The following commands will return a true value (exit code of 0) if you are using an instruction set that the command name indicates.

sun

True if you are on a Sun system.

iAPX286

True if you are on a computer using an iAPX286 processor.

i386

True if you are on a computer using an iAPX386 processor.

pdp11

True if you are on a PDP-11/45(TM) or PDP-11/70(TM).

sparc

True if you are on a computer using a SPARC-family processor.

u3b

True if you are on a 3B20 computer.

u3b2

True if you are on a 3B2 computer.

u3b5

True if you are on a 3B5 computer.

u3b15

True if you are on a 3B15 computer.

vax

True if you are on a VAX-11/750(TM) or VAX-11/780(TM).

u370

True if you are on an IBM\256 System/370(TM) computer.

The commands that do not apply will return a false (non-zero) value. These commands are often used within makefiles (see make(1S)) and shell scripts (see sh(1)) to increase portability.

See attributes(5) for descriptions of the following attributes:

make(1S), sh(1), test(1), true(1), uname(1), attributes(5)

The machid family of commands is obsolete. Use uname -p and uname -m instead.