NAME
pathconf,
fpathconf —
get configurable pathname
variables
SYNOPSIS
#include
<unistd.h>
long
pathconf(const
char *path, int
name);
long
fpathconf(int
fd, int name);
DESCRIPTION
The
pathconf()
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, 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:
_PC_LINK_MAX- The maximum file link count.
_PC_MAX_CANON- The maximum number of bytes in a terminal canonical input line.
_PC_MAX_INPUT- The 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_MAXare 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 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() 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.