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.TH REALPATH 3C "Dec 20, 2014"
.SH NAME
realpath \- resolve pathname
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>

\fBchar *\fR\fBrealpath\fR(\fBconst char *restrict\fR \fIfile_name\fR,
     \fBchar *restrict\fR \fIresolved_name\fR);

\fBchar *\fR\fBcanonicalize_file_name\fR(\fBconst char *\fR\fIpath\fR);
.fi

.SH DESCRIPTION
.LP
The \fBrealpath()\fR function derives, from the pathname pointed to by
\fIfile_name\fR, an absolute pathname that names the same file, whose
resolution does not involve "\fB\&.\fR", "\fB\&..\fR", or symbolic links. The
generated pathname is stored as a null-terminated string, up to a maximum of
{\fBPATH_MAX\fR} bytes (defined in \fBlimits.h\fR(3HEAD)), in the buffer
pointed to by \fIresolved_name\fR.
.sp
.LP
The \fBcanonicalize_file_name()\fR function is equivalent to calling
\fBrealpath\fR(\fIpath\fR, \fINULL\fR). This function is only provided for
compatibility.
.SH RETURN VALUES
.LP
On successful completion, \fBrealpath()\fR returns a pointer to the resolved
name.  Otherwise, \fBrealpath()\fR returns a null pointer and sets \fBerrno\fR
to indicate the error, and the contents of the buffer pointed to by
\fIresolved_name\fR are left in an indeterminate state.
.SH ERRORS
.LP
The \fBrealpath()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEACCES\fR\fR
.ad
.RS 16n
Read or search permission was denied for a component of \fIfile_name\fR.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 16n
Either the \fIfile_name\fR or \fIresolved_name\fR argument is a null pointer.
.RE

.sp
.ne 2
.na
\fB\fBEIO\fR\fR
.ad
.RS 16n
An error occurred while reading from the file system.
.RE

.sp
.ne 2
.na
\fB\fBELOOP\fR\fR
.ad
.RS 16n
Too many symbolic links were encountered in resolving \fIfile_name\fR.
.RE

.sp
.ne 2
.na
\fB\fBELOOP\fR\fR
.ad
.RS 16n
A loop exists in symbolic links encountered during resolution of the
\fIfile_name\fR argument.
.RE

.sp
.ne 2
.na
\fB\fBENAMETOOLONG\fR\fR
.ad
.RS 16n
The \fIfile_name\fR argument is longer than {\fBPATH_MAX\fR} or a pathname
component is longer than {\fBNAME_MAX\fR}.
.RE

.sp
.ne 2
.na
\fB\fBENOENT\fR\fR
.ad
.RS 16n
A component of \fIfile_name\fR does not name an existing file or
\fIfile_name\fR points to an empty string.
.RE

.sp
.ne 2
.na
\fB\fBENOTDIR\fR\fR
.ad
.RS 16n
A component of the path prefix is not a directory.
.RE

.sp
.LP
The \fBrealpath()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBENAMETOOLONG\fR\fR
.ad
.RS 16n
Pathname resolution of a symbolic link produced an intermediate result whose
length exceeds {\fBPATH_MAX\fR}.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 16n
Insufficient storage space is available.
.RE

.SH USAGE
.LP
The \fBrealpath()\fR function operates on null-terminated strings.
.sp
.LP
Execute permission is required for all the directories in the given and the
resolved path.
.sp
.LP
The \fBrealpath()\fR function might fail to return to the current directory if
an error occurs.
.SH ATTRIBUTES
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.LP
.BR getcwd (3C),
.BR sysconf (3C),
.BR limits.h (3HEAD),
.BR attributes (7),
.BR standards (7)