Previously, only files smaller than 2 gigabytes were supported in POSIX. This was because the data within a file was addressed with a variable of the data type integer (signed). This could only address a maximum of 231–1 bytes, i.e. 2 gigabytes.
This limit caused problems with different applications, for instance, with print files with memory-intensive graphics. Consequently, more users called for the maximum file size to be increased. This was also supported by the standardization authorities and led to a new standard being defined for large files.
Standard for large files
The central point of this standard is that a “long long” variable is used to address data within a file. This data type consists of an integer pair, which enables an address to be 263–1 bytes long, including the sign.
This new class of files should of course be as compatible as possible with the existing ones, so that existing programs can also work with large files without any great difficulty. That is to say, it should be possible to process the large files where possible with the same interfaces as previous files, at least in terms of syntax and semantics.