Linux scripting search textfile backwards

fab1234 · 07-10-2008, 07:52 AM

hey,
i have searched a lot and not found an answer to my problem:
i simply want to find the last occurrence of pattern in a textfile or diplay a textfile backwards. is there an option to cat or ed which does that?
thx for the help
fabian

acid_kewpie · 07-10-2008, 07:59 AM

if you're already using cat, try tac instead.

fab1234 · 07-10-2008, 08:32 AM

man your kidding me
....
thanks

acid_kewpie · 07-10-2008, 03:53 PM

Yeah, tac normally gets that kind of response!

jiml8 · 07-10-2008, 08:17 PM

LOL. I hadn't heard of tac either.

Pretty cool. Geek humor

fab1234 · 07-11-2008, 06:44 AM

yep thats what it is

im pretty new to linux overall so im still finding geekish jokes all the time...
linux itself is a kind of anagram of unix i guess?

fab1234 · 07-11-2008, 06:45 AM

but back to the originial question:
i used tac | grep now but istnt there a simple option to grep or sed to search backwards?

acid_kewpie · 07-11-2008, 07:27 AM

i don't believe so, it's just such an obscure thing to want to do...

acid_kewpie · 07-11-2008, 07:28 AM

"linux" is a combination of "Linus" as it the creator Linux torvalds, and "UNIX".

ghostdog74 · 07-11-2008, 07:33 AM

without using tac, you can also use tail -n num. coupled with a loop to decrement -n backwards and search for your string with grep/awk.

acid_kewpie · 07-11-2008, 07:47 AM

hmm, so tac then right?

ghostdog74 · 07-11-2008, 07:58 AM

unless on system's without tac.

jiml8 · 07-11-2008, 09:27 AM

Quote:

Originally Posted by ghostdog74

unless on system's without tac.

Well, in that case we have this

fab1234 · 07-11-2008, 09:36 AM

well i'd say searching for the last occurence of an event in a logfile isnt so unusual is it...
...or did i miss the irony in your post?

ghostdog74 · 07-11-2008, 09:43 AM

Quote:

Originally Posted by jiml8

Well, in that case we have this

and why should i do this when tools such as tail are available? also not every environment allows compiling of source code. That doesn't matter now, since OP has the tac command available.