how to print first 5 lines of a file

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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(Ovid) Re: how to print first 5 lines of a file by Ovid (Cardinal) on Oct 31, 2001 at 23:01 UTC
The `$.` variable holds the current input line number of the last opened filehandle. `while ( $. < 5 ) { my $line = <DATA>; print "$. -> $line"; } __DATA__ one two three four five six seven` [download] Cheers, Ovid Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l]
Re: how to print first 5 lines of a file by MZSanford (Curate) on Oct 31, 2001 at 22:50 UTC
maybe the following untested solutions. Beware, numbers 2 and 3 are a bit on the silly side. : `perl -pe 'exit if ($. > 5);'` `#!/usr/bin/perl -w use strict; my $cnt = 0; while (my $line = <>) { chomp($line); $cnt++; if ($cnt > 5) { next; } else { print "$line\n"; } }` [download] `use strict; open(PRINT,"\| lp") \|\| die "Could not start lp : $!\n"; while (my $line = <>) { print PRINT $line; last if ($. > 5); } close(PRINT);` [download] i had a memory leak once, and it ruined my favorite shirt.	[reply] [d/l] [select]
Re: how to print first 5 lines of a file by broquaint (Abbot) on Oct 31, 2001 at 22:57 UTC
Perl-ish `perl -e 'print ((<>)[0..4])' filename` [download] sh-ish `head -5 filename` [download] HTH broquaint	[reply] [d/l] [select]
(tye)Re: how to print first 5 lines of a file by tye (Sage) on Oct 31, 2001 at 23:55 UTC
I certainly wouldn't recommend the first solution as, although it looks nice, it will read the entire contents of the file(s) into memory before spitting out the first 5 lines. Better to not even read the 6th line (as demonstrated in other items in this thread), much less allocate memory for it. (: - tye (but my friends call me "Tye")	[reply]
Re: how to print first 5 lines of a file by buckaduck (Chaplain) on Nov 01, 2001 at 01:04 UTC
Just a minor modification to an earlier solution would allow you to print the first five lines of multiple files: `perl -pe 'close ARGV if $. == 5' file1 file2 ...` [download] Update: The code above fails if one if the files is less than 5 lines long! This works better: `perl -pe 'close ARGV if $. == 5 or eof' file1 file2 ...` [download] buckaduck	[reply] [d/l] [select]
Re: how to print first 5 lines of a file by jmcnamara (Monsignor) on Nov 01, 2001 at 14:44 UTC
Since `-p` generates a while loop you can also do this: `perl -pe 'last if $. > 5' filename` [download] -- John.	[reply] [d/l]
Re: how to print first 5 lines of a file by Aighearach (Initiate) on Nov 01, 2001 at 00:51 UTC
To print the first 5 lines of a file: `#!/usr/bin/perl seek( DATA, 0, 0 ); $/ = undef; print <DATA>; __DATA__` [download] -- Snazzy tagline here	[reply] [d/l]
Re: how to print first 5 lines of a file by CharlesClarkson (Curate) on Nov 01, 2001 at 03:42 UTC
`for (1 .. 5) { print scalar <>; last if eof; }` [download] Or, if you're certain there are at least five lines: `print scalar <> for 1 .. 5;` Calling the diamond operator <> in scalar context will return 1 line, assuming $/ is set to "\n". (Note - 'while' calls in scalar context while 'foreach' and 'for' call in list context.) HTH, Charles K. Clarkson	[reply] [d/l] [select]
Re: how to print first 5 lines of a file by pixel (Scribe) on Nov 01, 2001 at 13:50 UTC
Why does no-one ever use the flip-flop operator for this? `while (<>) { print if 1 .. 5; }` [download] Blessed Be The Pixel	[reply] [d/l]
Re: Re: how to print first 5 lines of a file by blakem (Monsignor) on Nov 01, 2001 at 13:59 UTC
Nice, but that still loops over the entire file... I'd exit out of the loop after the fifth line like so: `while(<>) { 1 .. 5 ? print : last; }` [download] -Blake	[reply] [d/l]