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NAME | DESCRIPTION | SEE ALSO | COLOPHON |
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pathname(7) Miscellaneous Information Manual pathname(7)
pathname, filename - how pathnames are encoded and interpreted
Some system calls allow you to pass a pathname as a parameter.
When writing code that deals with pathnames, there are kernel-
space requirements that you must comply with, and user-space
requirements that you should comply with.
The kernel stores pathnames as C strings, that is, sequences of
non-null bytes terminated by a null byte. There are a few general
rules that apply to all pathnames:
• The last byte in the sequence needs to be a null byte.
• Any other bytes in the sequence need to be non-null bytes.
• A 0x2F byte ('/') is always interpreted as a directory
separator, and cannot be part of a filename.
• A pathname can be at most PATH_MAX bytes long (see
limits.h(0p)). A pathname that's longer than PATH_MAX bytes
can be split into multiple smaller pathnames and opened
piecewise using openat(2).
• A filename can be at most a certain number of bytes long. The
number is filesystem-specific (see _PC_NAME_MAX in
fpathconf(3)). For maximum portability, programs should be
able to handle filenames that are as long as the relevant
filesystems will allow. For maximum portability, programs and
users should limit the length of their own pathnames to
NAME_MAX bytes (see limits.h(0p)).
Some filesystems or APIs may apply further restrictions, such as
requiring shorter filenames, or restricting the allowed bytes in a
filename.
For maximum interoperability, programs and users should also limit
the characters that they use for their own pathnames to characters
in the POSIX Portable Filename Character Set
⟨https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap03.html#tag_03_265⟩.
limits.h(0p), open(2), fpathconf(3), path_resolution(7), mount(8)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 pathname(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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