how to write it in one line..

[fetaelin]

Hi I have a litle script and want to write it in one line
I dont know how to do that .. here is the script.

#!/usr/bin/perl
open(FILE1, "<marenden");
open(FILE3, ">>result");
 
while($line = <FILE1>) {
  chop($line);
  $temp=`grep $line file2.txt`;
  print FILE3 $temp;
}
 

[miller]

One Line :)

#!/usr/bin/perl
open(FILE1, "<marenden"); open(FILE3, ">>result"); while($line = <FILE1>) {chop($line); $temp=`grep $line file2.txt`; print FILE3 $temp;}
 

- Miller

[miller]

Hi Fetaelin,

As you already know, it often is possible to create one-liners for a lot of the most typical parsing needs. However, I generally avoid this as anything more than a curiousity.

In fact your currect script, if it's hoping to do what I think it is, is actually broken. I believe that the most important goal should be to make clear readable code, not ultra compact.

To that end, here is how I personally would do the project that you have listed:

#!/usr/bin/perl
 
use File::Slurp qw(read_file);
 
use strict;
 
my $file1 = 'marenden';
my $file2 = 'file2.txt';
my $outfile = 'result';
 
my %match = map {$_ => 1} grep {! /^\s*$/} read_file($file1);
 
open(IN, $file2) or die "Can't open $file2: $!";
open(OUT, ">>$outfile") or die "Can't open $outfile: $!";
 
while (<IN>) {
print OUT if $match{$_};
}
 
close(IN);
close(OUT);
 

As you can see, this is actually more lines of code because of the separation of the file name declarations. It also would be longer still if I hadn't used the File::Slurp module as a shortcut for reading in $file1. However, this code is more readable, and definitely easier to debug.

I suggest that you first aim to write a script like this before you obsess about one-liners.

- Miller

[fetaelin]

What I ment was how to write it in one line in a command prompt and not have it as an script.
ex.:
bash$: perl the scrit as one line here...

[miller]

I know. All my previous statements still apply.

- Miller

[lokeshrajoria]

hello
if you want write in one line at the command prompt so write like this

CODE
$>perl -e 'open(FILE1, "<marenden"); open(FILE3, ">>result"); while($line = <FILE1>) {chop($line); $temp=`grep $line file2.txt`; print FILE3 $temp;}'

regard'd
Lokee.......

[miller]

Here's the closest that I believe is possible:

>perl -e"use File::Slurp ':all';%m=map{$_=>1}read_file('a.txt');append_file ('c.txt',grep{$m{$_}}read_file('b.txt'))"

Note that it does require File::Slurp, which is not a core module.

- Miller