#### which Procedure ¶

Searches the execution path for an executable file like the BSD `which(1)` utility. This procedure uses the shell environment variable `PATH`. It returns 0 if the binary is not in the path or if the `PATH` environment variable is not set. If the file is in the path, this procedure returns the full path to the file.

> `which file`

`file`

  The executable program or shell script to look for.