656 lines
38 KiB
HTML
656 lines
38 KiB
HTML
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<head>
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<title>rc(1) - Plan 9 from User Space</title>
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<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
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</head>
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<body bgcolor=#ffffff>
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=10><td>
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<tr><td width=20><td>
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<tr><td width=20><td><b>RC(1)</b><td align=right><b>RC(1)</b>
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<tr><td width=20><td colspan=2>
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<br>
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<p><font size=+1><b>NAME </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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rc, cd, eval, exec, exit, flag, rfork, shift, wait, whatis, .,
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~ – command language<br>
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</table>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>rc</font></tt> [ <tt><font size=+1>−srdiIlxepvV</font></tt> ] [ <tt><font size=+1>−c command</font></tt> ] [ <i>file</i> [ <i>arg ...</i> ]]<br>
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</table>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<i>Rc</i> is the Plan 9 shell. It executes command lines read from a
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terminal or a file or, with the <tt><font size=+1>−c</font></tt> flag, from <i>rc’s</i> argument list.<br>
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<p><font size=+1><b>Command Lines </b></font><br>
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A command line is a sequence of commands, separated by ampersands
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or semicolons (<tt><font size=+1>&</font></tt> or <tt><font size=+1>;</font></tt>), terminated by a newline. The commands are
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executed in sequence from left to right. <i>Rc</i> does not wait for
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a command followed by <tt><font size=+1>&</font></tt> to finish executing before starting the
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following command. Whenever a command
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followed by <tt><font size=+1>&</font></tt> is executed, its process id is assigned to the <i>rc</i>
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variable <tt><font size=+1>$apid</font></tt>. Whenever a command <i>not</i> followed by <tt><font size=+1>&</font></tt> exits or is
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terminated, the <i>rc</i> variable <tt><font size=+1>$status</font></tt> gets the process’s wait message
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(see <a href="../man3/wait.html"><i>wait</i>(3)</a>); it will be the null string if the command was successful.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A long command line may be continued on subsequent lines by typing
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a backslash (<tt><font size=+1>\</font></tt>) followed by a newline. This sequence is treated
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as though it were a blank. Backslash is not otherwise a special
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character.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A number-sign (<tt><font size=+1>#</font></tt>) and any following characters up to (but not
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including) the next newline are ignored, except in quotation marks.<br>
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<p><font size=+1><b>Simple Commands </b></font><br>
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A simple command is a sequence of arguments interspersed with
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I/O redirections. If the first argument is the name of an <i>rc</i> function
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or of one of <i>rc’s</i> built-in commands, it is executed by <i>rc</i>. Otherwise
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if the name starts with a slash (<tt><font size=+1>/</font></tt>), it must be the path name
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of the program to be executed. Names containing no
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initial slash are searched for in a list of directory names stored
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in <tt><font size=+1>$path</font></tt>. The first executable file of the given name found in
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a directory in <tt><font size=+1>$path</font></tt> is the program to be executed. To be executable,
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the user must have execute permission (see <a href="../man3/stat.html"><i>stat</i>(3)</a>) and the file
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must be either an executable binary for the current
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machine’s CPU type, or a shell script. Shell scripts begin with
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a line containing the full path name of a shell (usually <tt><font size=+1>/bin/rc</font></tt>),
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prefixed by <tt><font size=+1>#!</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The first word of a simple command cannot be a keyword unless
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it is quoted or otherwise disguised. The keywords are<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>for in while if not switch fn ~ ! @<br>
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</font></tt>
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</table>
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<p><font size=+1><b>Arguments and Variables </b></font><br>
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A number of constructions may be used where <i>rc’s</i> syntax requires
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an argument to appear. In many cases a construction’s value will
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be a list of arguments rather than a single string.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The simplest kind of argument is the unquoted word: a sequence
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of one or more characters none of which is a blank, tab, newline,
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or any of the following:<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1># ; & | ^ $ = ` ' { } ( ) < ><br>
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</font></tt>
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</table>
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An unquoted word that contains any of the characters <tt><font size=+1>* ? [</font></tt> is
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a pattern for matching against file names. The character <tt><font size=+1>*</font></tt> matches
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any sequence of characters, <tt><font size=+1>?</font></tt> matches any single character, and
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<tt><font size=+1>[</font></tt><i>class</i><tt><font size=+1>]</font></tt> matches any character in the <i>class</i>. If the first character
