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Need to read a file in reverse

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# 1  
Old 03-01-2006
Need to read a file in reverse
I have to extract data from a text file which is huge in size >>10GB.
ie between two strings. If I do an ordinary sed it takes forever to come out. I was wondering if there was anyway to do the entire process in reverse and on finding the relevant string is there any way to break out of the search..
# 2  
Old 03-01-2006
reading a file in reverse,

Code:
# !/usr/bin/ksh

linecnt=`wc -l file | awk '{print $1}'`

while [ $linecnt -ge 1 ]
do
sed -n "$linecnt"p file
linecnt=$(($linecnt - 1))
done

exit 0

# 3  
Old 03-01-2006
thanks man
thanks man!!
# 4  
Old 03-01-2006
Just for info: If you have GNU coreutils installed, you'll find the tac utility (reversed cat Smilie ) does the job of reading a file from bottom to top. But this won't find your match and break out for you Smilie

Cheers
ZB
This User Gave Thanks to zazzybob For This Post:
Kibou
# 5  
Old 03-01-2006
From "HANDY ONE-LINERS FOR SED" ...
Code:
# reverse order of lines (emulates "tac")
 sed '1!G;h;$!d'               # method 1
 sed -n '1!G;h;$p'             # method 2

# 6  
Old 03-02-2006
Similiar replies to a similiar post - sort a file in reverse order. I wonder how many use the search feature of the forum.
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