Running a Bash script over ssh

Question

I'm trying to write a Bash script that will SSH into a machine and create a directory. The long-term goal is a bit more complicated, but for now I'm starting simple. However, as simple as it is, I can't quite seem to get it. Here's my code:

#!/bin/bash ssh -T [email protected] <<EOI  # Fix "TERM environment variable undefined" error. TERM=dumb export TERM  # Store todays date. NOW=$(date +"%F") echo $NOW  # Store backup path. BACKUP="/backup/$NOW" [ ! -d $BACKUP ] && mkdir -p ${BACKUP} echo $BACKUP  exit EOI 

It runs without any explicit errors. However, the echoed $NOW and $BACKUP variables appear empty, and the /backup directory is not created. How do I fix this?

Answer 1

The shell on the local host is doing variable substitution on $NOW and $BACKUP because the "EOI" isn't escaped. Replace

 ssh [email protected] <<EOI 

with

 ssh [email protected] <<\EOI 

Answer 2

The variables are being evaluated in the script on the local machine. You need to subsitute the dollar signs with escaped dollar signs.

#!/bin/bash ssh -T [email protected] <<EOI  # Fix "TERM environment variable undefined" error. TERM=dumb export TERM  # Store todays date. NOW=\$(date +"%F") echo \$NOW  # Store backup path. BACKUP="/backup/\$NOW" [ ! -d \$BACKUP ] && mkdir -p \${BACKUP} echo \$BACKUP  exit EOI