> ! The standard shell interpreter `<tt>/bin/sh</tt>' is a > ! symbolic link to a POSIX compatible shell. Since the POSIX > ! standard for shells leaves important areas unspecified, > ! wherever it is lacking, `<tt>/bin/sh</tt>' shall follow the > ! <em>consensus behavior</em> of other shell interpreters. [snip] > ! Examples of behavior which is determined by consensus > ! include the effect of <tt>echo -n</tt>, and the initial > ! value of the <tt>IFS</tt> variable.
The meaning of POSIX will change from IEEE Std. 1003.2-1992 (ISO/IEC 9945-2:1993) to IEEE Std. 1003.1-200x in a not too distant future. The behavior of echo -n is defined in the current draft of IEEE Std. 1003.1-200x to print the string "-n", which is diffent from the current implementation in for example ash and bash. Therefore, if echo -n is portable on Linux today, it will probably not be during the move to the new standard. (For example /bin/sh in SunsOS 5.5 already has this new behavior.) I don't see what you mean by "the initial value of the IFS variable". Is there anything that is unspecified for field splitting in IEEE Std. 1003.2-1992? Isn't "If IFS is not set, the shell shall behave as if the value of IFS were the <space>, <tab>, and <newline> characters." (page 123) enough? My conclusion is that this concept of "consensus behavior" seems too fragile to be useful. -- Patrik Hägglund
