directory(3C)                    DG/UX 5.4.2                   directory(3C)


NAME
       directory: opendir, readdir, telldir, seekdir, rewinddir, closedir -
       directory operations

SYNOPSIS
       #include <sys/types.h>
       #include <dirent.h>

       DIR *opendir (const char *filename);

       struct dirent *readdir (DIR *dirp);

       long telldir (DIR *dirp);

       void seekdir (DIR *dirp, long loc);

       void rewinddir (DIR *dirp);

       int closedir (DIR *dirp);


   Alternate Syntax
       #include <sys/dir.h>
       struct direct *readdir (DIR *dirp);

DESCRIPTION
       opendir opens the directory named by filename and associates a
       directory stream with it.  opendir returns a pointer to be used to
       identify the directory stream in subsequent operations.  The
       directory stream is positioned at the first entry.  A null pointer is
       returned if filename cannot be accessed or is not a directory, or if
       it cannot malloc(3C) enough memory to hold a DIR structure or a
       buffer for the directory entries.

       readdir returns a pointer to the next active directory entry and
       positions the directory stream at the next entry.  No inactive
       entries are returned.  It returns NULL upon reaching the end of the
       directory or upon detecting an invalid location in the directory.
       readdir buffers several directory entries per actual read operation;
       readdir marks for update the statime field of the directory each
       time the directory is actually read.

       telldir returns the current location associated with the named
       directory stream.

       seekdir sets the position of the next readdir operation on the
       directory stream.  The new position reverts to the position
       associated with the directory stream at the time the telldir
       operation that provides loc was performed.  Values returned by
       telldir are valid only if the directory has not changed because of
       compaction or expansion.  This situation is not a problem with System
       V, but it can be with DG/UX and some file system types.

       rewinddir resets the position of the named directory stream to the



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directory(3C)                    DG/UX 5.4.2                   directory(3C)


       beginning of the directory.  It also causes the directory stream to
       refer to the current state of the corresponding directory, as a call
       to opendir would.

       closedir closes the named directory stream and frees the DIR
       structure.

       The following errors can occur as a result of these operations.

       opendir returns NULL on failure and sets errno to one of the
       following values:

       ENOTDIR             A component of filename is not a directory.

       EACCES              A component of filename denies search permission.

       EACCES              Read permission is denied on the specified
                           directory.

       EMFILE              The maximum number of file descriptors are
                           currently open.

       ENFILE              The system file table is full.

       EFAULT              filename points outside the allocated address
                           space.

       ELOOP               Too many symbolic links were encountered in
                           translating filename.

       ENAMETOOLONG        The length of the filename argument exceeds
                           {PATHMAX}, or the length of a filename component
                           exceeds {NAMEMAX} while {POSIXNOTRUNC} is in
                           effect.

       ENOENT              A component of filename does not exist or is a
                           null pathname.

       readdir returns NULL on failure and sets errno to one of the
       following values:

       ENOENT              The current file pointer for the directory is not
                           located at a valid entry.

       EBADF               The file descriptor determined by the DIR stream
                           is no longer valid.  This result occurs if the
                           DIR stream has been closed.

       telldir, seekdir, and  closedir return -1 on failure and set errno to
       the following value:

       EBADF               The file descriptor determined by the DIR stream
                           is no longer valid.  This results if the DIR
                           stream has been closed.



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directory(3C)                    DG/UX 5.4.2                   directory(3C)


EXAMPLE
       Here is a sample program that prints the names of all the files in
       the current directory:

              #include <stdio.h>
              #include <dirent.h>

              main()
              {
                   DIR *dirp;
                   struct dirent *direntp;

                   dirp = opendir( "." );
                   while ( (direntp = readdir( dirp )) != NULL )
                        (void)printf( "%s\n", direntp->dname );
                   closedir( dirp );
                   return (0);
              }

SEE ALSO
       getdents(2), dirent(4).

NOTES
       rewinddir is implemented as a macro, so its function address cannot
       be taken.
































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