scripting - return value of remote commands?
 

Hi,

I'm a bash script newbie . . . I am trying to capture the result of a command executed remotely. I realise this will not work but I'll post what I have just so you know where I'm at!

MOUNTED=`ssh $HOST_IP "mount|grep /dev/sdb1"`;

What I want to capture in the variable MOUNTED is the return value of "mount|grep /dev/sdb1" which is executed on the remote machine at $HOST_IP, but I have no idea how to proceed from the above which obviously doesn't work . . .

Any help or pointers would be great!

Thanks

S

By 'return value" do you mean the command's exit code?

Try this:

This will work because "echo $?" prints the exit code of the most recently executed command. But remember that "0" represents success and a nonzero code represents an error.

But maybe you should actually say what you want. It's not clear from your message.

Thanks for your reply

Ok, what I want to do is check to see if /dev/sdb1 is mounted on the remote machine. If I have

MOUNT=mount|grep -q /dev/sdb1

I can check to see if MOUNT is empty - if so the drive is not mounted. I wanted to repeat the procedure on a remote machine. I guess your solution doesn't work because the exit status is zero for all calls to mount, even though it IS what I asked for!!

Again any help would be appreciated - perhaps I'm barking up the wrong tree!

Cheers

S

Hi

ssh also passes the return codes from the remote computer to the host. So you can use $? like usual.

ssh $HOST_IP "mount |grep /dev/sda1" &>/dev/null
echo $?
0
ssh $HOST_IP "mount |grep /dev/sdz1" &>/dev/null
echo $?
1

That's it - Thanks!