opendir()

Open a directory

Synopsis:

#include <dirent.h>

DIR* opendir( const char* dirname );

Library:

libc

Description:

The opendir() function is used with readdir() and closedir() to get the list of file names contained in the directory specified by dirname. The dirname can be relative to the current working directory or an absolute path.

The <dirent.h> header file contains definitions for the dirent structure. <!- removing this bit because the definition in the header file provides no useful information (it's just a hidden structure): and the DIR type. -->

More than one directory can be read at the same time using the opendir(), readdir(), rewinddir() and closedir() functions.

The result of using a directory stream after one of the exec*() or spawn*() functions is undefined. After a call to the fork() function, either the parent or the child (but not both) can continue processing the directory stream using readdir() and rewinddir(). If both the parent and child processes use these functions, the result is undefined. Either process can use closedir().

Returns:

A pointer to a DIR structure required for subsequent calls to readdir() to retrieve the file names in dirname, or NULL if dirname isn't a valid path (errno is set).

Errors:

EACCES

Search permission is denied for a component of dirname, or read permission is denied for dirname.

ELOOP

Too many levels of symbolic links or prefixes.

ENAMETOOLONG

The length of dirname exceeds PATH_MAX, or a pathname component is longer than NAME_MAX.

ENOENT

The named directory doesn't exist.

ENOSYS

The opendir() function isn't implemented for the filesystem specified in dirname.

ENOTDIR

A component of dirname isn't a directory.

Examples:

To get a list of files contained in the directory /home/fred:

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

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

    dirp = opendir( "/home/fred" );
    if( dirp == NULL ) {
        perror( "can't open /home/fred" );
    } else {
        for(;;) {
            direntp = readdir( dirp );
            if( direntp == NULL ) break;

            printf( "%s\n", direntp->d_name );
        }
        
        closedir( dirp );
    }
    
    return EXIT_SUCCESS;
}

Classification:

POSIX 1003.1

See also:

closedir(), errno, readdir(), readdir_r(), rewinddir()