Ask for one of several types and read the first character

Answer

ls -ld / /tmp /etc/passwd ls -l /dev/null /dev/loop0 ls -ld /run/docker.sock

Three type characters in three commands: d and - from the first, c and b from the second, s from the third. `-d` makes `ls` describe a directory instead of listing what is inside it — without it the first line would dump the whole root directory.

Sarwar & Koretsky 3e ch4 §4.2-4.3