Date: Sun, 19 Sep 2010 21:38:12 +0000 (UTC) From: Jilles Tjoelker <jilles@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org Subject: svn commit: r212884 - stable/8/bin/sh Message-ID: <201009192138.o8JLcCpC017472@svn.freebsd.org>
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Author: jilles Date: Sun Sep 19 21:38:12 2010 New Revision: 212884 URL: http://svn.freebsd.org/changeset/base/212884 Log: MFC r211621: sh(1): Add a brief summary of arithmetic expressions. Modified: stable/8/bin/sh/sh.1 Directory Properties: stable/8/bin/sh/ (props changed) Modified: stable/8/bin/sh/sh.1 ============================================================================== --- stable/8/bin/sh/sh.1 Sun Sep 19 20:38:34 2010 (r212883) +++ stable/8/bin/sh/sh.1 Sun Sep 19 21:38:12 2010 (r212884) @@ -1148,7 +1148,7 @@ Quote Removal. The .Ql $ character is used to introduce parameter expansion, command -substitution, or arithmetic evaluation. +substitution, or arithmetic expansion. .Ss Tilde Expansion (substituting a user's home directory) A word beginning with an unquoted tilde character .Pq Ql ~ @@ -1363,10 +1363,41 @@ The shell expands all tokens in the .Ar expression for parameter expansion, -command substitution, and quote removal. +command substitution, +arithmetic expansion +and quote removal. +.Pp +The allowed expressions are a subset of C expressions, +summarized below. +.Bl -tag -width "Variables" -offset indent +.It Values +All values are of type +.Ft intmax_t . +.It Constants +Decimal, octal (starting with +.Li 0 ) +and hexadecimal (starting with +.Li 0x ) +integer constants. +.It Variables +Shell variables can be read and written +and contain integer constants. +.It Unary operators +.Li "! ~ + -" +.It Binary operators +.Li "* / % + - << >> < <= > >= == != & ^ | && ||" +.It Assignment operators +.Li "= += -= *= /= %= <<= >>= &= ^= |=" +.It Short-circuit evaluation +The +.Li && +and +.Li || +operators always evaluate both sides. +This is a bug. +.El .Pp -Next, the shell treats this as an arithmetic expression and -substitutes the value of the expression. +The result of the expression is substituted in decimal. .Ss White Space Splitting (Field Splitting) After parameter expansion, command substitution, and arithmetic expansion the shell scans the results ofhome | help
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