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Document an interesting kwirk in := handling of undefined variables.

This commit is contained in:
sjg 2006-03-19 01:53:01 +00:00
parent 3040914cf6
commit 8af5ec82ab
1 changed files with 6 additions and 2 deletions
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8
usr.bin/make/make.1
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@ -1,4 +1,4 @@
.\" $NetBSD: make.1,v 1.123 2006/03/11 12:02:20 wiz Exp $
.\" $NetBSD: make.1,v 1.124 2006/03/19 01:53:01 sjg Exp $
.\"
.\" Copyright (c) 1990, 1993
.\" The Regents of the University of California. All rights reserved.
@ -29,7 +29,7 @@
.\"
.\" from: @(#)make.1 8.4 (Berkeley) 3/19/94
.\"
.Dd February 26, 2006
.Dd March 18, 2006
.Dt MAKE 1
.Os
.Sh NAME
@ -417,6 +417,10 @@ Assign the value to the variable if it is not already defined.
Assign with expansion, i.e. expand the value before assigning it
to the variable.
Normally, expansion is not done until the variable is referenced.
.Em NOTE :
References to undefined variables are
.Em not
expanded. This can cause problems when variable modifiers are used.
.It Ic \&!=
Expand the value and pass it to the shell for execution and assign
the result to the variable.