.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "REALPATH" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" realpath 
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.SH NAME
realpath \- resolve a pathname
.SH SYNOPSIS
.LP
\fB#include <stdlib.h>
.br
.sp
char *realpath(const char *restrict\fP \fIfile_name\fP\fB,
.br
\ \ \ \ \ \  char *restrict\fP \fIresolved_name\fP\fB); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
The \fIrealpath\fP() function shall derive, from the pathname pointed
to by \fIfile_name\fP, an absolute pathname that names
the same file, whose resolution does not involve \fB'.'\fP, \fB'..'\fP,
or symbolic links. The generated pathname shall be
stored as a null-terminated string, up to a maximum of {PATH_MAX}
bytes, in the buffer pointed to by \fIresolved_name\fP.
.LP
If \fIresolved_name\fP is a null pointer, the behavior of \fIrealpath\fP()
is implementation-defined.
.SH RETURN VALUE
.LP
Upon successful completion, \fIrealpath\fP() shall return a pointer
to the resolved name. Otherwise, \fIrealpath\fP() shall
return a null pointer and set \fIerrno\fP to indicate the error, and
the contents of the buffer pointed to by \fIresolved_name\fP
are undefined.
.SH ERRORS
.LP
The \fIrealpath\fP() function shall fail if:
.TP 7
.B EACCES
Read or search permission was denied for a component of \fIfile_name\fP.
.TP 7
.B EINVAL
The \fIfile_name\fP argument is a null pointer.
.TP 7
.B EIO
An error occurred while reading from the file system.
.TP 7
.B ELOOP
A loop exists in symbolic links encountered during resolution of the
\fIpath\fP argument.
.TP 7
.B ENAMETOOLONG
The length of the \fIfile_name\fP argument exceeds {PATH_MAX} or a
pathname component is longer than {NAME_MAX}.
.TP 7
.B ENOENT
A component of \fIfile_name\fP does not name an existing file or \fIfile_name\fP
points to an empty string.
.TP 7
.B ENOTDIR
A component of the path prefix is not a directory.
.sp
.LP
The \fIrealpath\fP() function may fail if:
.TP 7
.B ELOOP
More than {SYMLOOP_MAX} symbolic links were encountered during resolution
of the \fIpath\fP argument.
.TP 7
.B ENAMETOOLONG
Pathname resolution of a symbolic link produced an intermediate result
whose length exceeds {PATH_MAX}.
.TP 7
.B ENOMEM
Insufficient storage space is available.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.SS Generating an Absolute Pathname
.LP
The following example generates an absolute pathname for the file
identified by the \fIsymlinkpath\fP argument. The generated
pathname is stored in the \fIactualpath\fP array.
.sp
.RS
.nf

\fB#include <stdlib.h>
\&...
char *symlinkpath = "/tmp/symlink/file";
char actualpath [PATH_MAX+1];
char *ptr;
.sp

ptr = realpath(symlinkpath, actualpath);
\fP
.fi
.RE
.SH APPLICATION USAGE
.LP
None.
.SH RATIONALE
.LP
Since the maximum pathname length is arbitrary unless {PATH_MAX} is
defined, an application generally cannot supply a
\fIresolved_name\fP buffer with size {{PATH_MAX}+1}.
.SH FUTURE DIRECTIONS
.LP
In the future, passing a null pointer to \fIrealpath\fP() for the
\fIresolved_name\fP argument may be defined to have
\fIrealpath\fP() allocate space for the generated pathname.
.SH SEE ALSO
.LP
\fIgetcwd\fP(), \fIsysconf\fP(), the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<stdlib.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .