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.\" Jan-Simon Pendry.
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.\"     from: @(#)realpath.3	8.2 (Berkeley) 2/16/94
.\"
.Dd May 24, 2013
.Dt REALPATH 3
.Os
.Sh NAME
.Nm realpath
.Nd returns the canonicalized absolute pathname
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In stdlib.h
.Ft "char *"
.Fn realpath "const char * restrict pathname" "char * restrict resolvedname"
.Sh DESCRIPTION
The
.Fn realpath
function resolves all symbolic links, extra
.Dq /
characters and references to
.Pa /./
and
.Pa /../
in
.Fa pathname ,
and copies the resulting absolute pathname into
the memory referenced by
.Fa resolvedname .
The
.Fa resolvedname
argument
.Em must
refer to a buffer capable of storing at least
.Dv MAXPATHLEN
characters, or be
.Dv NULL .
.Pp
The
.Fn realpath
function will resolve both absolute and relative paths
and return the absolute pathname corresponding to
.Fa pathname .
.Sh RETURN VALUES
If
.Fa resolvedname
is
.Dv NULL ,
it will be allocated and the returned pointer can be deallocated using
.Xr free 3 .
The
.Fn realpath
function returns
.Fa resolvedname
on success.
If an error occurs,
.Fn realpath
returns
.Dv NULL ,
and if
.Fa resolvedname
was not allocated by
.Fn realpath ,
it will contain the pathname which caused the problem.
.Sh ERRORS
The function
.Fn realpath
may fail and set the external variable
.Va errno
for any of the errors specified for the library functions
.\" First sorted by section, then by name.
.Xr lstat 2 ,
.Xr readlink 2 ,
.Xr getcwd 3
and
.Xr malloc 3 .
.Pp
In addition, the following errors may be reported:
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa pathname
argument is
.Dv NULL .
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the
.Fa pathname .
.It Bq Er ENAMETOOLONG
The resulting absolute pathname exceeds
.Dv MAXPATHLEN
characters.
.It Bq Er ENOENT
The value of the
.Fa pathname
argument is an empty string;
or a symbolic link to an empty string is encountered.
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.El
.Sh SEE ALSO
.Xr getcwd 3
.Sh STANDARDS
.Fn realpath
first appeared in
.St -xpg4.2
and is part of
.St -p1003.1-2001 .
.Sh HISTORY
The
.Fn realpath
function call first appeared in
.Bx 4.4 .
In
.Nx 7.0
the function was updated to accept a
.Dv NULL
pointer for the
.Fa resolvedname
argument.
.Sh BUGS
This implementation of
.Fn realpath
differs slightly from the Solaris implementation.
The
.Bx 4.4
version always returns absolute pathnames,
whereas the Solaris implementation will,
under certain circumstances, return a relative
.Fa resolvedname
when given a relative
.Fa pathname .