1REALPATH(P)                POSIX Programmer's Manual               REALPATH(P)
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NAME

6       realpath - resolve a pathname
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SYNOPSIS

9       #include <stdlib.h>
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11       char *realpath(const char *restrict file_name,
12              char *restrict resolved_name);
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DESCRIPTION

16       The  realpath()  function shall derive, from the pathname pointed to by
17       file_name, an absolute pathname that names the same file, whose resolu‐
18       tion  does  not  involve '.' , '..'  , or symbolic links. The generated
19       pathname shall be stored as a null-terminated string, up to  a  maximum
20       of {PATH_MAX} bytes, in the buffer pointed to by resolved_name.
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22       If  resolved_name  is  a  null  pointer,  the behavior of realpath() is
23       implementation-defined.
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RETURN VALUE

26       Upon successful completion, realpath() shall return a  pointer  to  the
27       resolved  name.  Otherwise,  realpath() shall return a null pointer and
28       set errno to indicate the error, and the contents of the buffer pointed
29       to by resolved_name are undefined.
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ERRORS

32       The realpath() function shall fail if:
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34       EACCES Read  or  search  permission  was  denied  for  a  component  of
35              file_name.
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37       EINVAL The file_name argument is a null pointer.
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39       EIO    An error occurred while reading from the file system.
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41       ELOOP  A loop exists in symbolic links encountered during resolution of
42              the path argument.
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44       ENAMETOOLONG
45              The  length  of  the  file_name argument exceeds {PATH_MAX} or a
46              pathname component is longer than {NAME_MAX}.
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48       ENOENT A component of file_name does  not  name  an  existing  file  or
49              file_name points to an empty string.
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51       ENOTDIR
52              A component of the path prefix is not a directory.
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55       The realpath() function may fail if:
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57       ELOOP  More  than  {SYMLOOP_MAX} symbolic links were encountered during
58              resolution of the path argument.
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60       ENAMETOOLONG
61              Pathname resolution of a symbolic link produced an  intermediate
62              result whose length exceeds {PATH_MAX}.
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64       ENOMEM Insufficient storage space is available.
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66
67       The following sections are informative.
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EXAMPLES

70   Generating an Absolute Pathname
71       The following example generates an absolute pathname for the file iden‐
72       tified by the symlinkpath argument. The generated pathname is stored in
73       the actualpath array.
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75
76              #include <stdlib.h>
77              ...
78              char *symlinkpath = "/tmp/symlink/file";
79              char actualpath [PATH_MAX+1];
80              char *ptr;
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82
83              ptr = realpath(symlinkpath, actualpath);
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APPLICATION USAGE

86       None.
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RATIONALE

89       Since  the  maximum  pathname  length is arbitrary unless {PATH_MAX} is
90       defined, an application generally cannot supply a resolved_name  buffer
91       with size {{PATH_MAX}+1}.
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FUTURE DIRECTIONS

94       In   the   future,  passing  a  null  pointer  to  realpath()  for  the
95       resolved_name argument may be defined to have realpath() allocate space
96       for the generated pathname.
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SEE ALSO

99       getcwd()    ,    sysconf()   ,   the   Base   Definitions   volume   of
100       IEEE Std 1003.1-2001, <stdlib.h>
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103       Portions of this text are reprinted and reproduced in  electronic  form
104       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
105       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
106       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
107       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
108       event of any discrepancy between this version and the original IEEE and
109       The Open Group Standard, the original IEEE and The Open Group  Standard
110       is  the  referee document. The original Standard can be obtained online
111       at http://www.opengroup.org/unix/online.html .
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115IEEE/The Open Group                  2003                          REALPATH(P)
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