will output /usr/bin/gcc, where gcc is the program we are looking for.
for more info about this command:
will display this:
which - locate a command
which [-a] filename ...
which returns the pathnames of the files (or links) which would be exeâ
cuted in the current environment, had its arguments been given as comâ
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 follow symbolic links.
-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 exeâ
2 if an invalid option is specified