The readdir extension adds an input parser for directories.
The usage is as follows:
@load "readdir"
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 separated by forward slash characters. The first two are the inode number and the file name, and the third field is a single letter indicating the type of the file. The letters and their corresponding file types are shown in Table 17.4.
| Letter | File type |
|---|---|
b | Block device |
c | Character device |
d | Directory |
f | Regular file |
l | Symbolic link |
p | Named pipe (FIFO) |
s | Socket |
Table 17.4: File types returned by the readdir extension
On systems where the directory entry contains the file type, the third
field is filled in from that information.
On systems without the file type information, the extension falls back
to calling the stat() system call
in order to provide the information.
Thus the third field should never be ‘u’ (for “unknown”).
Normally, when reading directories, you should set FS
equal to "/". However, you may instead chose to create
PROCINFO["readdir_override"] (with any value). If this element
exists when the directory is opened, then the extension automatically
sets the fields in each record for you.
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.
Here is an example:
@load "readdir"
...
BEGIN { FS = "/" }
{ print "file name is", $2 }