Re: Reg. Directory listing program

Gunwant Singh wrote:
> Hi,

Hello,

> Let me thank you for your help. I think you guys are doing a great work, its
> really appreciative.
> Thanks to David and John. Now that I changed my *"perl"* code to the
> following, its actually working!!!!
> 
> *use strict;
> use warnings;
> use File::stat;
> 
> opendir (DH, "subcode") or die "$!";
> chdir("C:/Documents and Settings/Myself/Desktop/code/subcode");
> 
> foreach my $file(readdir DH)
> {
> my $value=stat($file);
> my $perm=$value->mode & 07777;
> printf "\n$file\t%04o\n", $perm;
> }
> 
> closedir (DH);*
> 
> 
> Leading to a question, why did we 'AND' *mode* to *07777*. What does each
> bit stand for and why there  are 5 bits as compared to UNIX's
> User-Group-Others bits. So actually 3 questions :)

man 2 stat
[snip]
        The following flags are defined for the st_mode field:

               S_IFMT     0170000   bitmask for the file type bitfields
               S_IFSOCK   0140000   socket
               S_IFLNK    0120000   symbolic link
               S_IFREG    0100000   regular file
               S_IFBLK    0060000   block device
               S_IFDIR    0040000   directory
               S_IFCHR    0020000   character device
               S_IFIFO    0010000   FIFO
               S_ISUID    0004000   set UID bit
               S_ISGID    0002000   set-group-ID bit (see below)
               S_ISVTX    0001000   sticky bit (see below)
               S_IRWXU    00700     mask for file owner permissions
               S_IRUSR    00400     owner has read permission
               S_IWUSR    00200     owner has write permission
               S_IXUSR    00100     owner has execute permission
               S_IRWXG    00070     mask for group permissions
               S_IRGRP    00040     group has read permission
               S_IWGRP    00020     group has write permission
               S_IXGRP    00010     group has execute permission
               S_IRWXO    00007     mask for permissions for others (not 
in group)
               S_IROTH    00004     others have read permission
               S_IWOTH    00002     others have write permission
               S_IXOTH    00001     others have execute permission


So "mode & 07777" displays the permission bits as well as SUID, SGID and 
the "sticky" bit.



John
-- 
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order.                            -- Larry Wall