How to store standard error in a variable

Question

Let\'s say I have a script like the following:

useless.sh

echo \"This Is Error\" 1>&2
echo \"This Is Output\" 

And I have an

Answer 1

Improving on YellowApple's answer:

This is a Bash function to capture stderr into any variable

stderr_capture_example.sh:

#!/usr/bin/env bash

# Capture stderr from a command to a variable while maintaining stdout
# @Args:
# $1: The variable name to store the stderr output
# $2: Vararg command and arguments
# @Return:
# The Command's Returnn-Code or 2 if missing arguments
function capture_stderr {
  [ $# -lt 2 ] && return 2
  local stderr="$1"
  shift
  {
    printf -v "$stderr" '%s' "$({ "$@" 1>&3; } 2>&1)"
  } 3>&1
}

# Testing with a call to erroring ls
LANG=C capture_stderr my_stderr ls "$0" ''

printf '\nmy_stderr contains:\n%s' "$my_stderr"

Testing:

bash stderr_capture_example.sh

Output:

 stderr_capture_example.sh

my_stderr contains:
ls: cannot access '': No such file or directory

This function can be used to capture the returned choice of a dialog command.