Path not found in perl

Question

I want to obtain names of owners of files, that are in specified directory (2 in the loops is just for testing, there are only 2 files in my /media anyways). So, if user's input is "/media", i get the following output:

sh: 2: /kuba: not found sh: 2: /sf_Shared: not found root:kuba

So it seems, that the script works, but displays "not found" anyways.

my $directory =<STDIN>; #"/media"; my @ls = qx(ls $directory); chomp @ls; my @fow; for(my $i = 0; $i < 2; $i++ ) { $fow[$i] = qx(stat -c '%U' $directory/$ls[$i]); #say $fow[$i]; } chomp @fow; print "$fow[0]:$ls[0]\n";

BTW, When I remove user's input and just declare $directory as "/media", it works perfectly fine.

my $directory =<STDIN>; will give you /media\n, without stripping \n your OS will not find the directory. — Polar Bear
– Polar Bear, Commented Jun 4, 2021 at 9:37
Using chomp() to remove the newline from data read from <STDIN> is, in general, a very good idea. But in this case, it's not necessary as the string (with the newline attached) is passed to qx(ls $directory). And the shell that executes the command doesn't care that there's a newline on the end. Try perl -lE '$dir = ".\n"; say qx(ls $dir)' — Dave Cross
– Dave Cross, Commented Jun 6, 2021 at 14:32

Polar Bear · Accepted Answer · 2021-06-04 09:50:54Z

Why do not use perl instructions instead of shell calls which is an expensive on resources?

use strict; use warnings; my $dir = shift || die "Provide a directory name"; my($file, $owner); while( glob("$dir/*") ) { $file = $_; $owner = getpwuid((stat($_))[4]); write; } $~ = 'STDOUT_BOTTOM'; write; exit 0; format STDOUT_TOP = +----------------------------------------------------------+-----------------+ | File | User | +----------------------------------------------------------+-----------------+ . format STDOUT = | @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< | @<<<<<<<<<<<<<< | $file, $owner . format STDOUT_BOTTOM = +----------------------------------------------------------+-----------------+ .

Reference: shift, glob, stat, getpwuid, write, format

Could you add more comments to the code? I've first started using perl yesterday
Do you really want to recommend people use formats in 2021? :-)
@Dave Cross -- did I recommended use formats? I do not recall it, I just used format to show result -- if it exists and does the job then why not to use it. You could post your answer with more modern solution if you inclined in doing so. I still find that for perl newcomers format is very easy to comprehend and does not require deep perl experience.
@DaveCross -- your comment would have more value if you suggested something as a replacement of format, just to prove your point.
@row - Modern Perl 4 edition, webpage modern perl, Raku - Perl 6, Raku

Dave Cross · Accepted Answer · 2021-06-06 09:02:02Z

I think the easiest approach is something like this:

#!/usr/bin/perl use strict; use warnings; use feature 'say'; use File::stat; # Default to the current directory if one isn't given on # the command line. # Note: "defined-or" operator so we don't fail on a # directory called "0" my $dir = shift // '.'; # Use \Q...\E around the directory name to make life easier while (my $file = glob("\Q$dir\E/*")) { say $file; # File::stat changes the behaviour of stat() and makes # it far easier to use my $uid = stat($file)->uid; my $user = getpwuid($uid); # Simple output option :-) say "$file / $user"; }

row · Accepted Answer · 2021-06-04 09:23:47Z

2

Use the chomp function to remove trailing newline (\n) from the user input.

my $directory = <STDIN>; #"/media"; chomp($directory);

edited Jun 4, 2021 at 9:23

answered Jun 4, 2021 at 9:21

row

2008 bronze badges

3 Comments

czarniecki Over a year ago

Can't modify <HANDLE> in chomp at test.pl line 9, near "<STDIN>)" Execution of test.pl aborted due to compilation errors (#1) (F) You aren't allowed to assign to the item indicated, or otherwise try to change it, such as with an auto-increment. Uncaught exception from user code: Can't modify <HANDLE> in chomp at test.pl line 9, near "<STDIN>)" Execution of test.pl aborted due to compilation errors

TLP Over a year ago

@row chomp(my $dir = <STDIN>) works though.

Dave Cross Over a year ago

@row: You're right that you usually need to chomp() input in order to remove the newline. But that's not the problem here. As the value of $directory (with its newline attached) is passed to qx(ls $directory), the extra newline is effectively ignored. Try it for yourself - perl -lE '$dir = ".\n"; say qx(ls $dir)'

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