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| <title>rc(1) - Plan 9 from User Space</title> |
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| <tr><td width=20><td> |
| <tr><td width=20><td><b>RC(1)</b><td align=right><b>RC(1)</b> |
| <tr><td width=20><td colspan=2> |
| <br> |
| <p><font size=+1><b>NAME </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| rc, cd, eval, exec, exit, flag, rfork, shift, wait, whatis, ., |
| ~ – command language<br> |
| |
| </table> |
| <p><font size=+1><b>SYNOPSIS </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <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> |
| |
| </table> |
| <p><font size=+1><b>DESCRIPTION </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <i>Rc</i> is the Plan 9 shell. It executes command lines read from a |
| terminal or a file or, with the <tt><font size=+1>−c</font></tt> flag, from <i>rc’s</i> argument list.<br> |
| <p><font size=+1><b>Command Lines </b></font><br> |
| A command line is a sequence of commands, separated by ampersands |
| or semicolons (<tt><font size=+1>&</font></tt> or <tt><font size=+1>;</font></tt>), terminated by a newline. The commands are |
| executed in sequence from left to right. <i>Rc</i> does not wait for |
| a command followed by <tt><font size=+1>&</font></tt> to finish executing before starting the |
| following command. Whenever a command |
| followed by <tt><font size=+1>&</font></tt> is executed, its process id is assigned to the <i>rc</i> |
| variable <tt><font size=+1>$apid</font></tt>. Whenever a command <i>not</i> followed by <tt><font size=+1>&</font></tt> exits or is |
| terminated, the <i>rc</i> variable <tt><font size=+1>$status</font></tt> gets the process’s wait message |
| (see <a href="../man3/wait.html"><i>wait</i>(3)</a>); it will be the null string if the command was successful. |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| A long command line may be continued on subsequent lines by typing |
| a backslash (<tt><font size=+1>\</font></tt>) followed by a newline. This sequence is treated |
| as though it were a blank. Backslash is not otherwise a special |
| character. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| A number-sign (<tt><font size=+1>#</font></tt>) and any following characters up to (but not |
| including) the next newline are ignored, except in quotation marks.<br> |
| <p><font size=+1><b>Simple Commands </b></font><br> |
| A simple command is a sequence of arguments interspersed with |
| I/O redirections. If the first argument is the name of an <i>rc</i> function |
| or of one of <i>rc’s</i> built-in commands, it is executed by <i>rc</i>. Otherwise |
| if the name starts with a slash (<tt><font size=+1>/</font></tt>), it must be the path name |
| of the program to be executed. Names containing no |
| initial slash are searched for in a list of directory names stored |
| in <tt><font size=+1>$path</font></tt>. The first executable file of the given name found in |
| a directory in <tt><font size=+1>$path</font></tt> is the program to be executed. To be executable, |
| the user must have execute permission (see <a href="../man3/stat.html"><i>stat</i>(3)</a>) and the file |
| must be either an executable binary for the current |
| machine’s CPU type, or a shell script. Shell scripts begin with |
| a line containing the full path name of a shell (usually <tt><font size=+1>/bin/rc</font></tt>), |
| prefixed by <tt><font size=+1>#!</font></tt>. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| The first word of a simple command cannot be a keyword unless |
| it is quoted or otherwise disguised. The keywords are<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>for in while if not switch fn ~ ! @<br> |
| </font></tt> |
| </table> |
| <p><font size=+1><b>Arguments and Variables </b></font><br> |
| A number of constructions may be used where <i>rc’s</i> syntax requires |
| an argument to appear. In many cases a construction’s value will |
| be a list of arguments rather than a single string. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| The simplest kind of argument is the unquoted word: a sequence |
| of one or more characters none of which is a blank, tab, newline, |
| or any of the following:<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1># ; & | ^ $ = ` ' { } ( ) < ><br> |
| </font></tt> |
| </table> |
| An unquoted word that contains any of the characters <tt><font size=+1>* ? [</font></tt> is |
| a pattern for matching against file names. The character <tt><font size=+1>*</font></tt> matches |
| any sequence of characters, <tt><font size=+1>?</font></tt> matches any single character, and |
| <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 |
| of <i>class</i> is <tt><font size=+1>~</font></tt>, the class is complemented. The <i>class</i> may |
| also contain pairs of characters separated by <tt><font size=+1>−</font></tt>, standing for |
