Shell Programming and Scripting

Background info :
Linux machines, /bin/bash shell .

I have several remote machines. I want to create a variable for each of these remote machines, by retrieving some data remotely for each of them. As this may take some time for each remote machine, I want to launch these commands woth a for command and to set in background each loop.

Like this :

Code:

for machine in server1 server2
> do
> eval ${machine}_nr=`ssh -q $machine "hostname"`
> done &
[1] 31891

After a second (the ssh commands are already finished) I press an enter and I get this in my prompt (some info regarding my background commands.

Code:

$:
[1]+  Done                    for machine in server1 server2;
do
    eval ${machine}_nr=`ssh -q $machine "hostname"`;
done
$:
$: echo $server1_nr

$:

As you can see the background commands weren't executed, therefore I have no value in the variables server1_nr and server2_nr. The whole chain of commands works fine, otherwise, if I don't send it in background :

Code:

$: for machine in server1 server2
> do
> eval ${machine}_nr=`ssh -q $machine "hostname"`
> done
$:
$: echo $server1_nr
server1.ced.h3g.it

What am I doing wrong ?

---------- Post updated at 08:08 AM ---------- Previous update was at 06:52 AM ----------

A short update :
I think the problem is not so much related with the fact that I'm using a looping statement but with the fact that I cannot create a variable in background (the process of creating the variable itself to be set in background) :

Code:

$: var=78 &
[1] 17155
$:
[1]+  Done                    var=78
$:
$: echo $var

$:

I think it is because if i sent the command "var=78" in background, a separate shell is created, therefore, the variable var will exist only in that shell.
How can I overcame that ?

If var is less than 128 you can use exit status of each child run eg:

Code:

function child_a {
   sleep 5
   return 21
}
 
function child_b {
   sleep 2
   return 17
}
child_a &
r[1]=$!
 
child_b &
r[2]=$!
 
for pid in ${r[@]}
do
   printf "Exist status of $pid is "
   wait $pid
   echo $?
done

Try this test, Put you statements in a script and submit it like below:

Code:

#!/usr/bin/ksh
# Script:  test.sh
for machine in server1 server2
do
  eval ${machine}_nr=`ssh -q $machine "hostname"`
done

nohup test.sh &