Path: utzoo!utgpu!watmath!uunet!tut.cis.ohio-state.edu!AUREL.CALTECH.EDU!bfox
From: bfox@AUREL.CALTECH.EDU (Brian Fox)
Newsgroups: gnu.bash.bug
Subject: parameter tests in Bourne shell
Message-ID: <8908241652.AA07471@aurel.caltech.edu>
Date: 24 Aug 89 16:52:19 GMT
References: <8908240229.AA18965@hub.ucsb.edu>
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   From: Jim Frew <frew%crseo@hub.ucsb.edu>
   Date: 23 Aug 1989 1927-PDT (Wednesday)

   In a recent bug-bash posting, cwjcc!kiwi!chet@gatech.edu (Chet Ramey) writes:

   > ... this behavior has been in the Bourne 
   > shell since its creation (i.e. 7th Edition).  Quoting from a random System
   > 5 release 2+ man page (this happens to be from Ultrix 3.0 sh5):
   >
   > ${parameter:?word}
   >          If parameter is set and is non-null, substitute its
   >          value; otherwise, print word and exit from the shell.
   >          If word is omitted, the message ``parameter null or not
   >          set'' is printed.
   >
   > The wording is essentially the same for the 4.3BSD sh, which means it was in
   > the 7th Edition sh.

   For the record, the use of ":" to test whether the parameter is null was NOT
   documented in the 7th Edition Bourne shell.  The V7 manual page sez:

	   ${parameter?word}
		   If parameter is set then substitute its value; otherwise,
		   print word and exit from the shell.  If word is omitted then a
		   standard message is printed.


The ":" isn't what we are complaining about, it is the "?" that is
causing the behaviour in question.

Brian Fox