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DESCRIPTION top

fpathconf() gets a value for the configuration optionname for the open file descriptorfd.pathconf() gets a value for configuration optionname for the filenamepath. The corresponding macros defined in<unistd.h> are minimum values; if an application wants to take advantage of values which may change, a call tofpathconf() orpathconf() can be made, which may yield more liberal results. Settingname equal to one of the following constants returns the following configuration options:_PC_LINK_MAX The maximum number of links to the file. Iffd orpath refer to a directory, then the value applies to the whole directory. The corresponding macro is_POSIX_LINK_MAX._PC_MAX_CANON The maximum length of a formatted input line, wherefd orpath must refer to a terminal. The corresponding macro is_POSIX_MAX_CANON._PC_MAX_INPUT The maximum length of an input line, wherefd orpath must refer to a terminal. The corresponding macro is_POSIX_MAX_INPUT._PC_NAME_MAX The maximum length of a filename in the directorypath orfd that the process is allowed to create. The corresponding macro is_POSIX_NAME_MAX._PC_PATH_MAX The maximum length of a relative pathname whenpath orfd is the current working directory. The corresponding macro is_POSIX_PATH_MAX._PC_PIPE_BUF The maximum number of bytes that can be written atomically to a pipe of FIFO. Forfpathconf(),fd should refer to a pipe or FIFO. Forfpathconf(),path should refer to a FIFO or a directory; in the latter case, the returned value corresponds to FIFOs created in that directory. The corresponding macro is_POSIX_PIPE_BUF._PC_CHOWN_RESTRICTED This returns a positive value if the use ofchown(2) andfchown(2) for changing a file's user ID is restricted to a process with appropriate privileges, and changing a file's group ID to a value other than the process's effective group ID or one of its supplementary group IDs is restricted to a process with appropriate privileges. According to POSIX.1, this variable shall always be defined with a value other than -1. The corresponding macro is_POSIX_CHOWN_RESTRICTED. Iffd orpath refers to a directory, then the return value applies to all files in that directory._PC_NO_TRUNC This returns nonzero if accessing filenames longer than_POSIX_NAME_MAXgenerates an error. The corresponding macro is_POSIX_NO_TRUNC._PC_VDISABLE This returns nonzero if special character processing can be disabled, wherefd orpath must refer to a terminal.

RETURN VALUE top

The return value of these functions is one of the following: • On error, -1 is returned anderrno is set to indicate the error (for example,EINVAL, indicating thatname is invalid). • Ifname corresponds to a maximum or minimum limit, and that limit is indeterminate, -1 is returned anderrno is not changed. (To distinguish an indeterminate limit from an error, seterrno to zero before the call, and then check whethererrno is nonzero when -1 is returned.) • Ifname corresponds to an option, a positive value is returned if the option is supported, and -1 is returned if the option is not supported. • Otherwise, the current value of the option or limit is returned. This value will not be more restrictive than the corresponding value that was described to the application in<unistd.h> or<limits.h> when the application was compiled.

ERRORS top

EACCES(pathconf()) Search permission is denied for one of the directories in the path prefix ofpath.EBADF(fpathconf())fd is not a valid file descriptor.EINVALname is invalid.EINVALThe implementation does not support an association ofname with the specified file.ELOOP(pathconf()) Too many symbolic links were encountered while resolvingpath.ENAMETOOLONG (pathconf())path is too long.ENOENT(pathconf()) A component ofpath does not exist, orpath is an empty string.ENOTDIR (pathconf()) A component used as a directory inpath is not in fact a directory.

ATTRIBUTES top

For an explanation of the terms used in this section, seeattributes(7). ┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface│Attribute│Value│ ├──────────────────────────────────────┼───────────────┼─────────┤ │fpathconf(),pathconf() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘

Files with name lengths longer than the value returned forname equal to_PC_NAME_MAXmay exist in the given directory. Some returned values may be huge; they are not suitable for allocating memory.

COLOPHON top

This page is part of theman-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 isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-05-17fpathconf(3)