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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
 

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LEARN ABOUT OPENSOLARIS

uptime

uptime(1)							   User Commands							 uptime(1)

NAME

       uptime - show how long the system has been up

SYNOPSIS

       uptime

DESCRIPTION

       The uptime command prints the current time, the length of time the system has been up, and the average number of jobs in the run queue over
       the last 1, 5 and 15 minutes. It is, essentially,  the first line of a w(1) command.

EXAMPLES

       Below is an example of the output uptime provides:

	 example% uptime
	 10:47am  up 27 day(s), 50 mins,  1 user,  load average: 0.18, 0.26, 0.20

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------------------------------------+
       |ATTRIBUTE TYPE		      ATTRIBUTE VALUE		   |
       |Availability		      SUNWcsu			   |
       +-----------------------------------------------------------+

SEE ALSO

       w(1), who(1), whodo(1M), attributes(5)

NOTES

       who -b gives the time the system was last booted.

SunOS 5.11							    18 Mar 1994 							 uptime(1)
All times are GMT -4. The time now is 06:02 AM.
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