BSD which implemented in Rust.
which [-as] program
The which utility takes a list of command names and searches the path for each executable file that would be run had these commands actu- ally been invoked.
The following options are available:
-a List all instances of executables found (instead of just the first one of each).
-s No output, just return 0 if any of the executables are found, or 1 if none are found.
holy crap is there any standardisation between implementations of which?