Hitchhiker's Guide to the Internet is a German introduction to the technical aspects of the Internet. This book explains both the low-level protocols IP, ICMP, TCP, and UDP and the high-level protocols SMTP, POP3, IMAP4, NNTP, HTTP, Gopher, FTP, IRC, DICT, Finger, Daytime, DNS, and Whois.
The Heirloom Toolchest is a collection of standard Unix utilities. It was derived from original Unix material released as open source by Caldera and Sun, and contains multiple versions of each utility corresponding to SVID3/SVR4, SVID4/SVR4.2MP, POSIX.2-1992/SUSV2, POSIX.1-2001/SUSV3, and 4BSD (SVR4 /usr/ucb). It processes lines of arbitrary length and in many cases binary input data, supports characters in UTF-8 and many East Asian encodings, and contains more than 100 individual utilities including bc, cpio, diff, ed, file, find, grep, man, nawk, oawk, pax, ps, sed, sort, spell, and tar. Extensive documentation is included.