Module Name: src
Committed By: kre
Date: Mon Mar 20 22:17:56 UTC 2017
Modified Files:
src/bin/sh: sh.1
Log Message:
At the suggestion of Matthew Sporleder (on current-users@) reword some
of the description of arithmetic expressions to make it a bit more
human friendly.
While here fix a few other minor errors, and bump date.
To generate a diff of this commit:
cvs rdiff -u -r1.126 -r1.127 src/bin/sh/sh.1
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/bin/sh/sh.1
diff -u src/bin/sh/sh.1:1.126 src/bin/sh/sh.1:1.127
--- src/bin/sh/sh.1:1.126 Mon Mar 20 11:26:07 2017
+++ src/bin/sh/sh.1 Mon Mar 20 22:17:56 2017
@@ -1,4 +1,4 @@
-.\" $NetBSD: sh.1,v 1.126 2017/03/20 11:26:07 kre Exp $
+.\" $NetBSD: sh.1,v 1.127 2017/03/20 22:17:56 kre Exp $
.\" Copyright (c) 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
@@ -31,7 +31,7 @@
.\"
.\" @(#)sh.1 8.6 (Berkeley) 5/4/95
.\"
-.Dd February 1, 2017
+.Dd March 20, 2017
.Dt SH 1
.ds flags abCEeFfhnuvxIimpqV
.Os
@@ -1235,13 +1235,23 @@ The format for arithmetic expansion is a
.Pp
.Dl $((expression))
.Pp
-The expression is treated as if it were in double quotes, except
-that a double quote inside the expression is not treated specially.
+The expression in an arithmetic expansion is treated as if it were in
+double quotes, except that a double quote character inside the expression
+is just a normal character (it quotes nothing.)
The shell expands all tokens in the expression for parameter expansion,
-command substitution, and quote removal.
+command substitution, and quote removal (the only quoting character is
+the backslash
+.Sq \&\e ,
+and only when followed by another
+.Sq \&\e ,
+a dollar sign
+.Sq \&$ ,
+a backquote
+.Sq \&`
+or a newline.)
.Pp
-Next, the shell treats this as an arithmetic expression and
-substitutes the value of the expression.
+Next, the shell evaluates the expanded result as an arithmetic expression
+and substitutes the calculated value of that expression.
.Pp
Arithmetic expressions use a syntax similar to that
of the C language, and are evaluated using the
@@ -1250,7 +1260,7 @@ data type (this is an extension to
.Tn POSIX ,
which requires only
.Ql long
-arithmetic).
+arithmetic.)
Shell variables may be referenced by name inside an arithmetic
expression, without needing a
.Dq \&$
@@ -1595,7 +1605,7 @@ environment of subsequent commands.
With
.Fl n
the specified names are un-exported.
-Variables can also be un-exported using the unset builtin command.
+Variables can also be un-exported using the unset built in command.
With
.Fl x
(exclude) the specified names are marked not to be exported,
@@ -2216,7 +2226,7 @@ its exit status will be greater than 128
Once waited upon, by specific process number or job-id,
or by a
.Ic wait
-with no argumentss,
+with no arguments,
knowledge of the child is removed from the system,
and it cannot be waited upon again.
.El
