FAQ

Gordon Messmer wrote:


I'm reasonably certain that a script with no shebang will run with
/bin/sh. I interpret your statement to mean that if a user is using ksh
and enters the path to such a script, it would also run in ksh. That
would only be true if you "sourced" the script from your shell.

The historical way is: there is only one shell and all scripts are Bourne Shell
scripts.


Then csh came out and some people really thought is was a good idea to write
csh scripts. So someone decided to mark csh scripts with an initial "#".
Note that at that time, the Bourne Shell did not support "#" as a comment sign
and thus scripts with an inital "#" have been illegal Bourne Shell scripts.


Later BSD came out with #!name and all but AT&T adopted to this.


In the mid 1980s, AT&T introduced an initial ":" to mark Bourne Shell scripts.


In 1989, with the beginning of SVr4, even AT&T introduced #!name, but the AT&T
variant of the OS did not correct their scripts, so if you are on a UnixWare
installation, you will have fun.


Unfortunately, POSIX cannot standardize #!name. This is because POSIX does not
standardize PATHs and because the scripts marked that way would need to be
scripts that call the POSIX shell. The official method to get a POSIX shell is
to call this:


  sh # to make sure you have a Bourne Shell alike
  PATH=`getconf PATH` # to get a POSIX compliant PATH
  sh # to get a POSIX shell, that muust be the first
     # 'sh' in the POSIX PATH


/bin/sh definitely does not start a POSIX shell.....


J?rg


--
  EMail:joerg at schily.net (home) J?rg Schilling D-13353 Berlin
        joerg.schilling at fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
  URL: http://cdrecord.org/private/ http://sourceforge.net/projects/schilytools/files/'

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