--- name: "lua50" section: "1" platform: "linux" package: "lua50" version: "5.0.3-8.1" release: "Debian 11 (Bullseye)" platforms: ["linux"] url: "https://new.carta.tech/lua50" --- # lua50(1) Lua interpreter ## NAME lua - Lua interpreter ## SYNOPSIS **lua** \[ *options* \] \[ *script* \[ *args* \] \] ## DESCRIPTION **lua** is the stand-alone Lua interpreter. It loads and executes Lua programs, 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 contain 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 standard 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 statement is to force a syntax error: adding a **\`;'** in the middle of a statement 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 with **\_PROMPT**=´lua: ´**,** for example. (Note the need for quotes, because the string contains a space.) The default prompts are \`\`\> '' and \`\`\>\> ''. ## OPTIONS - **-** 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** *file* call **require(***file***)** before executing *script.* Typically used to load libraries (hence the letter *l*). - **-v** show version information. - **-P** suppress the creation of a standard LUA\_PATH variable. Use this if you need to run scripts which conflict with system-installed libraries. ## SEE ALSO [**luac**(1)](/luac/1.md)\ http://www.lua.org/ ## DIAGNOSTICS Error messages should be self explanatory. ## AUTHORS R. Ierusalimschy, L. H. de Figueiredo, and W. Celes **\** Debian modifications to the manpage by Daniel Silverstone **\**