How to check for various software versions

Software	Command to find version
Linux kernel	cat /proc/version
IP firewall	ipfwadm -h
IP forwarding in kernel	Implemented if grep ip_forward /proc/ksyms finds anything Also (in later kernels) check /proc/sys/net/ipv4/ip_forward, which must be 1 for forwarding to work
modules	insmod -V
NFS	showmount --version
apache	httpd -v
GNU autoconf	autoconf --version
GNU automake	automake --version
GNU bash	bash --version
GNU bc	bc --version
binutils	ld -v
bison	bison --version
bzip2	bzip2 --help
diff	diff --version
dynamic linker (ld.so)	ldd -v
emacs	emacs --version
fileutils	cp --version
exim	exim -bV Thanks to Funk Gabor
find	find --version
flex	flex --version
gcc	gcc --version
grep	grep --version
gzip	gzip --version
less	less --version
libc	ls -l /lib/libc.so.*
lynx	lynx -version
make	make --version
man	man --version
mc (Midnight Commander)	mc --version
mirrordir	mirrordir --version
mount	mount --version
ncurses	ls -l /lib/libncurses.*
net-tools	hostname -V
patch	patch --version
perl	perl -v
procps	ps --version
samba	smbd -V
sed	sed --version
sh-utils	basename --v
tar	tar --version
termcap	ls -l /lib/libtermcap.so.*
wget	wget --version