The standard Lua libraries provide useful functions and are implemented as separate C modules. Besides the basic and package libraries they all provides its functions as fields in a global table or as methods of its objects. The host program can load them all with luaL_openlibs or specific ones with luaL_requiref.
collectgarbage ([opt [, arg]])
Function to control the garbage collector. Opt is a string that is used to select what to tell the garbage collector to do.
error (message [, level])
A global variable that holds the global environment.
next (table [, index])
setmetatable (table, metatable)
tonumber (e [, base])
Convert v to a string. If v has a metatable __tostring field it is called and used to get the result.
Returns the type of v as a string.
string - String Manipulation
This library have all it's functions inside the table string. It is also set as a metatable for values of the type string so it is possible to use string in a object-oriented style. Strings are index with the first character at position 1. Negatived indexes are used to index backwards from the end of the string.
table - Table Manipulation
math - Mathematical Functions
io - Input and output
os - Operating system