Re: Linux file name definition is..

[Greg Wooledge]

On Tue, Sep 19, 2023 at 01:53:38AM +0700, Budi wrote:
> One please state definitvely Linux file name definition is in Posix regex ?.

A file name, rather than a path name?  That means no slashes and no NUL
bytes.  Slashes are used as directory component separators (with a
special exception for a double slash vs. a single slash at the beginning
of an absolute path name), so they are not allowed inside file names.

Literally any other byte is allowed.

Note that a file name is defined as an array of *bytes*, and not
characters.  Thus, character encodings are irrelevant.  Interpretation
of a filename as a string of characters is up to applications to do,
or not to do, as they see fit.

A *path* name is a set of zero or more directory components, plus a
file name, separated by slashes.  An *absolute* path name begins with
a slash.  A *relative* path name does not, and is resolved with respect
to the current working directory.  If an absolute path name begins with
two slash characters, the operating system is allowed to treat it
differently from one beginning with a single slash.  The exact meaning
of that is up to the OS to decide.

The total byte length of a path name may not exceed PATH_MAX, which is
usually defined as 4096 on Linux systems.