fpathconf, pathconf - get configuration values for files
fpathconf() gets a value for the configuration option
name for the open file descriptor
pathconf() gets a value for configuration option
name for the filename
The corresponding macros defined in
<unistd.h> are minimum values; if an application wants to take advantage of values which may change, a call to fpathconf() or pathconf() can be made, which may yield more liberal results.
name equal to one of the following constants returns the following configuration options:
The maximum number of links to the file. If
path refer to a directory, then the value applies to the whole directory. The corresponding macro is _POSIX_LINK_MAX.
The maximum length of a formatted input line, where
path must refer to a terminal. The corresponding macro is _POSIX_MAX_CANON.
The maximum length of an input line, where
path must refer to a terminal. The corresponding macro is _POSIX_MAX_INPUT.
The maximum length of a filename in the directory
fd that the process is allowed to create. The corresponding macro is _POSIX_NAME_MAX.
The maximum length of a relative pathname when
fd is the current working directory. The corresponding macro is _POSIX_PATH_MAX.
The maximum number of bytes that can be written atomically to a pipe of FIFO. For fpathconf(),
fd should refer to a pipe or FIFO. For fpathconf(),
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.
This returns a positive value if the use of chown(2) and fchown(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.
path refers to a directory, then the return value applies to all files in that directory.
This returns nonzero if accessing filenames longer than _POSIX_NAME_MAX generates an error. The corresponding macro is _POSIX_NO_TRUNC.
This returns nonzero if special character processing can be disabled, where
path must refer to a terminal.
The return value of these functions is one of the following:
On error, -1 is returned and
errno is set to indicate the cause of the error (for example, EINVAL, indicating that
name is invalid).
name corresponds to a maximum or minimum limit, and that limit is indeterminate, -1 is returned and
errno is not changed. (To distinguish an indeterminate limit from an error, set
errno to zero before the call, and then check whether
errno is nonzero when -1 is returned.)
name 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
<limits.h> when the application was compiled.
(pathconf()) Search permission is denied for one of the directories in the path prefix of
fd is not a valid file descriptor.
name is invalid.
The implementation does not support an association of
name with the specified file.
(pathconf()) Too many symbolic links were encountered while resolving
path is too long.
(pathconf()) A component of
path does not exist, or
path is an empty string.
(pathconf()) A component used as a directory in
path is not in fact a directory.
Files with name lengths longer than the value returned for
name equal to _PC_NAME_MAX may exist in the given directory.
Some returned values may be huge; they are not suitable for allocating memory.
This page is part of release 4.15 of the Linux
man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.