Manual Reference Pages - STAT::LSMODE (3)
Stat::lsMode - format file modes like the "ls -l" command does
$mode = (stat $file);
$permissions = format_mode($mode);
# $permissions is now something like `drwxr-xr-x
$permissions = file_mode($file); # Same as above
$permissions = format_perms(0644); # Produces just rw-r--r--
$permissions = format_perms(644); # This generates a warning message:
# mode 644 is very surprising. Perhaps you meant 0644...
Stat::lsMode->novice(0); # Disable warning messages
Stat::lsMode generates mode and permission strings that look like
the ones generated by the Unix ls -l command. For example, a
regular file that is readable by everyone and writable only by its
owner has the mode string -rw-r--r--. Stat::lsMode will either
examine the file and produce the right mode string for you, or you can
pass it the mode that you get back from Perls stat call.
Given a mode number (such as the third element of the list returned by
stat), return the appopriate ten-character mode string as it would
have been generated by ls -l. For example,
consider a directory that is readable and searchable by everyone, and
also writable by its owner. Such a directory will have mode 040755.
When passed this value, format_mode will return the string
If format_mode is passed a permission number like 0755, it will
return a nine-character string insted, with no leading character to
say what the file type is. For example, format_mode(0755) will
return just rwxr-xr-x, without the leading d.
Given a filename, do lstat on the file to determine the mode, and
return the mode, formatted as above.
Novice Operation Mode
A common mistake when dealing with permission modes is to use 644
where you meant to use 0644. Every permission has a numeric
representation, but the representation only makes sense when you write
the number in octal. The decimal number 644 corresponds to a
permission setting, but not the one you think. If you write it in
octal you get 01204, which corresponds to the unlikely permissions
-w----r-T, not to rw-r--r--.
The appearance of the bizarre permission -w----r-T in a program is
almost a sure sign that someone used 644 when they meant to use
0644. By default, this module will detect the use of such unlikely
permissions and issue a warning if you try to format them. To disable
these warnings, use
Stat::lsMode->novice(0); # disable novice mode
Stat::lsMode->novice(1); # enable novice mode again
The surprising permissions that are diagnosed by this mode are:
111 => --xr-xrwx
400 => rw--w----
440 => rw-rwx---
444 => rw-rwxr--
551 => ---r--rwt
600 => --x-wx--T
640 => -w------T
644 => -w----r-T
660 => -w--w-r-T
664 => -w--wx--T
666 => -w--wx-wT
700 => -w-rwxr-T
711 => -wx---rwt
750 => -wxr-xrwT
751 => -wxr-xrwt
751 => -wxr-xrwt
755 => -wxrw--wt
770 => r------wT
771 => r------wt
775 => r-----rwt
777 => r----x--t
Of these, only 400 is remotely plausible.
As far as I know, the precise definition of the mode bits is portable
between varieties of Unix. The module should, however, examine
stat.h or use some other method to find out if there are any local
variations, because Unix being Unix, someone somewhere probably does
Maybe it file_mode should have an option that says that if the file
is a symlink, to format the mode of the pointed to file instead of the
mode of the link itself, the way ls -Ll does.
Mark-Jason Dominus (email@example.com).
|perl v5.20.3 ||LSMODE (3) ||1998-04-20 |
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