Having an issue passing variables to subshell

Question

So here is my problem, I have this script I wrote where I'm exporting two variables however they're not making it into the subshell.

The point of this script is to change a users password and clear out their pam_tally for CentOS and Ubuntu hosts.

A little background is that this environment's users are managed by puppet but the passwords are all local, ssh keys are not allowed either (this is set in stone and can't be changed so I have to work with what I got) and the reason is that every log in has to be manual (even number of sessions are limited to two so you can't even user csshX effectively).

Here is my script

 #!/bin/bash echo "Please enter user whose password you want to change" read NEWUSER echo "Please enter new password for user" read -s -p "Temp Password:" TEMPPASSWORD PASSWORD=$TEMPPASSWORD export PASSWORD NEWUSER2=$NEWUSER export NEWUSER2 for i in HOST{cluster1,cluster2,cluster3}0{1..9} do ping -c 2 $i && (echo $i ; ssh -t $i ' sudo pam_tally2 --user=$NEWUSER2 --reset echo -e "$PASSWORD\n$PASSWORD" | sudo passwd $NEWUSER2 sudo chage -d 0 $NEWUSER2 ') done

Alfe · Accepted Answer · 2015-08-14 22:23:51Z

You are using ssh to connect to a remote host and run a script on that host. ssh does not export the local environment to the remote session but instead performs a login on the remote host which sets the environment according to the remote user's configuration on the remote host.

I suggest you pass all needed values via the command you want to execute. This could be done like this:

ssh -t $i ' sudo pam_tally2 --user='"$NEWUSER2"' --reset echo -e "'"$PASSWORD"'\n'"$PASSWORD"'" | sudo passwd '"$NEWUSER2"' sudo chage -d 0 '"$NEWUSER2"

Watch closely how this uses quotes. At each occasion where you used a variable, I terminate the single-quoted string (using '), then add a double-quoted use of the variable (e. g. "$PASSWORD") and then start the single-quoted string again (using ' again). This way, the shell executing the ssh command will expand the variables already, so you have no need to pass them into the remote shell.

But be aware that special characters in the password (like " or ' or or maybe a bunch of other characters) can mean trouble using this simple mechanism. To be safe against this as well, you would need to use the %q format specifier of the printf command to quote your values before passing them:

ssh -t "$i" "$(printf ' sudo pam_tally2 --user=%q --reset { echo %q; echo %q; } | sudo passwd %q sudo chage -d 0 %q' \ "$NEWUSER2" "$PASSWORD" "$PASSWORD" "$NEWUSER2" "$NEWUSER2")"

You could also go through a script. cat scriptfile.sh | ssh $i 'touch scriptfile.sh && chmod 755 scriptfile.sh && cat > scriptfile.sh && ./scriptfile.sh' ; /bin/rm -f scriptfile.sh - which requires a temporary scriptfile, or you could prepare a variable which you echo "$VAR" | ssh ... into a remote scriptfile.

Collectives™ on Stack Overflow

Having an issue passing variables to subshell

1 Answer 1

2 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Linked

Related