| all characters lexically between the two. The character <tt><font size=+1>/</font></tt> must |
| appear explicitly in a pattern, as must the first character of |
| the path name components <tt><font size=+1>.</font></tt> and <tt><font size=+1>..</font></tt>. A pattern is replaced by a |
| list of arguments, one for each path name matched, except that |
| a |
| pattern matching no names is not replaced by the empty list, but |
| rather stands for itself. Pattern matching is done after all other |
| operations. Thus,<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>x=/tmp echo $x^/*.c<br> |
| </font></tt> |
| </table> |
| matches <tt><font size=+1>/tmp/*.c</font></tt>, rather than matching <tt><font size=+1>/*.c</font></tt> and then prefixing |
| <tt><font size=+1>/tmp</font></tt>. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| A quoted word is a sequence of characters surrounded by single |
| quotes (<tt><font size=+1>'</font></tt>). A single quote is represented in a quoted word by |
| a pair of quotes (<tt><font size=+1>''</font></tt>). |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| Each of the following is an argument.<br> |
| <tt><font size=+1>(</font></tt><i>arguments</i><tt><font size=+1>)<br> |
| </font></tt> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| The value of a sequence of arguments enclosed in parentheses is |
| a list comprising the members of each element of the sequence. |
| Argument lists have no recursive structure, although their syntax |
| may suggest it. The following are entirely equivalent:<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>echo hi there everybody<br> |
| ((echo) (hi there) everybody)<br> |
| </font></tt> |
| </table> |
| |
| </table> |
| <tt><font size=+1>$</font></tt><i>argument<br> |
| </i><tt><font size=+1>$</font></tt><i>argument</i><tt><font size=+1>(</font></tt><i>subscript</i><tt><font size=+1>)<br> |
| </font></tt> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| The <i>argument</i> after the <tt><font size=+1>$</font></tt> is the name of a variable whose value |
| is substituted. Multiple levels of indirection are possible, but |
| of questionable utility. Variable values are lists of strings. |
| If <i>argument</i> is a number <i>n</i>, the value is the <i>n</i>th element of <tt><font size=+1>$*</font></tt>, |
| unless <tt><font size=+1>$*</font></tt> doesn’t have <i>n</i> elements, in which case the value is |
| empty. If <i>argument</i> is followed by a parenthesized list of subscripts, |
| the value substituted is a list composed of the requested elements |
| (origin 1). The parenthesis must follow the variable name with |
| no spaces. Assignments to variables are described below.<br> |
| |
| </table> |
| <tt><font size=+1>$#</font></tt><i>argument<br> |
| </i> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| The value is the number of elements in the named variable. A variable |
| never assigned a value has zero elements.<br> |
| |
| </table> |
| $"<i>argument<br> |
| </i> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| The value is a single string containing the components of the |
| named variable separated by spaces. A variable with zero elements |
| yields the empty string.<br> |
| |
| </table> |
| <tt><font size=+1>`{</font></tt><i>command</i><tt><font size=+1>}<br> |
| </font></tt> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <i>rc</i> executes the <i>command</i> and reads its standard output, splitting |
| it into a list of arguments, using characters in <tt><font size=+1>$ifs</font></tt> as separators. |
| If <tt><font size=+1>$ifs</font></tt> is not otherwise set, its value is <tt><font size=+1>' \t\n'</font></tt>.<br> |
| |
| </table> |
| <tt><font size=+1><{</font></tt><i>command</i><tt><font size=+1>}<br> |
| >{</font></tt><i>command</i><tt><font size=+1>}<br> |
| </font></tt> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| The <i>command</i> is executed asynchronously with its standard output |
| or standard input connected to a pipe. The value of the argument |
| is the name of a file referring to the other end of the pipe. |
| This allows the construction of non-linear pipelines. For example, |
| the following runs two commands <tt><font size=+1>old</font></tt> and <tt><font size=+1>new |
| </font></tt>and uses <tt><font size=+1>cmp</font></tt> to compare their outputs<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>cmp <{old} <{new}<br> |
| </font></tt> |
| </table> |
| |
| </table> |
| <i>argument</i><tt><font size=+1>^</font></tt><i>argument<br> |
| </i> |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| The <tt><font size=+1>^</font></tt> operator concatenates its two operands. If the two operands |
| have the same number of components, they are concatenated pairwise. |
| If not, then one operand must have one component, and the other |
| must be non-empty, and concatenation is distributive.<br> |
| |
| </table> |
| <p><font size=+1><b>Free Carets </b></font><br> |
