When this extension is in use, instead of skipping directories named on the command line (or with getline), they are read, with each entry returned as a record.
The record consists of three fields. The first two are the inode number and the filename, separated by a forward slash character. On systems where the directory entry contains the file type, the record has a third field which is a single letter indicating the type of the file: f for file, d for directory, b for a block device, c for a character device, p for a FIFO, l for a symbolic link, s for a socket.
On systems without the file type information, the extension falls back to calling stat(2), in order to provide the information. Thus the third field should never be u.
By default, if a directory cannot be opened (due to permission problems, for example), gawk will exit. As with regular files, this situation can be handled using a BEGINFILE rule that checks ERRNO and prints an error or otherwise handles the problem.
@load "readdir"
...
BEGIN { FS = "/" }
{ print "file name is", $2 }
opendir(3), readdir(3), stat(2).
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