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of <i>class</i> is <tt><font size=+1>~</font></tt>, the class is complemented. The <i>class</i> may
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also contain pairs of characters separated by <tt><font size=+1>−</font></tt>, standing for
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all characters lexically between the two. The character <tt><font size=+1>/</font></tt> must
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appear explicitly in a pattern, as must the first character of
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the path name components <tt><font size=+1>.</font></tt> and <tt><font size=+1>..</font></tt>. A pattern is replaced by a
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list of arguments, one for each path name matched, except that
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a
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pattern matching no names is not replaced by the empty list, but
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rather stands for itself. Pattern matching is done after all other
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operations. Thus,<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>x=/tmp echo $x^/*.c<br>
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</font></tt>
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</table>
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matches <tt><font size=+1>/tmp/*.c</font></tt>, rather than matching <tt><font size=+1>/*.c</font></tt> and then prefixing
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<tt><font size=+1>/tmp</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A quoted word is a sequence of characters surrounded by single
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quotes (<tt><font size=+1>'</font></tt>). A single quote is represented in a quoted word by
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a pair of quotes (<tt><font size=+1>''</font></tt>).
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Each of the following is an argument.<br>
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<tt><font size=+1>(</font></tt><i>arguments</i><tt><font size=+1>)<br>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The value of a sequence of arguments enclosed in parentheses is
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a list comprising the members of each element of the sequence.
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Argument lists have no recursive structure, although their syntax
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may suggest it. The following are entirely equivalent:<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>echo hi there everybody<br>
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((echo) (hi there) everybody)<br>
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</font></tt>
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</table>
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</table>
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<tt><font size=+1>$</font></tt><i>argument<br>
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</i><tt><font size=+1>$</font></tt><i>argument</i><tt><font size=+1>(</font></tt><i>subscript</i><tt><font size=+1>)<br>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The <i>argument</i> after the <tt><font size=+1>$</font></tt> is the name of a variable whose value
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is substituted. Multiple levels of indirection are possible, but
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of questionable utility. Variable values are lists of strings.
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If <i>argument</i> is a number <i>n</i>, the value is the <i>n</i>th element of <tt><font size=+1>$*</font></tt>,
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unless <tt><font size=+1>$*</font></tt> doesn’t have <i>n</i> elements, in which case the value is
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empty. If <i>argument</i> is followed by a parenthesized list of subscripts,
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the value substituted is a list composed of the requested elements
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(origin 1). The parenthesis must follow the variable name with
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no spaces. Assignments to variables are described below.<br>
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</table>
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<tt><font size=+1>$#</font></tt><i>argument<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The value is the number of elements in the named variable. A variable
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never assigned a value has zero elements.<br>
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</table>
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$"<i>argument<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The value is a single string containing the components of the
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named variable separated by spaces. A variable with zero elements
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yields the empty string.<br>
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</table>
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<tt><font size=+1>`{</font></tt><i>command</i><tt><font size=+1>}<br>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<i>rc</i> executes the <i>command</i> and reads its standard output, splitting
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it into a list of arguments, using characters in <tt><font size=+1>$ifs</font></tt> as separators.
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If <tt><font size=+1>$ifs</font></tt> is not otherwise set, its value is <tt><font size=+1>' \t\n'</font></tt>.<br>
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</table>
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<tt><font size=+1><{</font></tt><i>command</i><tt><font size=+1>}<br>
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>{</font></tt><i>command</i><tt><font size=+1>}<br>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The <i>command</i> is executed asynchronously with its standard output
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or standard input connected to a pipe. The value of the argument
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is the name of a file referring to the other end of the pipe.
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This allows the construction of non-linear pipelines. For example,
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the following runs two commands <tt><font size=+1>old</font></tt> and <tt><font size=+1>new
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</font></tt>and uses <tt><font size=+1>cmp</font></tt> to compare their outputs<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>cmp <{old} <{new}<br>
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</font></tt>
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</table>
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</table>
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<i>argument</i><tt><font size=+1>^</font></tt><i>argument<br>
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</i>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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The <tt><font size=+1>^</font></tt> operator concatenates its two operands. If the two operands
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have the same number of components, they are concatenated pairwise.
