#!/bin/perl

$SIG{'QUIT'} = 'quit';			# install signal handler for SIGQUIT

while ($ARGV[0] =~ /^-/) {		# parse switches
    $ARGV[0] =~ /^-h/ && ($showhost++,$silent++,shift,next);
    $ARGV[0] =~ /^-s/ && ($silent++,shift,next);
    $ARGV[0] =~ /^-d/ && ($dodist++,shift,next);
    $ARGV[0] =~ /^-n/ && ($n=' -n',shift,next);
    $ARGV[0] =~ /^-l/ && ($l=' -l ' . $ARGV[1],shift,shift,next);
    last;
}

$systype = shift;			# get name representing set of hosts

while ($ARGV[0] =~ /^-/) {		# we allow switches afterwards too
    $ARGV[0] =~ /^-h/ && ($showhost++,$silent++,shift,next);
    $ARGV[0] =~ /^-s/ && ($silent++,shift,next);
    $ARGV[0] =~ /^-d/ && ($dodist++,shift,next);
    $ARGV[0] =~ /^-n/ && ($n=' -n',shift,next);
    $ARGV[0] =~ /^-l/ && ($l=' -l ' . $ARGV[1],shift,shift,next);
    last;
}

if ($dodist) {				# distribute input over all rshes?
    `cat >/tmp/gsh$$`;			#  get input into a handy place
    $dist = " </tmp/gsh$$";		#  each rsh takes input from there
}

$cmd = join(' ',@ARGV);			# remaining args constitute the command
$cmd =~ s/'/'"'"'/g;			# quote any embedded single quotes

open(ghosts, '/etc/ghosts') || die 'No /etc/ghosts file';
					# /etc/ghosts drives the rest

$one_of_these = ":$systype:";		# prepare to expand "macros"
if ($systype =~ s/\+/[+]/g) {		# we hope to end up with list of
    $one_of_these =~ s/\+/:/g;		#  colon separated attributes
}

line: while (<ghosts>) {		# for each line of ghosts

    s/[ \t]*\n//;			# trim leading whitespace
    if (!$_ || /^#/) {			# skip blank line or comment
	next line;
    }

    if (/^([a-zA-Z_0-9]+)=(.+)/) {	# a macro line?
	$name = $1; $repl = $2;
	$repl =~ s/\+/:/g;
	$one_of_these =~ s/:$name:/:$repl:/;	# do expansion in "wanted" list
	next line;
    }

    # we have a normal line

    @attr = split;			# a list of attributes to match against
					#   which we put into an array
    $host = $attr[0];			# the first attribute is the host name
    if ($showhost) {
	$showhost = "$host:\t";
    }

    attr: while ($attr = pop(attr)) {			# iterate over gh array
	if (index($one_of_these,":$attr:") >=0) {	# is host wanted?
	    unless ($silent) { print "rsh $host$l$n '$cmd'\n"; }
	    $SIG{'INT'} = 'DEFAULT';
	    if (open(pipe,"rsh $host$l$n '$cmd'$dist |")) {	# start rsh
		$SIG{'INT'} = 'cont';
		while (<pipe>) { print $showhost,$_; }		# show results
		close(pipe);
	    } else {
		$SIG{'INT'} = 'cont';
		print "(Can't execute rsh.)\n";
	    }
	    last attr;				# don't select host twice
	}
    }
}

unlink "/tmp/gsh$$" if $dodist;

# here are a couple of subroutines that serve as signal handlers

sub cont {
    print "\rContinuing...\n";
}

sub quit {
    $| = 1;
    print "\r";
    $SIG{'INT'} = '';
    kill 2, $$;
}