1.\" Copyright (c) 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Jan-Simon Pendry. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd March 18, 2026 32.Dt REALPATH 3 33.Os 34.Sh NAME 35.Nm realpath 36.Nd returns the canonicalized absolute pathname 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In stdlib.h 41.Ft "char *" 42.Fn realpath "const char * restrict pathname" "char * restrict resolved_path" 43.Sh DESCRIPTION 44The 45.Fn realpath 46function resolves all symbolic links, extra 47.Dq / 48characters and references to 49.Pa /./ 50and 51.Pa /../ 52in 53.Fa pathname , 54and copies the resulting absolute pathname into 55the memory pointed to by 56.Fa resolved_path . 57The 58.Fa resolved_path 59argument 60.Em must 61point to a buffer capable of storing at least 62.Dv PATH_MAX 63characters, or be 64.Dv NULL . 65.Pp 66The 67.Fn realpath 68function will resolve both absolute and relative paths 69and return the absolute pathname corresponding to 70.Fa pathname . 71All components of 72.Fa pathname 73must exist when 74.Fn realpath 75is called, and all but the last component must name either directories or 76symlinks pointing to the directories. 77.Sh "RETURN VALUES" 78On success, the 79.Fn realpath 80function returns 81.Fa resolved_path 82if it was not 83.Dv NULL , 84or a pointer to a null-terminated string which must be freed by the 85caller if it was. 86If an error occurs, 87.Fn realpath 88returns 89.Dv NULL , 90and if 91.Fa resolved_path 92was not 93.Dv NULL , 94the array that it points to contains the pathname which caused the 95problem. 96.Sh ERRORS 97The function 98.Fn realpath 99may fail and set the external variable 100.Va errno 101for any of the errors specified for the library functions 102.Xr lstat 2 , 103.Xr readlink 2 104and 105.Xr getcwd 3 . 106.Sh SEE ALSO 107.Xr basename 3 , 108.Xr dirname 3 , 109.Xr free 3 , 110.Xr getcwd 3 111.Sh STANDARDS 112The 113.Fn realpath 114function conforms to 115.St -p1003.1-2001 . 116.Sh HISTORY 117The 118.Fn realpath 119function first appeared in 120.Bx 4.4 . 121