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If not, then one operand must have one component, and the other
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must be non-empty, and concatenation is distributive.<br>
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</table>
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<p><font size=+1><b>Free Carets </b></font><br>
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In most circumstances, <i>rc</i> will insert the <tt><font size=+1>^</font></tt> operator automatically
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between words that are not separated by white space. Whenever
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one of <tt><font size=+1>$ ' `</font></tt> follows a quoted or unquoted word or an unquoted
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word follows a quoted word with no intervening blanks or tabs,
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a <tt><font size=+1>^</font></tt> is inserted between the two. If an unquoted word
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immediately follows a <tt><font size=+1>$</font></tt> and contains a character other than an
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alphanumeric, underscore, or <tt><font size=+1>*</font></tt>, a <tt><font size=+1>^</font></tt> is inserted before the first
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such character. Thus<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>cc −$flags $stem.c
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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</font></tt>
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</table>
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is equivalent to<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<tt><font size=+1>cc −^$flags $stem^.c<br>
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</font></tt>
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</table>
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<p><font size=+1><b>I/O Redirections </b></font><br>
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The sequence <tt><font size=+1>></font></tt><i>file</i> redirects the standard output file (file descriptor
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1, normally the terminal) to the named <i>file</i>; <tt><font size=+1>>></font></tt><i>file</i> appends standard
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output to the file. The standard input file (file descriptor 0,
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also normally the terminal) may be redirected from a file by the
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sequence <tt><font size=+1><</font></tt><i>file</i>, or from an inline ‘here document’ by the
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sequence <tt><font size=+1><<</font></tt><i>eof-marker</i>. The contents of a here document are lines
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of text taken from the command input stream up to a line containing
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nothing but the <i>eof-marker</i>, which may be either a quoted or unquoted
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word. If <i>eof-marker</i> is unquoted, variable names of the form <tt><font size=+1>$</font></tt><i>word</i>
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have their values substituted from <i>rc’s
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</i>environment. If <tt><font size=+1>$</font></tt><i>word</i> is followed by a caret (<tt><font size=+1>^</font></tt>), the caret is
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deleted. If <i>eof-marker</i> is quoted, no substitution occurs.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Redirections may be applied to a file-descriptor other than standard
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input or output by qualifying the redirection operator with a
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number in square brackets. For example, the diagnostic output
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(file descriptor 2) may be redirected by writing <tt><font size=+1>cc junk.c >[2]junk</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A file descriptor may be redirected to an already open descriptor
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by writing <tt><font size=+1>>[</font></tt><i>fd0</i><tt><font size=+1>=</font></tt><i>fd1</i><tt><font size=+1>]</font></tt> or <tt><font size=+1><[</font></tt><i>fd0</i><tt><font size=+1>=</font></tt><i>fd1</i><tt><font size=+1>]</font></tt>. <i>Fd1</i> is a previously opened
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file descriptor and <i>fd0</i> becomes a new copy (in the sense of <a href="../man3/dup.html"><i>dup</i>(3)</a>)
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of it. A file descriptor may be closed by writing <tt><font size=+1>>[</font></tt><i>fd0</i><tt><font size=+1>=]</font></tt> or <tt><font size=+1><[</font></tt><i>fd0</i><tt><font size=+1>=]</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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Redirections are executed from left to right. Therefore, <tt><font size=+1>cc junk.c
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>/dev/null >[2=1]</font></tt> and <tt><font size=+1>cc junk.c >[2=1] >/dev/null</font></tt> have different effects:
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the first puts standard output in <tt><font size=+1>/dev/null</font></tt> and then puts diagnostic
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output in the same place, where the second directs diagnostic
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output to the
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terminal and sends standard output to <tt><font size=+1>/dev/null</font></tt>.<br>
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<p><font size=+1><b>Compound Commands </b></font><br>
|
||
|
|
A pair of commands separated by a pipe operator (<tt><font size=+1>|</font></tt>) is a command.
