usage: ./ssh.pl or ./ssh.pl <index of host>

ssh.pl

#!/usr/bin/perl

use strict;
use warnings;
 

# Read SSH config
my $filename = '/Users/<your user>/.ssh/config';
open(my $fh, '<:encoding(UTF-8)', $filename)
  or die "Could not open file '$filename' $!";
 

# Iterate file by line, and find hosts using regular expression
my @hosts = ();
while (my $row = <$fh>) {
  chomp $row;
  my ($host) = $row =~ /^Host (.*)$/;
  if ($host) {
  	  my $arraySize = @hosts;
	  print "$arraySize: $host\n";
	  push(@hosts,$host);
  }
}

# Get integer from user: either parameter or stdin
my $userinput;
if (defined $ARGV[0]) {
	# user passed argument when running program
	$userinput = $ARGV[0];
} else {
	# prompt user for integer
	$userinput =  <STDIN>;
	chomp ($userinput);
}

# Look up host and SSH into it
my $host = $hosts[$userinput];
if ( defined $host ) {
	print "ssh: $host\n";
	system("ssh", $host);
} else {
	print "no host for $userinput\n";
}