Question

I’m starting with bash at university, anyone has any idea how to solve that problem:

Show first 5 files for each directory from $PATH variable, if some directory doesn’t exist, don’t show error message.

Solution can be something like:

ls -a ``echo $PATH | sed "s/:/ /g"`` 2> /dev/null

it works, maybe there exists other option but I don’t know how to limit results by 5 per each show block?

Answer 1

Try the following code :

printf '%s\n' ${PATH//:/ } |
    while read dir; do
        /bin/ls 2>/dev/null -1 "$dir" |
            head -5
    done

• the ${PATH//:/* /} part use bash parameter expansion
• printf '%s\n' is printing any words separated by spaces on newlines
• /bin/ls -1 list files on newlines. I puts the full PATH to override the alias
• head -5 print the first 5 lines

edit

This is another solution using perl with a formatted output :

#!/usr/bin/perl -lw

use strict;
use Env qw/PATH/;

my $hash = {};
my @paths = split ":", $PATH;

push @{ $hash->{"$_"} }, glob "${_}/*" for @paths;

foreach my $key (keys(%$hash)) {
    next unless $hash->{$key}->[0];
    print "$key";
    for (my $i = 0; $i < 5; $i++) {
        my $line = $hash->{$key}->[$i];
        print "  $line" if $line;
    }
    print "\n";
}

Output example :

/opt/kde/bin
  /opt/kde/bin/checkXML
  /opt/kde/bin/cupsdconf
  /opt/kde/bin/cupsdoprint
  /opt/kde/bin/dcop
  /opt/kde/bin/dcopclient


/usr/bin
  /usr/bin/2to3
  /usr/bin/2to3-2.7
  /usr/bin/2to3-3.2
  /usr/bin/7z
  /usr/bin/7za