Type Function Object File Library io.* Return value Number Revision Release 2021.3642 Keywords seek, files See also io.open()
Sets and gets the file position, measured from the beginning of the file, to the position given by offset plus a base.
The function can be used to get the current file position (
"set" the file position to the beginning, end, or any position between.
File:seek( [mode] [, offset] )
String. Can be one of the following values:
"set"— base is position 0 (beginning of the file)
"cur"— base is current position (default)
"end"— base is end of file
The default value for mode is
"cur", and for offset is
0. Therefore, the call
File:seek() returns the current file position without changing it. The call
File:seek("set") sets the position to the beginning of the file and returns
0. The call
File:seek("end") sets the position to the end of the file, and returns its size.
Number. Specifies the position for the
"set" mode. The number is
0 based (which is the beginning of the file).
local fh = io.tmpfile() fh:write( "My temporary file data" ) fh:flush() -- Ensure data written to file print( "file position: ", fh:seek() ) -- Show current position fh:seek( "set", 0 ) -- Reset file position to beginning local content = fh:read( "*a" ) -- Read all the file print( "File content: " .. content ) print( "file position: ", fh:seek("end") ) -- Show the end position of file