Last checked against version &autoconf-contversion;. autoconf, autoheader, autom4te, autoreconf, autoscan, autoupdate and ifnames autoconf is a tool for producing shell scripts that automatically configure software source code packages to adapt to many kinds of Unix-like systems. The configuration scripts produced by autoconf are independent of autoconf when they are run, so their users do not need to have autoconf. The autoheader program can create a template file of C #define statements for configure to use. autom4te runs GNU M4 on files. If there are a lot of autoconf-generated configure scripts, the autoreconf program can save some work. It runs autoconf and autoheader (where appropriate) repeatedly to remake the autoconf configure scripts and configuration header templates in the directory tree rooted at the current directory. The autoscan program can help to create a configure.in file for a software package. autoscan examines the source files in a directory tree. If a directory is not specified on the command line, then the current working directory is used. The source files are searched for common portability problems and a configure.scan file is created to serve as the preliminary configure.in for that package. The autoupdate program updates a configure.in file that calls autoconf macros by their old names to use the current macro names. ifnames can help when writing a configure.in for a software package. It prints the identifiers that the package already uses in C preprocessor conditionals. If a package has already been set up to have some portability, this program can help to determine what configure needs to check. It may fill in some gaps in a configure.in file generated by autoscan.