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grep string from a file

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# 1  
Old 08-31-2010
grep string from a file
hi everyone,

1.txt
Code:
12
34
56

2.txt
Code:
456----aa
abc;b;b;b
34;a;a;a;a

output is
Code:
456----aa
34;a;a;a;a

my code is: tmp.txt
Code:
#!/usr/bin/perl
use strict;
use warnings;

my $tmp;
open(FH,'1.txt') or die "$!";
while(<FH>){
        chomp;
        $tmp = `grep "$_" 2.txt`;
        if ($tmp ne '') {
                print "$tmp";
        }
}
close FH;

it works, but the problem you image 1.txt has 30k lines, 2.txt has many many k lines, this script is very low using `grep`.
Please advice, any simple way. Thanks
# 2  
Old 08-31-2010
Try:
Code:
grep -f 1.txt 2.txt

This User Gave Thanks to zaxxon For This Post:
jimmy_y
# 3  
Old 08-31-2010
Quote:
Originally Posted by zaxxon
Try:
Code:
grep -f 1.txt 2.txt

ha~~~ Smilie so simple!!!
Thanks

---------- Post updated at 03:24 AM ---------- Previous update was at 03:15 AM ----------

err...
the line of code is simple, but actually when i run my two big files, it takes the same amout of time compare with the original script, and it takes more memory. Smilie
# 4  
Old 08-31-2010
You can try if fgrep will be faster.
This User Gave Thanks to zaxxon For This Post:
jimmy_y
# 5  
Old 08-31-2010
Quote:
Originally Posted by zaxxon
You can try if fgrep will be faster.
Smilie:
the script by using grep need more than 5 mins, but fgrep takes just 1 second Smilie: still cannot believe fgrep is so fast than grep.
# 6  
Old 08-31-2010
Just for the record, I think you two mean grep -f, not fgrep ..
# 7  
Old 08-31-2010
Quote:
Originally Posted by Scrutinizer
Just for the record, I think you two mean grep -f, not fgrep ..
assume 1.txt has 33k lines, 2.txt has 20k lines (each line has many many fields)
if "grep -f 1.txt 2.txt", it took me 5 mins to get the result, but if "fgrep -f 1.txt 2.txt", it took just a second to get the same result.
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