Passing entire file to a variable in a single command

[solutions]

Hi,

I was wondering if anyone knows how to pass the contents of an entire
file to a variable IN A SINGLE LINE/COMMAND? It's trivial to do with a
few lines, but I am wondering if there is a more clever way to do this.

my $file_text = some_command( filehandle ) ???

Thanks,
David

 

[A. Sinan Unur]

(e-mail address removed) wrote in

I was wondering if anyone knows how to pass the contents of an entire
file to a variable IN A SINGLE LINE/COMMAND? It's trivial to do with a
few lines, but I am wondering if there is a more clever way to do
this.

That is called slurping a file.

my $file_text = some_command( filehandle ) ???

One way of doing that is:

#!/usr/bin/perl

use strict;
use warnings;

open my $in, '<', 'ttt.pl'
or die "Cannot open ttt.pl: $!";

my $text = do { local $/; <$in> };

print $text;

__END__

For details, see perldoc perlvar, and read about $/

These days, I prefer using File::Slurp by Uri Guttman
(we miss you Uri

You can find it on CPAN.

Sinan

 

[Gunnar Hjalmarsson]

I was wondering if anyone knows how to pass the contents of an entire
file to a variable IN A SINGLE LINE/COMMAND?

my $file_text = do { undef $/; <FH> };

 

[Gunnar Hjalmarsson]

my $file_text = do { undef $/; <FH> };

---------------------------^^^^^

Oops, please disregard my reply; Sinan showed how it can be done.

 

[Gunnar Hjalmarsson]

--------------------------^^^^^

Oops, please disregard my reply; Sinan showed how it can be done.

Since the above code also 'works', I thoght I'd say *why* (I think) it's
not good.

Just saying undef $/ affects the value of $/ globally, which may cause
surprises later on in the program. The whole point with using a block is
to limit this value of the $/ variable to the block, which you do by
instead saying

my $file_text = do { local $/; <FH> };
-------------------------^^^^^

Hopefully my explanation was not as bad as the first suggestion. ;-)