pathconf(2)							System Calls Manual						       pathconf(2)

NAME

       pathconf(), fpathconf() - get configurable path name variables

SYNOPSIS

DESCRIPTION

       The  and  functions  provide  a	method for applications to determine the value of a configurable limit or option associated with a file or
       directory (see limits(5) and

       For the path argument points to the path name of a file or directory.

       For the fildes argument is an open file descriptor.

       For both functions, the name argument represents the variable to be queried regarding the file or directory to  which  the  other  argument
       refers.

       The following table lists the configuration variables available from and and lists for each variable the associated value of the name argu-
       ment:
									|		       |
						       Variable 	|    Value of name     |  Notes
						------------------------+----------------------+----------
						LINK_MAX		| _PC_LINK_MAX	       | 1
						MAX_CANON		| _PC_MAX_CANON        | 2
						MAX_INPUT		| _PC_MAX_INPUT        | 2
									| _PC_FILESIZEBITS     | 3, 4, 10
						NAME_MAX		| _PC_NAME_MAX	       | 3, 4
						PATH_MAX		| _PC_PATH_MAX	       | 4, 5
						PIPE_BUF		| _PC_PIPE_BUF	       | 6
						_POSIX_ASYNC_IO 	| _PC_ASYNC_IO	       | 1, 11
						_POSIX_CHOWN_RESTRICTED | _PC_CHOWN_RESTRICTED | 7, 8
						_POSIX_NO_TRUNC 	| _PC_NO_TRUNC	       | 3, 4
						_POSIX_PRIO_IO		| _PC_PRIO_IO	       | 1, 12
						_POSIX_SYNC_IO		| _PC_SYNC_IO	       | 9
						_POSIX_VDISABLE 	| _PC_V_DISABLE        | 2

       The variables in the table are defined as constants in or if they do not vary from one path name to another.  The associated values of  the
       name argument are defined in

RETURN VALUE

       The following notes further qualify the table above.

	      1.   If path or fildes refers to a directory, the value returned applies to the directory itself.

	      2.   If  the  variable  is  constant,  the  value returned is identical to the variable's definition in or regardless of the type of
		   fildes or path.  The behavior is undefined if path or fildes does not refer to a terminal file.

	      3.   If path or fildes refers to a directory, the value returned applies to the file names within the directory.

	      4.   If path or fildes does not refer to a directory, or returns -1 and sets to

	      5.   If path or fildes refers to a directory, the value returned is the maximum length of a relative path name  when  the  specified
		   directory is the working directory.

	      6.   If  path  refers  to  a FIFO, or if fildes refers to a pipe or FIFO, the value returned applies to the pipe or FIFO itself.	If
		   path or fildes refers to a directory, the value returned applies to any FIFOs that exist or can be created  within  the  direc-
		   tory.  If is a constant, the value returned is identical to the definition of in regardless of the type of fildes or path.  The
		   behavior is undefined for a file other than a directory, FIFO, or pipe.

	      7.   If path or fildes refers to a directory, the value returned applies to files of any type, other than directories, that exist or
		   can be created within the directory.

	      8.   is  defined	if  the  privilege  group has been granted the privilege (see getprivgrp(2) and chown(2)).  In all other cases, is
		   undefined and or returns -1 without changing To determine if can be performed on a file, it is simplest to attempt  the  opera-
		   tion and check the return value for failure or success.

	      9.   when defined, determines whether synchronized IO operations may be performed for the associated file (see open(2)).	If path or
		   fildes refers to a directory, it is unspecified whether or not the implementation supports an association of the variable  name
		   with the specified file.

	      10.  For	file systems that are not large file enabled, the return value will be less than or equal to 32. For file systems that are
		   large file enabled, the return value will be between 33 and 63.

	      11.  when defined, determines whether asynchronous I/O operations may be performed for the associated file.

	      12.  when defined, determines whether prioritized I/O is supported for the associated file.

       If the variable corresponding to name is not defined for path or fildes, the and functions succeed and return a value of -1, without chang-
       ing the value of

       Upon  any  other successful completion, these functions return the value of the named variable with respect to the specified file or direc-
       tory, as described above.

       Otherwise, a value of -1 is returned and is set to indicate the error.

ERRORS

       The and fail if any of the following conditions are encountered:

	      A component of the path prefix denies search permission.

	      The		     fildes argument is not a valid open file descriptor.

	      path		     points outside the allocated address space of the process.

	      The value of	     name is not valid or the implementation does not support an association of the variable name with the  speci-
				     fied file.

	      Too many symbolic links were encountered in translating
				     path.

	      The length of the specified path name exceeds
				     bytes, or the length of a component of the path name exceeds bytes while is in effect.

	      The file named by      path does not exist (for example, path is null, or a component of path does not exist).

	      A component of the path prefix is not a directory.

EXAMPLES

       The  following example sets val to the value of for the device file being used as the standard input.  If the standard input is a terminal,
       this value is the maximum number of input characters that can be entered on a single input line before typing the newline character:

       The following code segment shows two calls to pathconf.	The first determines whether a file name longer than bytes will  be  truncated	to
       bytes in the directory.	If so, the second call is made to determine the actual value of so that an error can be printed if a user-supplied
       file name stored in filebuf will be truncated in this directory:

DEPENDENCIES

   NFS
       The following error can occur:

	      path		or fildes refers to a file for which a value for name cannot be determined.  In particular, and cannot	be  deter-
				mined for an NFS file.

AUTHOR

       and were developed by HP.

SEE ALSO

       chown(2), errno(2), limits(5), unistd(5), termio(7).

STANDARDS CONFORMANCE

																       pathconf(2)