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From: byron@archone.tamu.edu (Byron Rakitzis)
Newsgroups: comp.unix.shell
Subject: Re: Remote shell question
Message-ID: <11702@helios.TAMU.EDU>
Date: 1 Feb 91 16:44:08 GMT
References: <1991Feb1.125425.14866@cbnews.att.com> <1991Feb1.145242.16915@bradley.bradley.edu>
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Organization: College of Architecture, Texas A&M University.
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In article <1991Feb1.145242.16915@bradley.bradley.edu> brad@bradley.bradley.edu (Bradley E. Smith) writes:
>In <1991Feb1.125425.14866@cbnews.att.com> smk@cbnews.cb.att.com (Stephen M. Kennedy) writes:
>
>>I want to start up a process in the background on a remote machine using
>>remsh (sysV) or rsh (bsd), e.g.,
>
>I had this same problem...what I did was to use a 'C' program below.
>
>#include	<stdio.h>
>main()
>{
>	int i;
>	for (i=0;i<20;i++) {
>		close(i);
>	}
>	i = fork();
>	if(i) 
>		exit(0);
>	execl("/usr/openwin/demo/xterm","bradley", "-ls", "-sb", "-fn","9x15", 0);
>}


You don't really need to write a C program to close file-descriptors; any reasonable
shell like sh or rc can do this for you. I have two shell scripts, "rx" and "xr".
I type:
	rx goofy
and rx does an rsh to goofy, invoking "xr" with all the necessary arguments. "xr"
then takes care to close the stupid file-descriptors (I've found that going up to 9 is
sufficient), puts xterm in the background and exits. Here are "rx" and "xr" in their
entirety:

-------------

#!/usr/arch/bin/rc
if (! ~ $#* 1) {
        echo usage: rx hostname >[1=2]
        exit 1
}

# an rx from a local window will have DISPLAY set to unix:0.0; this must be changed.
switch ($DISPLAY) {
case unix:*
	~ $#hostname 0 && hostname=`hostname
        display=`{echo $DISPLAY | sed s/unix:/$hostname:/}

case *
        display=$DISPLAY

}

rsh $1 -n bin/sh/xr $display $1 >/dev/null &

-------------

#!/usr/arch/bin/rc -l

DISPLAY=$1

xterm -ls -n $2 -title $2 </dev/null >/dev/null >[2] /dev/null <[3=] <[4=] <[5=] <[6=] <[7=] <[8=] <[9=] &
# the redirections are a hack to make sure that the rshd knows it can exit

-------------

By the way, this "rx", "xr" setup is due to Paul Haahr, who originally wrote
these scripts in sh.

Byron.
--
Byron Rakitzis
byron@archone.tamu.edu