bash - Accessing environment variables that don't map to valid shell variable names

Question

I'm trying to figure out how to sanely and portably (as much as possible) deal with environment variables with names that don't map to valid shell variables. It is critical that results be byte-for-byte accurate, so I'm unwilling to go through hacks such as parsing the output of the env tool.

env 'Invalid Name=Some Value' bash <<'EOF'
s='Invalid Name'
printf '%q
' "${!s}"
EOF

I would hope that the above code would emit Some Value; instead, however, it returns an empty string.

Answer 1

One unportable approach (Linux-only) is to parse /proc/self/environ:

declare -A environ
while IFS='' read -r -d ''; do
  var=${REPLY%%=*}
  val=${REPLY#*=}
  environ[$var]="$val"
done </proc/self/environ
printf '%q
' "${environ["Invalid Name"]}"