which (1) Linux Manual Page
NAME
which – locate a command
SYNOPSIS
which [-a] filename …
DESCRIPTION
which returns the pathnames of the files (or links) which would be executed in the current environment, had its arguments been given as commands in a strictly POSIX-conformant shell. It does this by searching the PATH for executable files matching the names of the arguments. It does not canonicalize path names.
OPTIONS
-a- print all matching pathnames of each argument
EXIT STATUS
0- if all specified commands are found and executable
1- if one or more specified commands is nonexistent or not executable
2- if an invalid option is specified