WHICH(1) General Commands Manual WHICH(1)
which - locate a command
which [-a] filename ...
which returns the pathnames of the files (or links) which would be exe-
cuted in the current environment, had its arguments been given as com-
mands 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.
-a print all matching pathnames of each argument
0 if all specified commands are found and executable
1 if one or more specified commands is nonexistent or not exe-
2 if an invalid option is specified
Debian 29 Jun 2016 WHICH(1)