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# 8  
Old 04-05-2012
thanks ctsgnb, for the sed, still learning to use sed. That sed code will become handy to me .
# 9  
Old 04-05-2012
Code:
 
awk '/pattern/ {print;exit}' input.txt

This User Gave Thanks to itkamaraj For This Post:
Nick1097
# 10  
Old 04-05-2012
Quote:
Originally Posted by methyl
Code:
head -1 filename | grep "string"

However, this is faster for large files:
Code:
sed -n '1,1p;1q' bigfile | grep "string"


Could be shorten:

Code:
sed 'q' bigfile | grep "string"

Code:
sed '/string/!d;q' bigfile

This User Gave Thanks to ctsgnb For This Post:
Nick1097
# 11  
Old 04-05-2012
thanks again itkamaraj and ctsgnd
# 12  
Old 04-05-2012
sed 'q' bigfile | grep "string"
Nice post. Been looking for that one for a long time.

Any way of reading just the first line of a big file quickly is really useful. This has to be the shortest code.

Not so sure about this one because it searches the entire file if the string is not found:
sed '/string/!d;q' bigfile


For a 600 Mb text file:
Code:
time sed 'q' bigfile | grep "string"

real        0.0
user        0.0
sys         0.0

time sed '/string/!d;q' bigfile

real       47.7
user       39.2
sys         8.4

Last edited by methyl; 04-05-2012 at 06:18 PM..
This User Gave Thanks to methyl For This Post:
Nick1097
# 13  
Old 04-06-2012
-- deleted --
Last edited by ctsgnb; 04-06-2012 at 05:19 AM.. Reason: Ooops ... also scan the whole file ..
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