Some Useful Unix Tools

• man - display system documentation
• sh - the standard Unix (Bourne) shell
• cmp - compare files
• head - copy the first lines of a textfile
• tail - copy the last lines of textfile
• diff - compare two textfiles and show the differences
• wc - count the number of words, lines, etc. in a file
• cksum - compute a checksum for a file
• ulimit - set or report file size limit

The links above are to the 1997 Single Unix Specification (version 2), on the Open Group website. That is not the most recent version. I chose to link to the older version, out of conservativism. That standard has been out long enough that most Unix implementations have come into compliance with it, and changes to the standard generally are designed not to break existing code and shell scripts. Additional features provided in the newer version may not yet be widely supported.