First, that's an interesting use of push - you could just do @DATA=<ORIGFILE>;, but I don't think that's a big deal.

Second, you'll find that you'll want to open your file for writing by using the open, FILEHANDLE, ">filename" nomenclature.

Third, as written, your code will open a file called "host1 BUNCHOFDATAINALINE". You might want to split( /pattern/, expression ) each line of the file so you can separately refer to the separate pieces of data, like ( $HOSTNAME, $SOMEDATA ).

$/  =  q#(\w)#  ;  sub  sig { print scalar reverse  join  ' ',  @_  } 
+ sig
map { s$\$/\$/$\$2\$1$g && $_ } split( ' ', ",erckha rlPe erthnoa stJu
+" );
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ok, on the split function, can i split $line into two sections, one being the first 16 characters, then name the file via this string of characters?

If you're specifically interested in just the first 16 characters, you could also look into substr( EXPR, OFFSET, LENGTH). When I saw "host1 BUNCHOFDATAONALINE" I assumed that splitting on whitespace was what you were looking for, but when you phrase it as "one being the first 16 characters", substr comes to mind.

You may wish to examine the differences between split and substr to see which would suit you better.



--chargrill

---

$/  =  q#(\w)#  ;  sub  sig { print scalar reverse  join  ' ',  @_  } 
+ sig
map { s$\$/\$/$\$2\$1$g && $_ } split( ' ', ",erckha rlPe erthnoa stJu
+" );
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ok, on the split function, can i split $line into two sections, one being the first 16 characters, then name the file via this string of characters?

Yes, you can, but then chances are that substr or unpack are better suited for the tast. Split works best for splitting on a pattern. Well, more precisely it is exactly for splitting on a pattern!

Doing a file open and file close for every line can get really expensive and time consuming if there happen to be thousands of lines of input.

Perl allows you to store file handles in a hash, so you can open a new file each time you see a new "hostname" string, and just re-use that handle whenever you see the same name again:

# set $listfile to some constant, or to $ARGV[0] (and supply the file 
+name
# as a command-line arg when you run the script)

my %outfh;  # hash to hold output file handles

open ORIGFILE, $listfile or die "$listfile: $!";
while ( <ORIGFILE> ) {
    my ( $host, $data ) = split " ", $_, 2;
    if ( ! exists( $outfh{$host} )) {
        open( $outfh{$host}, ">", $host ) or die "$host: $!";
    }
    print $outfh{$host} $data;
}
# perl will flush and close output files when done
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I am trying out your code; I replaced the $listfile with $ARGV[0].

#!/usr/bin/perl


# set $listfile to some constant, or to $ARGV[0] (and supply the file
#+name
# as a command-line arg when you run the script)

my %outfh;  # hash to hold output file handles

open ORIGFILE, $ARGV[0] or die "$ARGV[0]: $!";
while ( <ORIGFILE> ) {
    my ( $host, $data ) = split " ", $_, 2;
    if ( ! exists( $outfh{$host} )) {
        open( $outfh{$host}, ">", $host ) or die "$host: $!";
    }
    print $outfh{$host} $data;
}
# perl will flush and close output files when done
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But this produces a syntax error of

Scalar found where operator expected at ./nocsplit.pl line 17, near "}
+ $data"
        (Missing operator before  $data?)
syntax error at ./nocsplit.pl line 17, near "} $data"
Execution of ./nocsplit.pl aborted due to compilation errors.
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It seems to not like the

print to $outfh{$host} $data;
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There may be a more elegant solution, but graff's code works if you change the line:

print $outfh{$host} $data;

to:

my $fh = $outfh{$host};
print $fh $data;
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dave

print $outfh{$host} $data;
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In addition to Not_a_Number's solution by means of assigning to a temporary variable, another possible one is that given in perldoc -f print:

print { $outfh{$host} } $data;
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People generally do

use strict;
use warnings;
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nowadays, and that's the single best piece of advice I can give you!

Also, people do

my @DATA=<ORIGFILE>;
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but then they also prefer to avoid slurping in files all at once, and they iterate on the lines instead with a while loop rather than with a for one:

while (my $line=<ORIGFILE>) { # ...
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In any case you have to specify '>' mode in open for writing (and '>>' for appending). More generally I recommend you to stick with the three args form of open and lexical handles, and always check the return value:

open my $in, '<', "whatever" or die "can't open `whatever': $!\n";
open my $out, '>', "whatever" or die "can't open `whatever': $!\n";
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