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  1. <!-- $Id: lua.man,v 1.11 2006/01/06 16:03:34 lhf Exp $ -->
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  3. <HEAD>
  4. <TITLE>LUA man page</TITLE>
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  9.  
  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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