Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: While loop is causing ssh command to exit from script after first iteration.
Top Forums Shell Programming and Scripting While loop is causing ssh command to exit from script after first iteration. Post 302949532 by kchinnam on Monday 13th of July 2015 12:55:57 AM
Old 07-13-2015
While loop is causing ssh command to exit from script after first iteration.
I am trying to check multiple server's "uptime" in a loop over "ssh".
When I execute multiple ssh commands with hard coded servernames script is executing fine.

But when I pass server names using while loop, script is exiting after checking first server's status, why?

Code:
# serverList
serverA
serverB
serverC

Code:
# checkServerStatus.sh
#!/bin/bash

# This block got executed fine without exiting from script.
ssh serverA uptime
ssh serverB uptime
ssh serverC uptime

# This block is exiting from script after executing ssh once with serverA.
while read server; do
        ssh $server uptime
done < serverList

Code:
> 
# output 
$> bash -xv ./test.sh
#!/bin/bash

ssh serverA uptime
+ ssh serverA uptime
 04:38am  up 39 days  0:23,  1 user,  load average: 0.00, 0.02, 0.05
ssh serverB uptime
+ ssh serverB uptime
 04:38am  up 38 days 22:40,  0 users,  load average: 0.01, 0.04, 0.05
ssh serverC uptime
+ ssh serverC uptime
 04:38am  up 39 days  5:47,  0 users,  load average: 0.00, 0.01, 0.05


while read server; do
        ssh $server uptime
done <serverList
+ read server
+ ssh serverA uptime
 04:38am  up 39 days  0:23,  1 user,  load average: 0.00, 0.02, 0.05
+ read server

If I comment "ssh $server uptime" and simply print it "echo ssh $server uptime", while loop is not exiting.

How can I fix this or work around this?
Last edited by kchinnam; 07-13-2015 at 01:57 AM.. Reason: indentation
 

10 More Discussions You Might Find Interesting

1. Solaris

SSH doesnt exit properly from command line

I ssh to another server and run a few commands - start a few processes that run on the server. I then type exit - by my command line hangs. I have heard that it is waiting until anything processes you are running complete, but these processes are going to run 24*7*365 so obviously I cant wait.... (4 Replies)
Discussion started by: frustrated1
4 Replies

2. Shell Programming and Scripting

New iteration of for-loop without incrementing?

Another question, is it possible to, in a for-loop incrementing until it reaches a certain number, to have it loop again without incrementing? Just have it drop what it is doing when it reaches this command and start again at the same number it was at? I know I could make a while loop and just... (0 Replies)
Discussion started by: jeriryan87
0 Replies

3. UNIX for Advanced & Expert Users

Multiple ssh, shutdown and exit script

PROBLEM: I need to ssh into multiple remote machines, send a shutdown command and exit. The remote servers will then run their own scripts to gracefully shutdown their applications before shutting down. ONE: This is to be achieved without using public key authentication; this is being avoided... (2 Replies)
Discussion started by: ulemsee
2 Replies

4. Shell Programming and Scripting

howto stop loop iteration

I wonder how to stop further loop iterations when conditions gets false e.g. This file.txt contains the following structure : 1 2 3 4 5 6 7 8 9 10 How to stop iteration when if statement gets false ? for n in `cat file.txt` do if (( n<=5 )) (1 Reply)
Discussion started by: presul
1 Replies

5. Shell Programming and Scripting

while loop stops after first iteration - remote ssh exit command problem?

I have written the following script to update some Debian boxes. #!/bin/bash mxg_hosts_file="/etc/mxg/ssh-hosts" while read line ; do mxg_host="$(echo ${line} | awk -F":" '{print $1}')" mxg_port="$(echo ${line} | awk -F":" '{print $2}')" echo "Connecting and Upgrading... (3 Replies)
Discussion started by: jelloir
3 Replies

6. Shell Programming and Scripting

Do something only that last iteration of loop

I have a script with logic like: my_function() { if mkdir $1 mkdir mydir_${2} else do something else fi } read in list of items while read list do my_function $list `date` done so basically it will make a directory for every name in the list and create a directory with the... (6 Replies)
Discussion started by: glev2005
6 Replies

7. Programming

String array iteration causing segfault

I am populating an array of string and print it. But it going in infinite loop and causing segfault. char Name = { "yahoo", "rediff", "facebook", NULL }; main(int argc, char* argv) { int j = 0; ... (7 Replies)
Discussion started by: rupeshkp728
7 Replies

8. Shell Programming and Scripting

Getting the iteration count in WHILE LOOP

bash in RHEL 6.4 I have a requirement in which I want to get the iteration count from a WHILE LOOP. The below mentioned simple script test.sh works fine. In the below script, the WHILE loop will iterate every 5 seconds infinitely until it greps the string BASKETBALL from /tmp/somestring.txt... (6 Replies)
Discussion started by: John K
6 Replies

9. Shell Programming and Scripting

Loop iteration with two variables

Hello, I have been stuck on this for some time and invested many hours trying to find a solution. I am trying to either loop through two variables or or two arrays and not sure how to do it. I am limited to ksh only, and don't have the ability to do a foreach, or for i AND for j etc...I... (19 Replies)
Discussion started by: Decoy Octopus88
19 Replies

10. Shell Programming and Scripting

While loop is running only for the first iteration

Hello, I've written a script to automate encoding of all the MP4 files in a directory (incl. subdirectories). But unfortunately it's running for the first MP4 file only. My machine details: root@Ubuntu16:~# uname -a Linux Ubuntu16 4.10.0-28-generic #32~16.04.2-Ubuntu SMP Thu Jul 20 10:19:48... (2 Replies)
Discussion started by: prvnrk
2 Replies

LEARN ABOUT SUSE

ssh-keysign

SSH-KEYSIGN(8)						    BSD System Manager's Manual 					    SSH-KEYSIGN(8)

NAME

     ssh-keysign -- ssh helper program for host-based authentication

SYNOPSIS

     ssh-keysign

DESCRIPTION

     ssh-keysign is used by ssh(1) to access the local host keys and generate the digital signature required during host-based authentication with
     SSH protocol version 2.

     ssh-keysign is disabled by default and can only be enabled in the global client configuration file /etc/ssh/ssh_config by setting
     EnableSSHKeysign to ``yes''.

     ssh-keysign is not intended to be invoked by the user, but from ssh(1).  See ssh(1) and sshd(8) for more information about host-based authen-
     tication.

FILES

     /etc/ssh/ssh_config
	     Controls whether ssh-keysign is enabled.

     /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key
	     These files contain the private parts of the host keys used to generate the digital signature.  They should be owned by root, read-
	     able only by root, and not accessible to others.  Since they are readable only by root, ssh-keysign must be set-uid root if host-
	     based authentication is used.

SEE ALSO

     ssh(1), ssh-keygen(1), ssh_config(5), sshd(8)

HISTORY

     ssh-keysign first appeared in OpenBSD 3.2.

AUTHORS

     Markus Friedl <markus@openbsd.org>

BSD
								   May 31, 2007 							       BSD
All times are GMT -4. The time now is 03:19 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy