Bourne-shell incompatibilities
Wm E. Davidsen Jr
davidsen at sixhub.UUCP
Wed Jan 9 12:52:41 AEST 1991
In article <442 at minya.UUCP> jc at minya.UUCP (John Chambers) writes:
| Often only one of these is accepted by any particular /bin/sh, and the
| other is a syntax error. Sometimes both are accepted (with different
| meanings).
I don't dispute what you say, but I have never seen a sh which didn't
buy {$a-b} notation. Of course the meaning is different when both are
available, the whole : set of expansions was added about SysIII (my
SysIII system is down or I'd check).
${a-b} if $a is undefined use b instead
${a:-b} if $a is undefined *or null* use b instead
and so on for all the other operators.
--
bill davidsen - davidsen at sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
sysop *IX BBS and Public Access UNIX
moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -me
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