Shell Programming and Scripting

#!/bin/perl -w #-d

use strict;

sub remsh_test()
{
my $host = $_[0];

printf "\n----\n\n";

printf "remsh to $host with system call\n";
my $result = system ("remsh $host hostname");
printf "Contents of \$result :\n";
printf "$result\n";

printf "\n----\n\n";

printf "remsh to $host with backticks\n";
$result = `remsh $host hostname`;
printf "Contents of \$result :\n";
printf "$result\n";

printf "\n----\n\n";

printf "remsh to $host with open\n";
open (RESULT, '-|', "remsh $host hostname");
while (<RESULT>) {
        chomp;
        printf "Contents of \$_ :\n";
        printf "$_\n";
        $result = $_;
        printf "Contents of \$result :\n";
        printf "$result\n";
}
close (RESULT);

printf "\n----\n\n";

} # end sub

# === MAIN ===

foreach my $host ("nbsol151", "nbfuz159") {
        &remsh_test($host);
}

----

remsh to nbsol151 with system call
nbsol151
Contents of $result :
0

----

remsh to nbsol151 with backticks
Contents of $result :
nbsol151


----

remsh to nbsol151 with open
Contents of $_ :
nbsol151
Contents of $result :
nbsol151

----


----

remsh to nbfuz159 with system call
rcmd: nbfuz159: Unknown host
Contents of $result :
256

----

remsh to nbfuz159 with backticks
rcmd: nbfuz159: Unknown host
Contents of $result :


----

remsh to nbfuz159 with open
rcmd: nbfuz159: Unknown host

$somevar = system( "[some command ] 2&>1");

----

remsh to nbsol151 with system call
Contents of $result :
0

----

remsh to nbsol151 with backticks
Contents of $result :


----

remsh to nbsol151 with open

----


----

remsh to nbfuz159 with system call
rcmd: nbfuz159: Unknown host
Contents of $result :
0

----

remsh to nbfuz159 with backticks
rcmd: nbfuz159: Unknown host
Contents of $result :


----

remsh to nbfuz159 with open
rcmd: nbfuz159: Unknown host

----

printf "remsh to $host with backticks\n";
$result = `remsh $host hostname 2> /dev/null`;
chomp $result;
printf "Contents of \$result :\n";
printf "$result\n";
if ($result eq $host) {
        printf "remsh successful.\n";
} else {
        printf "remsh NOT successful.\n";
}

----

remsh to nbsol151 with backticks
Contents of $result :
nbsol151
remsh successful.

----

remsh to nbfuz159 with backticks
Contents of $result :

remsh NOT successful.

my $host = "nbsol152";
my $redirect = "2>&1";
my $return;
$return = `remsh $host hostname $redirect`;
printf "return : $return\n";