27.2.1 missing

The missing script is a wrapper around several maintainer tools, designed to warn users if a maintainer tool is required but missing. Typical maintainer tools are autoconf, automake, bison, etc. Because file generated by these tools are shipped with the other sources of a package, these tools shouldn't be required during a user build and they are not checked for in ‘configure’.

However, if for some reason a rebuild rule is triggered and involves a missing tool, missing will notice it and warn the user. Besides the warning, when a tool is missing, missing will attempt to fix timestamps in a way that allows the build to continue. For instance, missing will touch ‘configure’ if autoconf is not installed. When all distributed files are kept under CVS, this feature of missing allows user with no maintainer tools to build a package off CVS, bypassing any timestamp inconsistency implied by ‘cvs update’.

If the required tool is installed, missing will run it and won't attempt to continue after failures. This is correct during development: developers love fixing failures. However, users with wrong versions of maintainer tools may get an error when the rebuild rule is spuriously triggered, halting the build. This failure to let the build continue is one of the arguments of the AM_MAINTAINER_MODE advocates.