| In most circumstances, <i>rc</i> will insert the <tt><font size=+1>^</font></tt> operator automatically |
| between words that are not separated by white space. Whenever |
| one of <tt><font size=+1>$ ' `</font></tt> follows a quoted or unquoted word or an unquoted |
| word follows a quoted word with no intervening blanks or tabs, |
| a <tt><font size=+1>^</font></tt> is inserted between the two. If an unquoted word |
| immediately follows a <tt><font size=+1>$</font></tt> and contains a character other than an |
| alphanumeric, underscore, or <tt><font size=+1>*</font></tt>, a <tt><font size=+1>^</font></tt> is inserted before the first |
| such character. Thus<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>cc −$flags $stem.c |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| </font></tt> |
| |
| </table> |
| is equivalent to<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>cc −^$flags $stem^.c<br> |
| </font></tt> |
| </table> |
| <p><font size=+1><b>I/O Redirections </b></font><br> |
| The sequence <tt><font size=+1>></font></tt><i>file</i> redirects the standard output file (file descriptor |
| 1, normally the terminal) to the named <i>file</i>; <tt><font size=+1>>></font></tt><i>file</i> appends standard |
| output to the file. The standard input file (file descriptor 0, |
| also normally the terminal) may be redirected from a file by the |
| sequence <tt><font size=+1><</font></tt><i>file</i>, or from an inline ‘here document’ by the |
| sequence <tt><font size=+1><<</font></tt><i>eof-marker</i>. The contents of a here document are lines |
| of text taken from the command input stream up to a line containing |
| nothing but the <i>eof-marker</i>, which may be either a quoted or unquoted |
| word. If <i>eof-marker</i> is unquoted, variable names of the form <tt><font size=+1>$</font></tt><i>word</i> |
| have their values substituted from <i>rc’s |
| </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 |
| deleted. If <i>eof-marker</i> is quoted, no substitution occurs. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| Redirections may be applied to a file-descriptor other than standard |
| input or output by qualifying the redirection operator with a |
| number in square brackets. For example, the diagnostic output |
| (file descriptor 2) may be redirected by writing <tt><font size=+1>cc junk.c >[2]junk</font></tt>. |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| A file descriptor may be redirected to an already open descriptor |
| 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 |
| file descriptor and <i>fd0</i> becomes a new copy (in the sense of <a href="../man3/dup.html"><i>dup</i>(3)</a>) |
| 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>. |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| Redirections are executed from left to right. Therefore, <tt><font size=+1>cc junk.c |
| >/dev/null >[2=1]</font></tt> and <tt><font size=+1>cc junk.c >[2=1] >/dev/null</font></tt> have different effects: |
| the first puts standard output in <tt><font size=+1>/dev/null</font></tt> and then puts diagnostic |
| output in the same place, where the second directs diagnostic |
| output to the |
| terminal and sends standard output to <tt><font size=+1>/dev/null</font></tt>.<br> |
| <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>$status</font></tt> |
| is set to one. Patterns are the same as for file name matching, |
| except that <tt><font size=+1>/</font></tt> and the first character of <tt><font size=+1>.</font></tt> and <tt><font size=+1>..</font></tt> need not be |
| matched explicitly. The <i>patterns</i> are not subjected to |
| file name matching before the <tt><font size=+1>~</font></tt> command is executed, so they need |
| not be enclosed in quotation marks.<br> |
| |
| </table> |
| <p><font size=+1><b>Environment </b></font><br> |
| The <i>environment</i> is a list of strings made available to executing |
| binaries by the kernel. <i>Rc</i> creates an environment entry for each |
| variable whose value is non-empty, and for each function. The |
| string for a variable entry has the variable’s name followed by |
| <tt><font size=+1>=</font></tt> and its value. If the value has more than one component, |
| these are separated by SOH (001) characters. The string for a |
| function is just the <i>rc</i> input that defines the function. The name |
| of a function in the environment is the function name preceded |
| by <tt><font size=+1>fn#</font></tt>. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| When <i>rc</i> starts executing it reads variable and function definitions |
| from its environment.<br> |
| <p><font size=+1><b>Special Variables </b></font><br> |
| The following variables are set or used by <i>rc</i>.<br> |
| <tt><font size=+1>$*</font></tt> Set to <i>rc</i>’s argument list during initialization. Whenever a |
| <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> |
