file:read()

file:read (···)

Reads the file file, according to the given formats, which specify what to read. For each format, the function returns a string or a number with the characters read, or nil if it cannot read data with the specified format. (In this latter case, the function does not read subsequent formats.) When called without formats, it uses a default format that reads the next line (see below).

The available formats are

• "n": reads a numeral and returns it as a float or an integer, following the lexical conventions of Lua. (The numeral may have leading spaces and a sign.) This format always reads the longest input sequence that is a valid prefix for a numeral; if that prefix does not form a valid numeral (e.g., an empty string, "0x", or "3.4e-"), it is discarded and the function returns nil.
• "a": reads the whole file, starting at the current position. On end of file, it returns the empty string.
• "l": reads the next line skipping the end of line, returning nil on end of file. This is the default format.
• "L": reads the next line keeping the end-of-line character (if present), returning nil on end of file.
• number: reads a string with up to this number of bytes, returning nil on end of file. If number is zero, it reads nothing and returns an empty string, or nil on end of file.

The formats "l" and "L" should be used only for text files.