File systems for UNIX-like operating systems also store the file name as a single string, with "." as just another character in the file name. A file with more than one suffix is sometimes said to have more than one extension, although terminology varies in this regard, and most authors define extension in a way that does not allow more than one in the same file name. More than one extension usually represents nested transformations, such as files.tar.gz (the .tar indicates that the file is a tar archive of one or more files, and the .gz indicates that the tar archive file is compressed with gzip). Programs transforming or creating files may add the appropriate extension to names inferred from input file names (unless explicitly given an output file name), but programs reading files usually ignore the information; it is mostly intended for the human user. It is more common, especially in binary files, for the file to contain internal or external metadata describing its contents. This model generally requires the full filename to be provided in commands, whereas the metadata approach often allows the extension to be omitted.
File systems for UNIX-like operating systems also store the file name as a single string with "" as just another character in the file name A file with more than one suffix is sometimes said to have more than one extension although terminology varies in this regard and most authors define extension in a way that does not allow more than one in the same file name More than one extension usually represents nested transformations such as filestargz (the tar indicates that the file is a tar archive of one or more files and the gz indicates that the tar archive file is compressed with gzip) Programs transforming or creating files may add the appropriate extension to names inferred from input file names (unless explicitly given an output file name) but programs reading files usually ignore the information; it is mostly intended for the human user It is more common especially in binary files for the file to contain internal or external metadata describing its contents This model generally requires the full filename to be provided in commands whereas the metadata approach often allows the extension to be omitted