File: make.info,  Node: Utilities in Makefiles,  Next: Command Variables,  Prev: Makefile Basics,  Up: Makefile Conventions

16.2 Utilities in Makefiles
===========================

Write the Makefile commands (and any shell scripts, such as 'configure')
to run under 'sh' (both the traditional Bourne shell and the POSIX
shell), not 'csh'.  Don't use any special features of 'ksh' or 'bash',
or POSIX features not widely supported in traditional Bourne 'sh'.

   The 'configure' script and the Makefile rules for building and
installation should not use any utilities directly except these:

     awk cat cmp cp diff echo expr false grep install-info ln ls
     mkdir mv printf pwd rm rmdir sed sleep sort tar test touch tr true

   Compression programs such as 'gzip' can be used in the 'dist' rule.

   Generally, stick to the widely-supported (usually POSIX-specified)
options and features of these programs.  For example, don't use 'mkdir
-p', convenient as it may be, because a few systems don't support it at
all and with others, it is not safe for parallel execution.  For a list
of known incompatibilities, see *note Portable Shell Programming:
(autoconf)Portable Shell.

   It is a good idea to avoid creating symbolic links in makefiles,
since a few file systems don't support them.

   The Makefile rules for building and installation can also use
compilers and related programs, but should do so via 'make' variables so
that the user can substitute alternatives.  Here are some of the
programs we mean:

     ar bison cc flex install ld ldconfig lex
     make makeinfo ranlib texi2dvi yacc

   Use the following 'make' variables to run those programs:

     $(AR) $(BISON) $(CC) $(FLEX) $(INSTALL) $(LD) $(LDCONFIG) $(LEX)
     $(MAKE) $(MAKEINFO) $(RANLIB) $(TEXI2DVI) $(YACC)

   When you use 'ranlib' or 'ldconfig', you should make sure nothing bad
happens if the system does not have the program in question.  Arrange to
ignore an error from that command, and print a message before the
command to tell the user that failure of this command does not mean a
problem.  (The Autoconf 'AC_PROG_RANLIB' macro can help with this.)

   If you use symbolic links, you should implement a fallback for
systems that don't have symbolic links.

   Additional utilities that can be used via Make variables are:

     chgrp chmod chown mknod

   It is ok to use other utilities in Makefile portions (or scripts)
intended only for particular systems where you know those utilities
exist.