|
||
|
|
The standard output of the left command is sent through a pipe
|
||
|
|
to the standard input of the right command. The pipe operator
|
||
|
|
may be decorated to use different file descriptors. <tt><font size=+1>|[</font></tt><i>fd</i><tt><font size=+1>]</font></tt> connects
|
||
|
|
the output end of the pipe to file descriptor <i>fd</i> rather
|
||
|
|
than 1. <tt><font size=+1>|[</font></tt><i>fd0</i><tt><font size=+1>=</font></tt><i>fd1</i><tt><font size=+1>]</font></tt> connects output to <i>fd1</i> of the left command
|
||
|
|
and input to <i>fd0</i> of the right command.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
A pair of commands separated by <tt><font size=+1>&&</font></tt> or <tt><font size=+1>||</font></tt> is a command. In either
|
||
|
|
case, the left command is executed and its exit status examined.
|
||
|
|
If the operator is <tt><font size=+1>&&</font></tt> the right command is executed if the left
|
||
|
|
command’s status is null. <tt><font size=+1>||</font></tt> causes the right command to be executed
|
||
|
|
if the left command’s status is non-null.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
The exit status of a command may be inverted (non-null is changed
|
||
|
|
to null, null is changed to non-null) by preceding it with a <tt><font size=+1>!</font></tt>.
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
The <tt><font size=+1>|</font></tt> operator has highest precedence, and is left-associative
|
||
|
|
(i.e. binds tighter to the left than the right). <tt><font size=+1>!</font></tt> has intermediate
|
||
|
|
precedence, and <tt><font size=+1>&&</font></tt> and <tt><font size=+1>||</font></tt> have the lowest precedence.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
The unary <tt><font size=+1>@</font></tt> operator, with precedence equal to <tt><font size=+1>!</font></tt>, causes its operand
|
||
|
|
to be executed in a subshell.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
Each of the following is a command.<br>
|
||
|
|
<tt><font size=+1>if (</font></tt> <i>list</i> <tt><font size=+1>)</font></tt> <i>command<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
A <i>list</i> is a sequence of commands, separated by <tt><font size=+1>&</font></tt>, <tt><font size=+1>;</font></tt>, or newline.
|
||
|
|
It is executed and if its exit status is null, the <i>command</i> is
|
||
|
|
executed.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>if not</font></tt> <i>command<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The immediately preceding command must have been <tt><font size=+1>if(</font></tt><i>list</i><tt><font size=+1>)</font></tt> <i>command</i>.
|
||
|
|
If its condition was non-zero, the <i>command</i> is executed.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>for(</font></tt><i>name</i> <tt><font size=+1>in</font></tt> <i>arguments</i><tt><font size=+1>)</font></tt> <i>command<br>
|
||
|
|
</i><tt><font size=+1>for(</font></tt><i>name</i><tt><font size=+1>)</font></tt> <i>command<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The <i>command</i> is executed once for each <i>argument</i> with that argument
|
||
|
|
assigned to <i>name</i>. If the argument list is omitted, <tt><font size=+1>$*</font></tt> is used.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>while(</font></tt><i>list</i><tt><font size=+1>)</font></tt> <i>command<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The <i>list</i> is executed repeatedly until its exit status is non-null.
