the #! notation

[Andrew H. Marrinson]

davidsen at sixhub.UUCP (Wm E. Davidsen Jr) writes:

>  It seems to me
>there's a mechanism in SysV which put a line like

>	: uses /bin/csh

>as the first line, but I can't remember where I saw it.

Just to clear up a common misconception here.  I know of no shell that
allows anything resembling ``: use some_program'' to specify an
arbitrary interpreter like the #! syntax does.  The idea that this
works seems to have come from Larry Wall's configure script, which
checks to see if #!/bin/sh arranges for scripts to be executed by
Bourne shell, and if that fails, checks : use /bin/sh.  The latter is
used because some older cshs (especially on system V and similar
Unixes that lack #!) treat scripts beginning with # as csh scripts
while scripts beginning with any other character are executed with
/bin/sh.  It is the ``:'' that is significant in this case.  The
phrase ``use /bin/sh'' is just a comment.
--
		Andrew H. Marrinson
		Icom Systems, Inc.
		Wheeling, IL, USA
		(andy at icom.icom.com)