1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/pathconf.2,v 1.4.2.6 2001/12/14 18:34:01 ru Exp $ 34.\" 35.Dd April 13, 2013 36.Dt PATHCONF 2 37.Os 38.Sh NAME 39.Nm pathconf , 40.Nm lpathconf , 41.Nm fpathconf 42.Nd get configurable pathname variables 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In unistd.h 47.Ft long 48.Fn pathconf "const char *path" "int name" 49.Ft long 50.Fn lpathconf "const char *path" "int name" 51.Ft long 52.Fn fpathconf "int fd" "int name" 53.Sh DESCRIPTION 54The 55.Fn pathconf , 56.Fn lpathconf 57and 58.Fn fpathconf 59functions provide a method for applications to determine the current 60value of a configurable system limit or option variable associated 61with a pathname or file descriptor. 62.Pp 63For 64.Fn pathconf 65and 66.Fn lpathconf , 67the 68.Fa path 69argument is the name of a file or directory. 70For 71.Fn fpathconf , 72the 73.Fa fd 74argument is an open file descriptor. 75The 76.Fa name 77argument specifies the system variable to be queried. 78Symbolic constants for each name value are found in the include file 79.In unistd.h . 80.Pp 81The 82.Fn lpathconf 83system call is like 84.Fn pathconf 85except in the case where the named file is a symbolic link, 86in which case 87.Fn lpathconf 88returns information about the link, 89while 90.Fn pathconf 91returns information about the file the link references. 92.Pp 93The available values are as follows: 94.Bl -tag -width 6n 95.It Li _PC_LINK_MAX 96The maximum file link count. 97.It Li _PC_MAX_CANON 98The maximum number of bytes in terminal canonical input line. 99.It Li _PC_MAX_INPUT 100The minimum maximum number of bytes for which space is available in 101a terminal input queue. 102.It Li _PC_NAME_MAX 103The maximum number of bytes in a file name. 104.It Li _PC_PATH_MAX 105The maximum number of bytes in a pathname. 106.It Li _PC_PIPE_BUF 107The maximum number of bytes which will be written atomically to a pipe. 108.It Li _PC_CHOWN_RESTRICTED 109Return 1 if appropriate privileges are required for the 110.Xr chown 2 111system call, otherwise 0. 112.It Li _PC_NO_TRUNC 113Return 1 if file names longer than KERN_NAME_MAX are truncated. 114.It Li _PC_VDISABLE 115Returns the terminal character disabling value. 116.El 117.Sh RETURN VALUES 118If the call to 119.Fn pathconf 120or 121.Fn fpathconf 122is not successful, \-1 is returned and 123.Va errno 124is set appropriately. 125Otherwise, if the variable is associated with functionality that does 126not have a limit in the system, \-1 is returned and 127.Va errno 128is not modified. 129Otherwise, the current variable value is returned. 130.Sh ERRORS 131If any of the following conditions occur, the 132.Fn pathconf , 133.Fn lpathconf 134and 135.Fn fpathconf 136functions shall return -1 and set 137.Va errno 138to the corresponding value. 139.Bl -tag -width Er 140.It Bq Er EINVAL 141The value of the 142.Fa name 143argument is invalid. 144.It Bq Er EINVAL 145The implementation does not support an association of the variable 146name with the associated file. 147.El 148.Pp 149.Fn Pathconf 150and 151.Fn lpathconf 152will fail if: 153.Bl -tag -width Er 154.It Bq Er ENOTDIR 155A component of the path prefix is not a directory. 156.It Bq Er ENAMETOOLONG 157A component of a pathname exceeded 255 characters, 158or an entire path name exceeded 1023 characters. 159.It Bq Er ENOENT 160The named file does not exist. 161.It Bq Er EACCES 162Search permission is denied for a component of the path prefix. 163.It Bq Er ELOOP 164Too many symbolic links were encountered in translating the pathname. 165.It Bq Er EIO 166An I/O error occurred while reading from or writing to the file system. 167.El 168.Pp 169.Fn Fpathconf 170will fail if: 171.Bl -tag -width Er 172.It Bq Er EBADF 173.Fa fd 174is not a valid open file descriptor. 175.It Bq Er EIO 176An I/O error occurred while reading from or writing to the file system. 177.El 178.Sh SEE ALSO 179.Xr sysctl 3 180.Sh HISTORY 181The 182.Fn pathconf 183and 184.Fn fpathconf 185functions first appeared in 186.Bx 4.4 . 187The 188.Fn lpathconf 189system call first appeared in 190.Dx 3.5 . 191