|
||
|
|
Each time it returns null status, the <i>command</i> is executed. An
|
||
|
|
empty <i>list</i> is taken to give null status.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>switch(</font></tt><i>argument</i><tt><font size=+1>){</font></tt><i>list</i><tt><font size=+1>}<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The <i>list</i> is searched for simple commands beginning with the word
|
||
|
|
<tt><font size=+1>case</font></tt>. (The search is only at the ‘top level’ of the <i>list</i>. That
|
||
|
|
is, <tt><font size=+1>cases</font></tt> in nested constructs are not found.) <i>Argument</i> is matched
|
||
|
|
against each word following <tt><font size=+1>case</font></tt> using the pattern-matching algorithm
|
||
|
|
described above, except that <tt><font size=+1>/</font></tt> and the
|
||
|
|
first characters of <tt><font size=+1>.</font></tt> and <tt><font size=+1>..</font></tt> need not be matched explicitly. When
|
||
|
|
a match is found, commands in the list are executed up to the
|
||
|
|
next following <tt><font size=+1>case</font></tt> command (at the top level) or the closing
|
||
|
|
brace.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>{</font></tt><i>list</i><tt><font size=+1>}<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Braces serve to alter the grouping of commands implied by operator
|
||
|
|
priorities. The <i>body</i> is a sequence of commands separated by <tt><font size=+1>&</font></tt>,
|
||
|
|
<tt><font size=+1>;</font></tt>, or newline.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>fn</font></tt> <i>name</i><tt><font size=+1>{</font></tt><i>list</i><tt><font size=+1>}<br>
|
||
|
|
fn</font></tt> <i>name<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The first form defines a function with the given <i>name</i>. Subsequently,
|
||
|
|
whenever a command whose first argument is <i>name</i> is encountered,
|
||
|
|
the current value of the remainder of the command’s argument list
|
||
|
|
will be assigned to <tt><font size=+1>$*</font></tt>, after saving its current value, and <i>rc</i>
|
||
|
|
will execute the <i>list</i>. The second form removes
|
||
|
|
<i>name</i>’s function definition.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>fn</font></tt> <i>note</i><tt><font size=+1>{</font></tt><i>list</i><tt><font size=+1>}<br>
|
||
|
|
fn</font></tt> <i>note<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
A function with a special name will be called when <i>rc</i> receives
|
||
|
|
a corresponding note; see <a href="../man3/notify.html"><i>notify</i>(3)</a>. The valid note names (and
|
||
|
|
corresponding notes) are <tt><font size=+1>sighup</font></tt> (<tt><font size=+1>hangup</font></tt>), <tt><font size=+1>sigint</font></tt> (<tt><font size=+1>interrupt</font></tt>),
|
||
|
|
<tt><font size=+1>sigalrm</font></tt> (<tt><font size=+1>alarm</font></tt>), and <tt><font size=+1>sigfpe</font></tt> (floating point trap). By default
|
||
|
|
<i>rc</i> exits on receiving any signal, except when
|
||
|
|
run interactively, in which case interrupts and quits normally
|
||
|
|
cause <i>rc</i> to stop whatever it’s doing and start reading a new command.
|
||
|
|
The second form causes <i>rc</i> to handle a signal in the default manner.
|
||
|
|
<i>Rc</i> recognizes an artificial note, <tt><font size=+1>sigexit</font></tt>, which occurs when <i>rc</i>
|
||
|
|
is about to finish executing.
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<i>name</i><tt><font size=+1>=</font></tt><i>argument command<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Any command may be preceded by a sequence of assignments interspersed
|
||
|
|
with redirections. The assignments remain in effect until the
|
||
|
|
end of the command, unless the command is empty (i.e. the assignments
|
||
|
|
stand alone), in which case they are effective until rescinded
|
||
|
|
by later assignments.
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<p><font size=+1><b>Built-in Commands </b></font><br>
|
||
|
|
These commands are executed internally by <i>rc</i>, usually because
|
||
|
|
their execution changes or depends on <i>rc</i>’s internal state.<br>
|
||
|
|
<tt><font size=+1>.</font></tt> <i>file ...<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Execute commands from <i>file</i>. <tt><font size=+1>$*</font></tt> is set for the duration to the
|
||
|
|
remainder of the argument list following <i>file</i>. <i>File</i> is searched
|
||
|
|
for using <tt><font size=+1>$path</font></tt>.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>builtin</font></tt> <i>command ...<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Execute <i>command</i> as usual except that any function named <i>command</i>
|
||
|
|
is ignored in favor of the built-in meaning.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>cd [</font></tt><i>dir</i><tt><font size=+1>]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Change the current directory to <i>dir</i>. The default argument is <tt><font size=+1>$home</font></tt>.
