Remote ssh command not sending echo variable from a ksh script on AIX

Question

I'm need to get the value of a variable from a remote host in a script using SSH and have to source an environment file first that does a shift at the end of its run.

The command works locally and I can see what it's doing with an echo. I've spent a good day researching this and testing every combination of single and double quotes I could find. I hope someone has a quick solution.

The first SSH command returns "YES" which is what I expect. How do I get the second variable to the remote host without it being expanded?

Here's the script:

#!/bin/ksh
set -x
SIDHost=p16
ThisSID=test
ssh -q $SIDHost ". /tmp/useq $ThisSID; echo \$HOST_IS_ERPDB"
ERPTest=`ssh -q ${SIDHost} ". /usr/vmmc/bin/oracle_scripts/useq $ThisSID; echo \$HOST_IS_ERPDB"`

Script run:

+ SIDHost=p16
+ ThisSID=test
+ ssh -q p16 . /usr/vmmc/bin/oracle_scripts/useq test; echo $HOST_IS_ERPDB
YES
+ + ssh -q p16 . /usr/vmmc/bin/oracle_scripts/useq test; echo NO
ERPTest=NO

Answer 1

Inside the backticks, a backslash quotes the next character. So you're getting the output from the command

ssh -q ${SIDHost} ". /usr/vmmc/bin/oracle_scripts/useq $ThisSID; echo $HOST_IS_ERPDB"

You need \\ instead:

ERPTest=`ssh -q ${SIDHost} ". /usr/vmmc/bin/oracle_scripts/useq $ThisSID; echo \\$HOST_IS_ERPDB"`

so that ERPTest is set to the output of the command

ssh -q ${SIDHost} ". /usr/vmmc/bin/oracle_scripts/useq $ThisSID; echo \$HOST_IS_ERPDB"

Alternatively, use $(…) instead of the obsolescent `…`. Note that on some versions of AIX you may need to use /bin/sh or ksh93 instead of the antique /bin/ksh.

ERPTest=$(ssh -q ${SIDHost} ". /usr/vmmc/bin/oracle_scripts/useq $ThisSID; echo \$HOST_IS_ERPDB")