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PATHCONF(2) System Calls Manual PATHCONF(2)

pathconf, fpathconfget configurable pathname variables

#include <unistd.h>

pathconf(const char *path, int name);

fpathconf(int fd, int name);

The () and () functions provide a method for applications to determine the current value of a configurable system limit or option variable associated with a pathname or file descriptor.

For pathconf, the path argument is the name of a file or directory. For fpathconf, the fd argument is an open file descriptor. The name argument specifies the system variable to be queried. Symbolic constants for each name value are found in the include file ⟨unistd.h⟩.

The available values are as follows:

The maximum file link count.
The maximum number of bytes in a terminal canonical input line.
The maximum number of bytes for which space is available in a terminal input queue.
The maximum number of bytes in a file name.
The maximum number of bytes in a pathname.
The maximum number of bytes which will be written atomically to a pipe.
Return 1 if appropriate privileges are required for the chown(2) system call, otherwise 0.
Return 1 if file names longer than KERN_NAME_MAX are truncated.
Returns the terminal character disabling value.

If the call to pathconf or fpathconf is not successful, -1 is returned and errno is set appropriately. Otherwise, if the variable is associated with functionality that does not have a limit in the system, -1 is returned and errno is not modified. Otherwise, the current variable value is returned.

If any of the following conditions occur, the pathconf and fpathconf functions shall return -1 and set errno to the corresponding value.

The value of the name argument is invalid.
The implementation does not support an association of the variable name with the associated file.

pathconf() will fail if:

A component of the path prefix is not a directory.
A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
The named file does not exist.
Search permission is denied for a component of the path prefix.
Too many symbolic links were encountered in translating the pathname.
An I/O error occurred while reading from or writing to the file system.

fpathconf() will fail if:

fd is not a valid open file descriptor.
An I/O error occurred while reading from or writing to the file system.

sysconf(3), sysctl(3)

The pathconf and fpathconf functions first appeared in 4.4BSD.

May 31, 2007 OpenBSD-5.1