|
||
|
|
<i>dir</i> is searched for in each of the directories mentioned in <tt><font size=+1>$cdpath</font></tt>.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>eval [</font></tt><i>arg ...</i><tt><font size=+1>]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The arguments are concatenated separated by spaces into a single
|
||
|
|
string, read as input to <i>rc</i>, and executed.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>exec [</font></tt><i>command ...</i><tt><font size=+1>]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
This instance of <i>rc</i> replaces itself with the given (non-built-in)
|
||
|
|
<i>command</i>.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>flag</font></tt> <i>f</i> <tt><font size=+1>[+−]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Either set (<tt><font size=+1>+</font></tt>), clear (<tt><font size=+1>−</font></tt>), or test (neither <tt><font size=+1>+</font></tt> nor <tt><font size=+1>−</font></tt>) the flag
|
||
|
|
<i>f</i>, where <i>f</i> is a single character, one of the command line flags
|
||
|
|
(see Invocation, below).<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>exit [</font></tt><i>status</i><tt><font size=+1>]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Exit with the given exit status. If none is given, the current
|
||
|
|
value of <tt><font size=+1>$status</font></tt> is used.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>rfork</font></tt> [<tt><font size=+1>nNeEsfFm</font></tt>]<br>
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Become a new process group using <tt><font size=+1>rfork(</font></tt><i>flags</i><tt><font size=+1>)</font></tt> where <i>flags</i> is composed
|
||
|
|
of the bitwise OR of the <tt><font size=+1>rfork</font></tt> flags specified by the option letters
|
||
|
|
(see <a href="../man2/fork.html"><i>fork</i>(2)</a>). If no <i>flags</i> are given, they default to <tt><font size=+1>ens</font></tt>. The
|
||
|
|
<i>flags</i> and their meanings are: <tt><font size=+1>n</font></tt> is <tt><font size=+1>RFNAMEG</font></tt>; <tt><font size=+1>N</font></tt> is <tt><font size=+1>RFCNAMEG</font></tt>; <tt><font size=+1>e</font></tt> is
|
||
|
|
<tt><font size=+1>RFENVG</font></tt>; <tt><font size=+1>E</font></tt> is <tt><font size=+1>RFCENVG</font></tt>; <tt><font size=+1>s</font></tt> is
|
||
|
|
<tt><font size=+1>RFNOTEG</font></tt>; <tt><font size=+1>f</font></tt> is <tt><font size=+1>RFFDG</font></tt>; <tt><font size=+1>F</font></tt> is <tt><font size=+1>RFCFDG</font></tt>; and <tt><font size=+1>m</font></tt> is <tt><font size=+1>RFNOMNT</font></tt>.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>shift [</font></tt><i>n</i><tt><font size=+1>]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Delete the first <i>n</i> (default 1) elements of <tt><font size=+1>$*</font></tt>.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>wait [</font></tt><i>pid</i><tt><font size=+1>]<br>
|
||
|
|
</font></tt>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Wait for the process with the given <i>pid</i> to exit. If no <i>pid</i> is
|
||
|
|
given, all outstanding processes are waited for.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>whatis</font></tt> <i>name ...<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Print the value of each <i>name</i> in a form suitable for input to <i>rc</i>.
|
||
|
|
The output is an assignment to any variable, the definition of
|
||
|
|
any function, a call to <tt><font size=+1>builtin</font></tt> for any built-in command, or the
|
||
|
|
completed pathname of any executable file.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<tt><font size=+1>~</font></tt> <i>subject pattern ...<br>
|
||
|
|
</i>
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
The <i>subject</i> is matched against each <i>pattern</i> in sequence. If it
