Mini Shell

#!/usr/local/cpanel/3rdparty/bin/perl

# cpanel - scripts/checkbashshell                  Copyright 2022 cPanel, L.L.C.
#                                                           All rights reserved.
# copyright@cpanel.net                                         http://cpanel.net
# This code is subject to the cPanel license. Unauthorized copying is prohibited

use strict;

my @shells = (
    '/usr/local/cpanel/bin/jailshell',
    '/usr/local/cpanel/bin/noshell',
    '/bin/bash',
    '/bin/false',
    '/bin/ftpsh',
);

my $contents = slurp_shells();

foreach my $shell (@shells) {
    if ( $contents !~ m/$shell/ ) {
        $contents .= "$shell\n";
    }
}

write_shells($contents);

exit;

sub slurp_shells {
    open( my $shells_fh, '<', '/etc/shells' ) or die "Couldn't open /etc/shells for reading: $!";
    local $/;
    my $contents = <$shells_fh>;
    $contents .= "\n" unless $contents =~ m/\n$/;
    return $contents;
}

sub write_shells {
    my ($contents) = @_;
    open( my $shells_fh, '>', '/etc/shells' ) or die "Couldn't open /etc/shells for writing: $!";
    print {$shells_fh} $contents;
    close $shells_fh or die "Couldn't write /etc/shells. Please verify its contents! $!";
}