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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.
This commit is contained in:
kre 2017-03-20 22:17:56 +00:00
parent 0fb210a2c1
commit 996a70951c
1 changed files with 20 additions and 10 deletions
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30
bin/sh/sh.1
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@ -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 as follows:
.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