
	   }
	}

	This rule logs the URL value
	   (https://host.domain.com/path/file.ext?...&var=val)

	when RULE_INIT {
	  set static::payload {}
	  set static::term {">}
	  set urlresponse [findstr $static::payload URL= 4 $static::term]
	  log local0. "urlresponse $urlresponse"
	}

	Parse the domain from a SIP header. Find the first @ instance, skip 1
	character and read up until the first > or the end of the string.

	log local0. "findstr output: [findstr "" "@" 1 ">"]"
	# Logs: findstr output: sip.example.com

	Example using a multi-character terminator:

	log local0. "findstr output: [findstr "aaa123456xxyz" "aaa" 3 "xyz"]"
	# Logs: findstr output: 123456x

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-9.0.0 --First introduced the command.

BIG-IP							    2022-04-12							  iRule(1)