Date: Thu, 2 Nov 2006 18:31:12 GMT From: Ed Maste <emaste@FreeBSD.org> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/105078: sh(1) aborts on invalid substitution in a not-taken if statement Message-ID: <200611021831.kA2IVCTB069784@freefall.freebsd.org> Resent-Message-ID: <200611021840.kA2IeH9V071424@freefall.freebsd.org>
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>Number: 105078
>Category: bin
>Synopsis: sh(1) aborts on invalid substitution in a not-taken if statement
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Nov 02 18:40:17 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator: Ed Maste
>Release: FreeBSD 6.0-STABLE i386
>Organization:
FreeBSD
>Environment:
System: FreeBSD freefall.freebsd.org 6.0-STABLE FreeBSD 6.0-STABLE #0: Sat Dec 10 03:18:20 UTC 2005 kensmith@freefall.freebsd.org:/usr/obj/usr/src/sys/FREEFALL i386
>Description:
It seems our sh(1) attempts to evaluate variable substitutions inside of an if statement
even if the statement evaluates to false.
I discovered this with a shell script that encapsulated some Linux sh-isms inside of a
check based on uname -s, and our sh aborted on those statements. That shell script was
using a substring of the form ${var:1:3}, but I've used an intentionally bogus
substitution of ${} in the example below.
For reference, I observed the same behaviour with NetBSD's sh. My Debian box produced
no error. (I'm not sure what sh variant it has installed as /bin/sh.) Solaris 10 was
also silent (thanks rwatson for checking).
>How-To-Repeat:
$ /bin/sh -c 'if false; then x=${}; fi'
Syntax error: Bad substitution
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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