lua5.1 Man page

LUA(1) General Commands Manual LUA(1)


lua – Lua interpreter


lua [ options ] [ script [ args ] ]


lua is the stand-alone Lua interpreter. It loads and executes Lua pro‐
grams, either in textual source form or in precompiled binary form.
(Precompiled binaries are output by luac, the Lua compiler.) lua can
be used as a batch interpreter and also interactively.

The given options (see below) are executed and then the Lua program in
file script is loaded and executed. The given args are available to
script as strings in a global table named arg. If these arguments con‐
tain spaces or other characters special to the shell, then they should
be quoted (but note that the quotes will be removed by the shell). The
arguments in arg start at 0, which contains the string ‘script’. The
index of the last argument is stored in arg.n. The arguments given in
the command line before script, including the name of the interpreter,
are available in negative indices in arg.

At the very start, before even handling the command line, lua executes
the contents of the environment variable LUA_INIT, if it is defined.
If the value of LUA_INIT is of the form ‘@filename’, then filename is
executed. Otherwise, the string is assumed to be a Lua statement and
is executed.

Options start with ‘-‘ and are described below. You can use ‘–‘ to
signal the end of options.

If no arguments are given, then -v -i is assumed when the standard
input is a terminal; otherwise, – is assumed.

In interactive mode, lua prompts the user, reads lines from the stan‐
dard input, and executes them as they are read. If a line does not
contain a complete statement, then a secondary prompt is displayed and
lines are read until a complete statement is formed or a syntax error
is found. So, one way to interrupt the reading of an incomplete state‐
ment is to force a syntax error: adding a ‘;’ in the middle of a state‐
ment is a sure way of forcing a syntax error (except inside multiline
strings and comments; these must be closed explicitly). If a line
starts with ‘=’, then lua displays the values of all the expressions in
the remainder of the line. The expressions must be separated by commas.
The primary prompt is the value of the global variable _PROMPT, if this
value is a string; otherwise, the default prompt is used. Similarly,
the secondary prompt is the value of the global variable _PROMPT2. So,
to change the prompts, set the corresponding variable to a string of
your choice. You can do that after calling the interpreter or on the
command line (but in this case you have to be careful with quotes if
the prompt string contains a space; otherwise you may confuse the
shell.) The default prompts are “> ” and “>> “.


– load and execute the standard input as a file, that is, not
interactively, even when the standard input is a terminal.

-e stat
execute statement stat. You need to quote stat if it contains
spaces, quotes, or other characters special to the shell.

-i enter interactive mode after script is executed.

-l name
call require(‘name’) before executing script. Typically used to
load libraries.

-v show version information.



Error messages should be self explanatory.

R. Ierusalimschy, L. H. de Figueiredo, and W. Celes

$Date: 2006/01/06 16:03:34 $ LUA(1)