topic Re: remsh break the while loop in Operating System - HP-UX

remsh break the while loop

jose-kl — Sun, 20 May 2007 09:42:56 GMT

I working with posix shell and trying to run remsh
command in a while loop but the while loop break after
the first iteration of the loop .

Any idea why it happen ?

System is HPUX11.11

For example :

Assume I have 3 lines in /tmp/test

# cat /tmp/test
line1
line2
line3

#cat /tmp/test | while read line
>do
>remsh hostname1 date
>done
Thu May 17 14:03:43 IST 2007

if the other hand if I'm running the date command on local machine (not via remsh )
it runs the loop 3 times as expected .

# cat /tmp/test | while read line
> do
> date
> done
Sun May 20 23:25:54 METDST 2007
Sun May 20 23:25:54 METDST 2007
Sun May 20 23:25:54 METDST 2007

Thanks for any reply

Jose

Re: remsh break the while loop

James R. Ferguson — Sun, 20 May 2007 12:23:22 GMT

Hi Jose:

You need to add the '-n' switch:

while read line
do
remsh hostname1 -n date
done < /tmp/test

Notice that I eliminated the extra 'cat' process and performed the read directly.

The 'remsh' manpages note that, "By default, remsh reads its standard input and sends it to the remote command because remsh has no way to determine whether the remote command requires input. The -n option redirects standard input to remsh from /dev/null."

Hence the behavior you see.

Regards!

...JRF...

Re: remsh break the while loop

Dennis Handly — Sun, 20 May 2007 16:55:00 GMT

Your example doesn't show any use of $line, was that while-loop really needed? (Perhaps the name of each host?)

Note if the size of the file "test" is small, you can also use a for-loop:
for line in $(< /tmp/test ); do
remsh hostname1 -n date
done

Re: remsh break the while loop

jose-kl — Mon, 21 May 2007 01:20:59 GMT

Hello James,

Great.

I add the "-n" and it work fine .

Thanks,
Jose