1.\" $NetBSD: realpath.3,v 1.16 2013/03/05 03:11:27 enami Exp $ 2.\" 3.\" Copyright (c) 1994 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Jan-Simon Pendry. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" from: @(#)realpath.3 8.2 (Berkeley) 2/16/94 34.\" 35.Dd June 21, 2012 36.Dt REALPATH 3 37.Os 38.Sh NAME 39.Nm realpath 40.Nd returns the canonicalized absolute pathname 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In sys/param.h 45.In stdlib.h 46.Ft "char *" 47.Fn realpath "const char * restrict pathname" "char * restrict resolvedname" 48.Sh DESCRIPTION 49The 50.Fn realpath 51function resolves all symbolic links, extra 52.Dq / 53characters and references to 54.Pa /./ 55and 56.Pa /../ 57in 58.Fa pathname , 59and copies the resulting absolute pathname into 60the memory referenced by 61.Fa resolvedname . 62The 63.Fa resolvedname 64argument 65.Em must 66refer to a buffer capable of storing at least 67.Dv MAXPATHLEN 68characters, or be 69.Dv NULL . 70.Pp 71The 72.Fn realpath 73function will resolve both absolute and relative paths 74and return the absolute pathname corresponding to 75.Fa pathname . 76.Sh RETURN VALUES 77If 78.Fa resolvedname 79is 80.Dv NULL , 81it will be allocated and the returned pointer can be deallocated using 82.Xr free 3 . 83The 84.Fn realpath 85function returns 86.Fa resolvedname 87on success. 88If an error occurs, 89.Fn realpath 90returns 91.Dv NULL , 92and 93.Fa resolvedname 94was not allocated by 95.Fn realpath , 96it will contain the pathname which caused the problem. 97.Sh ERRORS 98The function 99.Fn realpath 100may fail and set the external variable 101.Va errno 102for any of the errors specified for the library functions 103.Xr chdir 2 , 104.Xr close 2 , 105.Xr fchdir 2 , 106.Xr lstat 2 , 107.Xr malloc 3 , 108.Xr open 2 , 109.Xr readlink 2 110and 111.Xr getcwd 3 . 112.Sh SEE ALSO 113.Xr getcwd 3 114.Sh STANDARDS 115.Fn realpath 116first appeared in 117.St -xpg4.2 118and is part of 119.St -p1003.1-2001 . 120.Sh HISTORY 121The 122.Fn realpath 123function call first appeared in 124.Bx 4.4 . 125In 126.Nx 7.0 127the function was updated to accept a 128.Dv NULL 129pointer for the 130.Fa resolvedname 131argument. 132.Sh BUGS 133This implementation of 134.Fn realpath 135differs slightly from the Solaris implementation. 136The 137.Bx 4.4 138version always returns absolute pathnames, 139whereas the Solaris implementation will, 140under certain circumstances, return a relative 141.Fa resolvedname 142when given a relative 143.Fa pathname . 144