|
||
|
|
matches any pattern, <tt><font size=+1>$status</font></tt> is set to zero. Otherwise, <tt><font size=+1>$status</font></tt>
|
||
|
|
is set to one. Patterns are the same as for file name matching,
|
||
|
|
except that <tt><font size=+1>/</font></tt> and the first character of <tt><font size=+1>.</font></tt> and <tt><font size=+1>..</font></tt> need not be
|
||
|
|
matched explicitly. The <i>patterns</i> are not subjected to
|
||
|
|
file name matching before the <tt><font size=+1>~</font></tt> command is executed, so they need
|
||
|
|
not be enclosed in quotation marks.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<p><font size=+1><b>Environment </b></font><br>
|
||
|
|
The <i>environment</i> is a list of strings made available to executing
|
||
|
|
binaries by the kernel. <i>Rc</i> creates an environment entry for each
|
||
|
|
variable whose value is non-empty, and for each function. The
|
||
|
|
string for a variable entry has the variable’s name followed by
|
||
|
|
<tt><font size=+1>=</font></tt> and its value. If the value has more than one component,
|
||
|
|
these are separated by SOH (001) characters. The string for a
|
||
|
|
function is just the <i>rc</i> input that defines the function. The name
|
||
|
|
of a function in the environment is the function name preceded
|
||
|
|
by <tt><font size=+1>fn#</font></tt>.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
When <i>rc</i> starts executing it reads variable and function definitions
|
||
|
|
from its environment.<br>
|
||
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|
<p><font size=+1><b>Special Variables </b></font><br>
|
||
|
|
The following variables are set or used by <i>rc</i>.<br>
|
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|
<tt><font size=+1>$*</font></tt> Set to <i>rc</i>’s argument list during initialization. Whenever a
|
||
|
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<tt><font size=+1>.</font></tt> command or a function is executed, the current value is saved
|
||
|
|
and <tt><font size=+1>$*</font></tt> receives the new argument list. The saved value is restored
|
||
|
|
on completion of the <tt><font size=+1>.</font></tt> or function.<br>
|
||
|
|
<tt><font size=+1>$apid</font></tt> Whenever a process is started asynchronously with <tt><font size=+1>&</font></tt>, <tt><font size=+1>$apid</font></tt>
|
||
|
|
is set to its process id.<br>
|
||
|
|
<tt><font size=+1>$home</font></tt> The default directory for <tt><font size=+1>cd</font></tt>.<br>
|
||
|
|
<tt><font size=+1>$ifs</font></tt> The input field separators used in backquote substitutions.
|
||
|
|
If <tt><font size=+1>$ifs</font></tt> is not set in <i>rc</i>’s environment, it is initialized to blank,
|
||
|
|
tab and newline.<br>
|
||
|
|
<tt><font size=+1>$path</font></tt> The search path used to find commands and input files for
|
||
|
|
the <tt><font size=+1>.</font></tt> command. If not set in the environment, it is initialized
|
||
|
|
by parsing the <tt><font size=+1>$PATH</font></tt> variable (as in <a href="../man1/sh.html"><i>sh</i>(1)</a>) or by <tt><font size=+1>path=(. /bin)</font></tt>.
|
||
|
|
The variables <tt><font size=+1>$path</font></tt> and <tt><font size=+1>$PATH</font></tt> are maintained together: changes
|
||
|
|
to one will be reflected in the other.
|
||
|
|
<tt><font size=+1>$pid</font></tt> Set during initialization to <i>rc</i>’s process id.<br>
|
||
|
|
<tt><font size=+1>$prompt</font></tt> When <i>rc</i> is run interactively, the first component of <tt><font size=+1>$prompt</font></tt>
|
||
|
|
is printed before reading each command. The second component is
|
||
|
|
printed whenever a newline is typed and more lines are required
|
||
|
|
to complete the command. If not set in the environment, it is
|
||
|
|
initialized by <tt><font size=+1>prompt=('% ' ' ')</font></tt>.
