Shell Programming and Scripting

 
 #!/usr/bin/perl 
 use strict;use warnings;
  
 open (DATA, "<servers.txt") or die "no file, $!";
@srv = <DATA>;
close (DATA);
  
 $cmd = 'uptime';

 foreach $i (@srv) {
        chomp $i;
         $up = qx/rsh $i '$cmd';
         print " $i $up";
          }
 exit(0);

#!/bin/sh
PATH=/usr/bin:/bin:/usr/sbin:/sbin:/opt/local/bin; export PATH

# prevent Solaris from running out of file descriptors
ulimit -n 1024

case `uname -s` in
SunOS)
  pingopt=""
  ;;
Linux)
  pingopt="-c 1 -w"
  ;;
HP-UX)
  pingopt="-n 1 -m"
  ;;
esac

if [ "$1" = "-bg" ]; then
  bg='&'
  shift
fi
command=$*
echo command $command
toggle=1

do_rsh(){
 # echo trying rsh first
 if perl -e "alarm 5;exec @ARGV" rsh -n "$1" ":"
 then
  : using rsh first
  rsh -n "$1" "$command"
  sleep $toggle </dev/null #otherwise Solaris may run out of sockets
 else
  : echo using ssh
  ssh -xn "$1" "$command"
 fi
}

# main loop
while read i
do
  if ping $i $pingopt 2  >/dev/null
  then
    : echo machine: $i
    eval do_rsh $i $bg
    toggle=`expr 1 - $toggle`
    sleep $toggle </dev/null #otherwise Solaris may run out of sockets
  else
    : echo $i is down
  fi
done < servers.txt

# in case rsh/ssh has corrupted the terminal:
[ -t 0 ] && stty sane