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PATHCONF(2)		  FreeBSD System Calls Manual		   PATHCONF(2)

NAME
     pathconf, lpathconf, fpathconf -- get configurable	pathname variables

LIBRARY
     Standard C	Library	(libc, -lc)

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
     The pathconf(), lpathconf() and fpathconf() system	calls 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 descrip-
     tor.  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 privilege is required for the chown(2)
	     system call, otherwise 0.	IEEE Std 1003.1-2001 (``POSIX.1'')
	     requires appropriate privilege in all cases, but this behavior
	     was optional in prior editions of the standard.

     _PC_NO_TRUNC
	     Return greater than zero if attempts to use pathname components
	     longer than {NAME_MAX} will result	in an [ENAMETOOLONG] error;
	     otherwise,	such components	will be	truncated to {NAME_MAX}.  IEEE
	     Std 1003.1-2001 (``POSIX.1'') requires the	error in all cases,
	     but this behavior was optional in prior editions of the standard,
	     and some non-POSIX-compliant file systems do not support this
	     behavior.

     _PC_VDISABLE
	     Returns the terminal character disabling value.

     _PC_ASYNC_IO
	     Return 1 if asynchronous I/O is supported,	otherwise 0.

     _PC_PRIO_IO
	     Returns 1 if prioritised I/O is supported for this	file, other-
	     wise 0.

     _PC_SYNC_IO
	     Returns 1 if synchronised I/O is supported	for this file, other-
	     wise 0.

     _PC_ALLOC_SIZE_MIN
	     Minimum number of bytes of	storage	allocated for any portion of a
	     file.

     _PC_FILESIZEBITS
	     Number of bits needed to represent	the maximum file size.

     _PC_REC_INCR_XFER_SIZE
	     Recommended increment for file transfer sizes between
	     _PC_REC_MIN_XFER_SIZE and _PC_REC_MAX_XFER_SIZE.

     _PC_REC_MAX_XFER_SIZE
	     Maximum recommended file transfer size.

     _PC_REC_MIN_XFER_SIZE
	     Minimum recommended file transfer size.

     _PC_REC_XFER_ALIGN
	     Recommended file transfer buffer alignment.

     _PC_SYMLINK_MAX
	     Maximum number of bytes in	a symbolic link.

     _PC_ACL_EXTENDED
	     Returns 1 if an Access Control List (ACL) can be set on the spec-
	     ified file, otherwise 0.

     _PC_ACL_NFS4
	     Returns 1 if an NFSv4 ACLs	can be set on the specified file, oth-
	     erwise 0.

     _PC_ACL_PATH_MAX
	     Maximum number of ACL entries per file.

     _PC_CAP_PRESENT
	     Returns 1 if a capability state can be set	on the specified file,
	     otherwise 0.

     _PC_INF_PRESENT
	     Returns 1 if an information label can be set on the specified
	     file, otherwise 0.

     _PC_MAC_PRESENT
	     Returns 1 if a Mandatory Access Control (MAC) label can be	set on
	     the specified file, otherwise 0.

     _PC_MIN_HOLE_SIZE
	     If	a file system supports the reporting of	holes (see lseek(2)),
	     pathconf()	and fpathconf()	return a positive number that repre-
	     sents the minimum hole size returned in bytes.  The offsets of
	     holes returned will be aligned to this same value.	 A special
	     value of 1	is returned if the file	system does not	specify	the
	     minimum hole size but still reports holes.

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 vari-
     able value	is returned.

ERRORS
     If	any of the following conditions	occur, the pathconf() and fpathconf()
     system calls 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.

     The pathconf() system call	will fail if:

     [ENOTDIR]		A component of the path	prefix is not a	directory.

     [ENAMETOOLONG]	A component of a pathname exceeded {NAME_MAX} charac-
			ters (but see _PC_NO_TRUNC above), or an entire	path
			name exceeded {PATH_MAX} 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 translat-
			ing the	pathname.

     [EIO]		An I/O error occurred while reading from or writing to
			the file system.

     The fpathconf() system call will fail if:

     [EBADF]		The fd argument	is not a valid open file descriptor.

     [EIO]		An I/O error occurred while reading from or writing to
			the file system.

SEE ALSO
     lseek(2), sysctl(3)

HISTORY
     The pathconf() and	fpathconf() system calls first appeared	in 4.4BSD.
     The lpathconf() system call first appeared	in FreeBSD 8.0.

FreeBSD	10.1			 July 7, 2009			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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