regular expression on a range of number...

[Louis]

hi all,

i am setting up swatch (syslog monitoring) for email alert. i have a
cisco 2924 switch and i wanna to ignore alarm from fastethernet0/0-22,
but keep alarm on 0/23-24. i think the following statement works, but
can i shorten the statement?

/FastEthernet0\/[0-9],/ || /FastEthernet0\/1[0-9],/ ||
/FastEthernet0\/2[01],/

thanks

 

[Gunnar Hjalmarsson]

i am setting up swatch (syslog monitoring) for email alert. i have a
cisco 2924 switch and i wanna to ignore alarm from fastethernet0/0-22,
but keep alarm on 0/23-24. i think the following statement works, but
can i shorten the statement?

/FastEthernet0\/[0-9],/ || /FastEthernet0\/1[0-9],/ ||
/FastEthernet0\/2[01],/

/FastEthernet0\/(?:1?[0-9]|2[0-2]),/

 

[Louis]

/FastEthernet0\/(?:1?[0-9]|2[0-2]),/

Thanks a ton...

I think I understand the last part '|2[0-2]'. Can you explain
'?:1?[0-9]'? Or ':' -? '|'?

Thanks

 

[Gunnar Hjalmarsson]

/FastEthernet0\/(?:1?[0-9]|2[0-2]),/

Thanks a ton...

I think I understand the last part '|2[0-2]'. Can you explain
'?:1?[0-9]'? Or ':' -? '|'?

(?: ) is to be seen together, and is for non-capturing grouping.

But, honestly, there is absolutely no reason why I would try to
explain regex syntax, since it's explained in the docs much better
than I ever would be able to do. See for instance:

http://www.perldoc.com/perl5.8.4/pod/perlretut.html

P.S. You can shorten it with another three characters:

/FastEthernet0\/(?:1?\d|2[0-2]),/