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.
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.
Easy bootstrap "Gentoo Prefix" for several unix-like operating systems (Solaris, Linux, AIX, HP-UX, Interix, ...)