4.2 Makefile syntax
`Makefile's have a rather particular syntax that can trouble new
users. There are many implementations of
make, some of which
provide non-portable extensions. An abridged description of the syntax
follows which, for portability, may be stricter than you may be used to.
Comments start with a `#' and continue until the end of line. They
may appear anywhere except in command sequences--if they do, they will
be interpreted by the shell running the command. The following
`Makefile' shows three individual targets with dependencies on
target1: dep1 dep2 ... depN
target2: dep4 dep5
Target rules start at the beginning of a line and are followed by a
colon. Following the colon is a whitespace separated list of
dependencies. A series of lines follow which contain shell commands
to be run by a sub-shell (the default is the Bourne shell). Each of
these lines must be prefixed by a horizontal tab character.
This is the most common mistake made by new
These commands may be prefixed by an `@' character to prevent
make from echoing the command line prior to executing it. They
may also optionally be prefixed by a `-' character to allow the
rule to continue if the command returns a non-zero exit code. The
combination of both characters is permitted.