lua/doc/lua.html

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  10 <H2>NAME</H2>
  11 lua - Lua interpreter
  12 <H2>SYNOPSIS</H2>
  13 <B>lua</B>
  14 [
  15 <I>options</I>
  16 ]
  17 [
  18 <I>script</I>
  19 [
  20 <I>args</I>
  21 ]
  22 ]
  23 <H2>DESCRIPTION</H2>
  24 <B>lua</B>
  25 is the stand-alone Lua interpreter.
  26 It loads and executes Lua programs,
  27 either in textual source form or
  28 in precompiled binary form.
  29 (Precompiled binaries are output by
  30 <B>luac</B>,
  31 the Lua compiler.)
  32 <B>lua</B>
  33 can be used as a batch interpreter and also interactively.
  34 <P>
  35 The given
  36 <I>options</I>
  37 (see below)
  38 are executed and then
  39 the Lua program in file
  40 <I>script</I>
  41 is loaded and executed.
  42 The given
  43 <I>args</I>
  44 are available to
  45 <I>script</I>
  46 as strings in a global table named
  47 <B>arg</B>.
  48 If these arguments contain spaces or other characters special to the shell,
  49 then they should be quoted
  50 (but note that the quotes will be removed by the shell).
  51 The arguments in
  52 <B>arg</B>
  53 start at 0,
  54 which contains the string
  55 '<I>script</I>'.
  56 The index of the last argument is stored in
  57 <B>arg.n</B>.
  58 The arguments given in the command line before
  59 <I>script</I>,
  60 including the name of the interpreter,
  61 are available in negative indices in
  62 <B>arg</B>.
  63 <P>
  64 At the very start,
  65 before even handling the command line,
  66 <B>lua</B>
  67 executes the contents of the environment variable
  68 <B>LUA_INIT</B>,
  69 if it is defined.
  70 If the value of
  71 <B>LUA_INIT</B>
  72 is of the form
  73 '@<I>filename</I>',
  74 then
  75 <I>filename</I>
  76 is executed.
  77 Otherwise, the string is assumed to be a Lua statement and is executed.
  78 <P>
  79 Options start with
  80 <B>'-'</B>
  81 and are described below.
  82 You can use
  83 <B>'--'</B>
  84 to signal the end of options.
  85 <P>
  86 If no arguments are given,
  87 then
  88 <B>"-v -i"</B>
  89 is assumed when the standard input is a terminal;
  90 otherwise,
  91 <B>"-"</B>
  92 is assumed.
  93 <P>
  94 In interactive mode,
  95 <B>lua</B>
  96 prompts the user,
  97 reads lines from the standard input,
  98 and executes them as they are read.
  99 If a line does not contain a complete statement,
 100 then a secondary prompt is displayed and
 101 lines are read until a complete statement is formed or
 102 a syntax error is found.
 103 So, one way to interrupt the reading of an incomplete statement is
 104 to force a syntax error:
 105 adding a
 106 <B>';'</B>
 107 in the middle of a statement is a sure way of forcing a syntax error
 108 (except inside multiline strings and comments; these must be closed explicitly).
 109 If a line starts with
 110 <B>'='</B>,
 111 then
 112 <B>lua</B>
 113 displays the values of all the expressions in the remainder of the
 114 line. The expressions must be separated by commas.
 115 The primary prompt is the value of the global variable
 116 <B>_PROMPT</B>,
 117 if this value is a string;
 118 otherwise, the default prompt is used.
 119 Similarly, the secondary prompt is the value of the global variable
 120 <B>_PROMPT2</B>.
 121 So,
 122 to change the prompts,
 123 set the corresponding variable to a string of your choice.
 124 You can do that after calling the interpreter
 125 or on the command line
 126 (but in this case you have to be careful with quotes
 127 if the prompt string contains a space; otherwise you may confuse the shell.)
 128 The default prompts are "&gt; " and "&gt;&gt; ".
 129 <H2>OPTIONS</H2>
 130 <P>
 131 <B>-</B>
 132 load and execute the standard input as a file,
 133 that is,
 134 not interactively,
 135 even when the standard input is a terminal.
 136 <P>
 137 <B>-e </B><I>stat</I>
 138 execute statement
 139 <I>stat</I>.
 140 You need to quote
 141 <I>stat </I>
 142 if it contains spaces, quotes,
 143 or other characters special to the shell.
 144 <P>
 145 <B>-i</B>
 146 enter interactive mode after
 147 <I>script</I>
 148 is executed.
 149 <P>
 150 <B>-l </B><I>name</I>
 151 call
 152 <B>require</B>('<I>name</I>')
 153 before executing
 154 <I>script</I>.
 155 Typically used to load libraries.
 156 <P>
 157 <B>-v</B>
 158 show version information.
 159 <H2>SEE ALSO</H2>
 160 <B>luac</B>(1)
 161 <BR>
 162 <A HREF="http://www.lua.org/">http://www.lua.org/</A>
 163 <H2>DIAGNOSTICS</H2>
 164 Error messages should be self explanatory.
 165 <H2>AUTHORS</H2>
 166 R. Ierusalimschy,
 167 L. H. de Figueiredo,
 168 and
 169 W. Celes
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