How do I output env as a runnable shell script

Question

You can trivially output your environment as a runnable shell script using

env > my_env

... later in another script ...

set -a
source my_env

This works for the most trivial cases, but fails if any special chars or spaces are in env.

How can I fix the above script so it works with stuff like a='"'"'" ?

Answer 1

The following uses bash's printf %q to escape values correctly regardless of their content. It's guaranteed to handle literally any value possible -- quotes, newlines, etc -- so long as the shell sourcing its output is bash, and so long as the operating system in use supports the /proc/self/environ facility first provided by Linux to emit the contents of the environment as a NUL-delimited stream. It uses special quoting forms such as $'\n' as and where appropriate, so its output may not be honored by pure POSIX interpreters.

#!/usr/bin/env bash
while IFS= read -r -d '' kvname; do
  k=${kvname%%=*}
  v=${kvname#*=}
  printf '%q=%q\n' "$k" "$v"
done </proc/self/environ

Note that you'll want to source the output, not run it as an external executable, if you want your current shell's environment to change. If you don't want to set -a before sourcing, add a leading export to the format string.