A Tcl implementation of the cksum(1) command is now part of [Tcllib] and should end up in Tcllib 1.2. The cksum(1) command calculates a 32 bit checksum of the input data using a POSIX standard algorithm and so should give the same result across multiple platforms (unlike the [sum] command). The Tcllib version uses the same algorithm and has been checked against the GNU and BSD cksum(1) commands. More information about the unix command can be found at http://www.tac.eu.org/cgi-bin/man-cgi?cksum+1 or by referring to your system manual page. For example: % package require cksum 1.0 % crc::cksum "Hello, World!" 2609532967 % crc::cksum -file cksum.tcl 871033703 % exec cksum cksum.tcl 871033703 6652 cksum.tcl % ---- See the code at http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/tcllib/tcllib/modules/crc/cksum.tcl?rev=HEAD&content-type=text/vnd.viewcvs-markup ---- [Category Package] subset [Tcllib] see also [crc] and [sum]