How to add prefix when sudo make install

[Firestar-Reimu]

The installation using make install recognizes the following
environment variables:

• prefix - Common installation prefix (default: /usr/local). The
  installation goes to ${prefix}/lib/iraf, with symlinks for the
  user-callable executables in ${prefix}/bin, and the manpages
  installed in ${prefix}/share/man. The iraf variable is set to
  ${prefix}/lib/iraf/.

I am going to install it to /usr/, but I don't know what can I run:

make install prefix=/usr/

or:

make install --prefix=/usr/

or:

make install -C /usr/

[olebole]

prefix is a recognized environment variable, so you can use

prefix=/usr make install

You can also set it separately (f.e. if other tools want to use it as well):

export prefix=/usr
make install

[Firestar-Reimu]

it seems that prefix=/usr make install make prefix=/usr install make install prefix=/usr are all OK?

[olebole]

They will all work, yes.