Substring syntax in iRules

substr will get at part of a string, the first argument is the string to look at, the second argument specifies how many characters to skip over (0 meaning don't skip any) and the last argument is the terminator or where to stop the substring.

For an example of the parameters, say you have the following url

http://f5.com/downloads?v13

So the HTTP::uri would be "/downloads?v13"

If I put this in an iRule:

log local0. "[substr [HTTP::uri] 0 "?"] "

Will return everything up to the ? so "/downloads" would be returned.

So in /var/log/ltm you would see something similar to this:

Mar 31 09:59:34 ltm2 info tmm1[11931]: Rule /Common/test : /downloads

Hope that helps you a bit,

Dave

looking at your rule if{[string length [substr {HTTP::uri] 0 "?"]]>0} this rule is always going to be true since the first character on a HTTP::uri is always "/" therefore the string lengh will always be greater than 0 may be you want to do if{[string length [substr {HTTP::uri] 1 "?"]]>0} this will start the string length after the first character of HTTP::uri which is always "/"

set VAR1 "/downloads/hector/file1?V12" set VAR2 [substr [VAR1] 0 "?"]

set VAR3 "/downloads/hector/fil?v13?hello" set VAR4 [substr [VAR1] 0 "?"]

set VAR5 [[substr [VAR1] 5 "?"]

In this context, wouldn't

HTTP::path

Hi Charles,

as already outlined by David, a if { [string length [substr [HTTP::uri] 0 "?"]] > 0 } will make no sense at all, since the used

[substr]

[HTTP::uri]

/

[string length]

1

To check if a HTTP query string (the portion after the first

?

Example1: Using a rather simple

if { X contain Y } then { }

if { [HTTP::uri] contains "?" } then {
     A query string is present
} else {
     A query string is NOT present
}

Example2: Using F5s

[HTTP::query]

if { [HTTP::query] ne "" } then {
     A query string is present
} else {
     A query string is NOT present
}

Note: The difference of the two syntaxes is, that the first example will also identify empty query strings (e.g.

/somepath?

/somepath?param=1

Cheers, Kai