Portable Figure Out system properties
pofig - portable shell script for probing base system properties: OS, OS version, kernel version, distro, distro version, architecture. It detects: 19 operating systems, 11 major linux distros, 13 CPU types. See wiki for more information and examples.
Rex is a regular expression library which implements most of the POSIX 1003.2 specification. It is very mature and has been in heavy production use by thousands of users, on many platforms, since 2002.
Command validation tool
cmdok checks that specified commands are OK. If command is OK than it exists in PATH and can be run. It is a simple, small and portable Bash script. It is useful in software packages that want to check that some commands exist before trying to run them. See wiki for more information and examples.
C/C++ system probe, test and automation toolkit
cstem is a portable toolkit for probing and testing C/C++ system. It consist of 4 scripts: cprobe, cltest, cppdef, mkdep. cstem scripts can be used standalone or as part of software build systems. All scripts are portable and have no dependencies. See wiki for more information and examples.
msub - a Handy tool to read file(s) and perform substitutions using values of variables defined in makefile.