NAME
pathconf,
lpathconf, fpathconf
— get configurable pathname
variables
LIBRARY
library “libc”
SYNOPSIS
#include
<unistd.h>
long
pathconf(const
char *path, int
name);
long
lpathconf(const
char *path, int
name);
long
fpathconf(int
fd, int name);
DESCRIPTION
Thepathconf(),
lpathconf() and
fpathconf()
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()
and lpathconf(), 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
lpathconf()
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:
_PC_LINK_MAX- The maximum file link count.
_PC_MAX_CANON- The maximum number of bytes in terminal canonical input line.
_PC_MAX_INPUT- The minimum maximum number of bytes for which space is available in a terminal input queue.
_PC_NAME_MAX- The maximum number of bytes in a file name.
_PC_PATH_MAX- The maximum number of bytes in a pathname.
_PC_PIPE_BUF- The maximum number of bytes which will be written atomically to a pipe.
_PC_CHOWN_RESTRICTED- Return 1 if appropriate privileges are required for the chown(2) system call, otherwise 0.
_PC_NO_TRUNC- Return 1 if file names longer than KERN_NAME_MAX are truncated.
_PC_VDISABLE- Returns the terminal character disabling value.
RETURN VALUES
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.
ERRORS
If any of the following conditions occur, the
pathconf(), lpathconf() and
fpathconf() functions shall return -1 and set
errno to the corresponding value.
- [
EINVAL] - The value of the name argument is invalid.
- [
EINVAL] - The implementation does not support an association of the variable name with the associated file.
Pathconf() and
lpathconf() will fail if:
- [
ENOTDIR] - A component of the path prefix is not a directory.
- [
ENAMETOOLONG] - A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
- [
ENOENT] - The named file does not exist.
- [
EACCES] - Search permission is denied for a component of the path prefix.
- [
ELOOP] - Too many symbolic links were encountered in translating the pathname.
- [
EIO] - An I/O error occurred while reading from or writing to the file system.
Fpathconf() will fail if:
- [
EBADF] - fd is not a valid open file descriptor.
- [
EIO] - An I/O error occurred while reading from or writing to the file system.
SEE ALSO
HISTORY
The pathconf() and
fpathconf() functions first appeared in
4.4BSD. The lpathconf()
system call first appeared in DragonFly 3.5.