I have a script that backs up my Nokia N9.
It sits in a loop waiting for the directory to appear sleeping 60 seconds between checks.

If I start this in a terminal it works nicely but if I suspend the machine while the sleep command is running it never returns because sleep never finishes.

Here is the script that waits for the directory to appear:

wait_for_dir.sh:

#!/bin/bash

# Just for debugging.
#set -o verbose

dir=$1
interval=$2
echo "$dir"
while [ ! -d "$dir" ]
do
NOW=$(date "+%Y-%m-%dT%T")
echo "${NOW}: Waiting for ${dir}, sleeping ${interval}"
sleep ${interval}
done

I call it like this:

./wait_for_dir.sh "/media/kj/Nokia N9" 60s

Any idea why sleep doesn't return? Any suggestions for an alternative?

I use this as a component in a larger script that waits for the N9 and uses rsync to take a backup. Once the backup is complete it waits for the N9 to disappear and reappear before taking another backup.

are you sure this assessment is correct?
i would rather assume that the script terminates when the machine is suspended.

in any case, you should add commands to terminate before & restart the script(s) after suspend.