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PATHCONF(2) System Calls Manual PATHCONF(2)

pathconf, lpathconf, fpathconfget configurable pathname variables

library “libc”

#include <unistd.h>

long
pathconf(const char *path, int name);

long
lpathconf(const char *path, int name);

long
fpathconf(int fd, int name);

The (), lpathconf() 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 () and lpathconf(), the path argument is the name of a file or directory. For (), 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 () system call is like pathconf() except in the case where the named file is a symbolic link, in which case lpathconf() returns information about the link, while pathconf() returns information about the file the link references.

The available values are as follows:

The maximum file link count.
The maximum number of bytes in terminal canonical input line.
The minimum 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(), lpathconf() 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() and lpathconf() 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.

getconf(1), confstr(3), sysconf(3), sysctl(3)

The pathconf() and fpathconf() functions first appeared in 4.4BSD. The lpathconf() system call first appeared in DragonFly 3.5.

May 12, 2019 DragonFly-5.6.1