|
||
|
|
<tt><font size=+1>$status</font></tt> Set to the wait message of the last-executed program. (unless
|
||
|
|
started with <tt><font size=+1>&). !</font></tt> and <tt><font size=+1>~</font></tt> also change <tt><font size=+1>$status</font></tt>. Its value is used
|
||
|
|
to control execution in <tt><font size=+1>&&</font></tt>, <tt><font size=+1>||</font></tt>, <tt><font size=+1>if</font></tt> and <tt><font size=+1>while</font></tt> commands. When <i>rc</i> exits
|
||
|
|
at end-of-file of its input or on executing an <tt><font size=+1>exit</font></tt> command with
|
||
|
|
no argument, <tt><font size=+1>$status</font></tt> is its
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
exit status.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<p><font size=+1><b>Invocation </b></font><br>
|
||
|
|
If <i>rc</i> is started with no arguments it reads commands from standard
|
||
|
|
input. Otherwise its first non-flag argument is the name of a
|
||
|
|
file from which to read commands (but see <tt><font size=+1>−c</font></tt> below). Subsequent
|
||
|
|
arguments become the initial value of <tt><font size=+1>$*</font></tt>. <i>Rc</i> accepts the following
|
||
|
|
command-line flags.<br>
|
||
|
|
<tt><font size=+1>−c</font></tt> <i>string</i> Commands are read from <i>string</i>.<br>
|
||
|
|
<tt><font size=+1>−s</font></tt> Print out exit status after any command where the status is
|
||
|
|
non-null.<br>
|
||
|
|
<tt><font size=+1>−e</font></tt> Exit if <tt><font size=+1>$status</font></tt> is non-null after executing a simple command.<br>
|
||
|
|
<tt><font size=+1>−i</font></tt> If <tt><font size=+1>−i</font></tt> is present, or <i>rc</i> is given no arguments and its standard
|
||
|
|
input is a terminal, it runs interactively. Commands are prompted
|
||
|
|
for using <tt><font size=+1>$prompt</font></tt>.<br>
|
||
|
|
<tt><font size=+1>−I</font></tt> Makes sure <i>rc</i> is not run interactively.<br>
|
||
|
|
<tt><font size=+1>−l</font></tt> If <tt><font size=+1>−l</font></tt> is given or the first character of argument zero is <tt><font size=+1>−</font></tt>,
|
||
|
|
<i>rc</i> reads commands from <tt><font size=+1>$home/lib/profile</font></tt>, if it exists, before
|
||
|
|
reading its normal input.<br>
|
||
|
|
<tt><font size=+1>−p</font></tt> A no-op.<br>
|
||
|
|
<tt><font size=+1>−d</font></tt> A no-op.<br>
|
||
|
|
<tt><font size=+1>−v</font></tt> Echo input on file descriptor 2 as it is read.<br>
|
||
|
|
<tt><font size=+1>−x</font></tt> Print each simple command before executing it.<br>
|
||
|
|
<tt><font size=+1>−r</font></tt> Print debugging information (internal form of commands as they
|
||
|
|
are executed).<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<p><font size=+1><b>SOURCE </b></font><br>
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
<tt><font size=+1>/usr/local/plan9/src/cmd/rc<br>
|
||
|
|
</font></tt>
|
||
|
|
</table>
|
||
|
|
<p><font size=+1><b>SEE ALSO </b></font><br>
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
Tom Duff, “Rc – The Plan 9 Shell”.<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
<p><font size=+1><b>BUGS </b></font><br>
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
There should be a way to match patterns against whole lists rather
|
||
|
|
than just single strings.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
Using <tt><font size=+1>~</font></tt> to check the value of <tt><font size=+1>$status</font></tt> changes <tt><font size=+1>$status</font></tt>.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
Functions that use here documents don’t work.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
Free carets don’t get inserted next to keywords.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
The <tt><font size=+1><{</font></tt><i>command</i><tt><font size=+1>}</font></tt> syntax depends on the underlying operating system
|
||
|
|
providing a file descriptor device tree at <tt><font size=+1>/dev/fd</font></tt>.
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
|
||
|
|
By default, FreeBSD 5 does not provide file descriptors greater
|
||
|
|
than 2 in <tt><font size=+1>/dev/fd</font></tt>. To fix this, add<br>
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
||
|
|
|
||
|
|
<tt><font size=+1>/fdescfs /dev/fd fdescfs rw 0 0<br>
|
||
|
|
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
||
|
|
</font></tt>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
to <tt><font size=+1>/etc/fstab</font></tt>, and then <tt><font size=+1>mount /dev/fd</font></tt>. (Adding the line to <tt><font size=+1>fstab</font></tt>
|
||
|
|
ensures causes FreeBSD to mount the file system automatically
|
||
|
|
at boot time.)<br>
|
||
|
|
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<td width=20>
|
||
|
|
<tr height=20><td>
|
||
|
|
</table>
|
||
|
|
<!-- TRAILER -->
|
||
|
|
<table border=0 cellpadding=0 cellspacing=0 width=100%>
|
||
|
|
<tr height=15><td width=10><td><td width=10>
|
||
|
|
<tr><td><td>
|
||
|
|
<center>
|
||
|
|
<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
|
||
|
|
</center>
|
||
|
|
</table>
|
||
|
|
<!-- TRAILER -->
|
||
|
|
</body></html>
|