Get rights for specific user on file/dir

Question

I'm searching for a command that essentially would do the following: check which rights a user has on a file/dir (including ACL) and return it.

E.g. say you have the following directory:

-rw-r--r-- 1 user1 group1 [snip] file1
-rw-rw-r-- 1 user2 group1 [snip] file2
drwxrwx--- 1 user2 group2 [snip] dir1

Then the commands & output should be (if user1 is a member of only group1):

rights user1 file1 => r-- or 4
rights user1 file2 => rw- or 6
rights user1 dir1 => --- or 0

Is there such a command available or which tools/commands can't be used to construct a script which would do it?

Answer 1

I elaborate the following bash code

#!/bin/bash
# Use: $0 user files

user="$1"
shift
sudo -u "$user" bash -c 'for f; do
      [[ -r "$f" ]] && printf 'r' || printf '-'
      [[ -w "$f" ]] && printf 'w' || printf '-'
      [[ -x "$f" ]] && printf 'x' || printf '-'
      printf " %s\\n" "$f"
  done' _ "$@"

This should automatically take into account acl, if available, but the drawback is the use of sudo (or alternatively su) to become $user.