Concise way to get only global and local shell variables (not functions or env. variables) in Bash

Question

How would I go about getting the values of local and global variables in Bash, skipping any functions and environment variables?

declare -p gives me the whole bunch. But it's not clear whether I can rely on the output format of declare -p. From the help declare output it is also not obvious whether whether declare -p may include functions or not. Experimentation suggests it doesn't.

Example: there are variables whose output will be similar to:

declare -- VARNAME="Variable value"

... and others where the options to declare are given instead of --, e.g.:

declare -ir UID="197609"

Now, if I knew that I can rely on this format for the output of declare, I could simply use a while loop similar to this one to limit the output to read-only integer variables:

while read -r decl opts keyval; do
    if [[ "$opts" == *ir* ]]; then # could obviously also be case/esac
        echo "$keyval"
    fi
done < <(declare -p)

... and thereby weed out the types of variables I am not interested in.

Question: But can I rely on this to be the case? If not, what other concise method exists to filter the variables by some given criteria?

NB: I am interested in Bash >=5.0 and I am currently using 5.2.15 on my machine.

Answer 1

You can query the type of variables using typeset / declare -p. +F excludes functions, and variables set through the environment are marked -x, so we can regex the hell out of this:

declare -p +F | grep -Ev '^declare -x'

should you just need the names:

declare -p +F | sed -n  's/^declare -[^x] \([^=]*\).*/\1/p'

Answer 2

In bash:

comm -23 -- <(compgen -v | sort) <(compgen -e | sort)

Where comm subtracts the exported variables from the list of all variables.

With zsh:

set -o extendedglob
print -roC1 -- ${(k)parameters[(R)^*export*]}

$parameters is a special associative array that maps parameter names to their list of type and attributes.

Here, we print, raw, ordered on 1 Column the keys of that associative array for which the value does not contain export.

You might want to also exclude the special, hide, or undefined (ready to be autoloaded) ones.