PATHCONF(2) BSD System Calls Manual PATHCONF(2)NAME
pathconf, fpathconf — get configurable pathname variables
LIBRARY
Standard C Library (libc, -lc)
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 applica‐
tions 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 <unistd.h> header.
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 filename, not including a termi‐
nating null character.
_PC_PATH_MAX
The maximum number of bytes in a pathname, including the termi‐
nating null character.
_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 0 if filenames longer than {NAME_MAX} are silently trun‐
cated, or non-zero if an error is generated when {NAME_MAX} is
exceeded.
_PC_VDISABLE
Returns the terminal character disabling value.
_PC_SYNC_IO
Returns 1 if synchronized I/O is supported, otherwise 0.
_PC_FILESIZEBITS
If the maximum size file that could ever exist on the mounted
file system is maxsize, then the returned value is 2 plus the
floor of the base 2 logarithm of maxsize.
_PC_SYMLINK_MAX
The maximum number of bytes in a symbolic link.
_PC_2_SYMLINKS
When referring to a directory the system supports the creation of
symbolic links within that directory; for nondirectory files, the
meaning of {_PC_2_SYMLINKS} is undefined.
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, or the
implementation does not support an association of the
variable name with the associated file.
pathconf() will fail if:
[EACCES] Search permission is denied for a component of the path
prefix.
[EIO] An I/O error occurred while reading from or writing to
the file system.
[ELOOP] Too many symbolic links were encountered in translating
the pathname.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
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 ALSOsysctl(3)STANDARDS
The pathconf() and fpathconf() functions conform to ISO/IEC 9945-1:1990
(“POSIX.1”).
HISTORY
The pathconf and fpathconf functions first appeared in 4.4BSD.
BSD July 26, 2010 BSD
