retrieving a line from the middle of a huge file
- From: joshkorn@xxxxxxxxx
- Date: 12 Oct 2006 15:20:57 -0700
For simplicity, let's imagine I have a file with 1000 lines (of varying
lengths). Let's say I want the 500th line. On unix command line, I
do:
head -500 filename | tail -1
and it runs quickly, no problem.
In perl, I do:
for(my $i=0; $i<499; $i++){
<FILE>;
}
my $line = <FILE>;
and it runs comparitively slowly.
Is there some way to have it do it as fast as the system?
Much thanks.
p.s. Actual specs: 100 files at a time, 100M lines each, and I need to
paste together the second column of specified lines into a single file
of matrix format. The specified lines come in chunks: e.g. lines
10,000,000 to 10,099,999, then lines 11,000,000 to lines 11,099,999.
.
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