Ubuntu – Export $DISPLAY value in Shell script

You could use printf -v to create variables dynamically, for example:

temp=somename
echo $temp
printf -v $temp "Test value"
echo $somename

This will output "Test value".

Note that temp="$(date +%s)" won't work, because the output of $(date +%s) is numeric, and variable names in Bash cannot start with a number. You would have to give it a non-numeric prefix, for example:

temp="t$(date +%s)"

To export the variable, you can simply do:

export $temp

Here's a complete example, with proof that the variable really gets exported in the environment:

temp=t$(date +%s)
echo $temp
printf -v $temp "Test value"
export $temp
sh -c "echo \$$temp"

Outputs for example:

t1486060416
Test value

Within sh which is actually dash on Ubuntu the builtin command return can returns only numerical values - exit statuses, which have a meaning in a context of a function or sourced script. Source man sh:

The syntax of the return command is

return [exitstatus]

Everything other with your shell script looks correct. I think you need to use echo $COLOR instead return and suppress other echo-es.

In case you need to return more data to the main script you can output everything as one line and divide the separate fields by some character that will play role of a delimiter in the main script on which base you can convert the string into an array. For example (where , is our delimiter and -n will suppers the newline character within echo):

echo -n "$COLOR","$exitstatus"

The other information that is provided by the script and is not required by the main script could be redirected to some log file:

$ cat whiptail.sh

#!/bin/sh
log_file='/tmp/my.log'

COLOR=$(whiptail --inputbox "What is your favorite Color?" 8 78 Blue --title "Example Dialog" 3>&1 1>&2 2>&3)
exitstatus=$?

if [ $exitstatus = 0 ]; then
    echo "User selected Ok and entered $COLOR" > "$log_file"
    echo -n "$COLOR","$exitstatus"
else
    echo "User selected Cancel."  >> "$log_file"
    echo -n "CANCEL","$exitstatus"
fi

Unfortunately I don't have much experience with Python, but here is a sample .py script that can handle the output of the above .sh script (reference):

$ cat main-script.py

#!/usr/bin/python
import subprocess

p = subprocess.Popen(['./whiptail.sh'], stdout=subprocess.PIPE)
p = p.communicate()[0]
p = p.split(",")
print "Color:    " + p[0]
print "ExitCode: " + p[1]