150 lines
3 KiB
Groff
150 lines
3 KiB
Groff
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.\" $Id: lua.man,v 1.14 2020/05/21 19:31:21 lhf Exp $
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.TH LUA 1 "$Date: 2020/05/21 19:31:21 $"
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.SH NAME
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lua \- Lua interpreter
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.SH SYNOPSIS
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.B lua
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[
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.I options
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]
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[
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.I script
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[
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.I args
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]
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]
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.SH DESCRIPTION
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.B lua
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is the standalone Lua interpreter.
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It loads and executes Lua programs,
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either in textual source form or
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in precompiled binary form.
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(Precompiled binaries are output by
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.BR luac ,
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the Lua compiler.)
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.B lua
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can be used as a batch interpreter and also interactively.
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.LP
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After handling the
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.IR options ,
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the Lua program in file
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.I script
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is loaded and executed.
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The
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.I args
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are available to
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.I script
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as strings in a global table named
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.B arg
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and also as arguments to its main function.
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When called without arguments,
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.B lua
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behaves as
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.B "lua \-v \-i"
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if the standard input is a terminal,
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and as
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.B "lua \-"
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otherwise.
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.LP
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In interactive mode,
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.B lua
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prompts the user,
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reads lines from the standard input,
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and executes them as they are read.
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If the line contains an expression,
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then the line is evaluated and the result is printed.
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If a line does not contain a complete statement,
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then a secondary prompt is displayed and
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lines are read until a complete statement is formed or
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a syntax error is found.
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.LP
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Before handling command line options and scripts,
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.B lua
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checks the contents of the environment variables
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.B LUA_INIT_5_4
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and
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.BR LUA_INIT ,
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in that order.
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If the contents are of the form
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.RI '@ filename ',
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then
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.I filename
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is executed.
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Otherwise, the contents are assumed to be a Lua statement and is executed.
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When
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.B LUA_INIT_5_4
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is defined,
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.B LUA_INIT
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is ignored.
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.SH OPTIONS
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.TP
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.BI \-e " stat"
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execute statement
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.IR stat .
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.TP
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.B \-i
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enter interactive mode after executing
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.IR script .
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.TP
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.BI \-l " name"
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require library
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.I name
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into global
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.IR name .
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.TP
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.B \-v
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show version information.
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.TP
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.B \-E
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ignore environment variables.
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.TP
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.B \-W
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turn warnings on.
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.TP
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.B \-\-
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stop handling options.
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.TP
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.B \-
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stop handling options and execute the standard input as a file.
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.SH ENVIRONMENT VARIABLES
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The following environment variables affect the execution of
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.BR lua .
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When defined,
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the version-specific variants take priority
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and the version-neutral variants are ignored.
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.TP
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.B LUA_INIT, LUA_INIT_5_4
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Code to be executed before command line options and scripts.
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.TP
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.B LUA_PATH, LUA_PATH_5_4
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Initial value of package.cpath,
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the path used by require to search for Lua loaders.
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.TP
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.B LUA_CPATH, LUA_CPATH_5_4
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Initial value of package.cpath,
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the path used by require to search for C loaders.
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.SH EXIT STATUS
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If a script calls os.exit,
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then
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.B lua
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exits with the given exit status.
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Otherwise,
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.B lua
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exits
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with EXIT_SUCCESS (0 on POSIX systems) if there were no errors
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and
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with EXIT_FAILURE (1 on POSIX systems) if there were errors.
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Errors raised in interactive mode do not cause exits.
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.SH DIAGNOSTICS
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Error messages should be self explanatory.
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.SH "SEE ALSO"
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.BR luac (1)
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.br
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The documentation at lua.org,
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especially section 7 of the reference manual.
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.SH AUTHORS
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R. Ierusalimschy,
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L. H. de Figueiredo,
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W. Celes
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.\" EOF
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