Forum Discussion
Robert_47833
Altostratus
Altostratusone question in variable
in the syntax ,we normally use :
if { $cjj == 1} {
xxxx
}
I have a question here
sometimes I forget to define this variable cjj,is there any method I can use to make it work in this way:
evulate wether there is a varable cjj,if not define one
such as :
if $cjj exist ,else set cjj x
thanks in advance
- You can use Catch. if there is a error the catch command will catch the error and allow you to work around it with out aborting the iRule
https://devcentral.f5.com/Tutorials/TechTips/tabid/63/articleType/ArticleView/articleId/137/iRules-101--07--Catch.aspx 
Robert_47833yes,catch seems a good command ,but another question raise,
if I want to check whether one variable exists catch {command},which command I should use in the curly braces?
hooleylistCirrostratus
Or you can use [info exists variable]:
if { [info exists cjj] and $cjj == 1} {
xxxx
}
http://www.tcl.tk/man/tcl8.4/TclCmd/info.htm
Aaron- Robert_47833thanks,your answer is pretty good