Format file modes like the \*(c`ls -l\*(c' command does
use Stat::lsMode; $mode = (stat $file)[2]; $permissions = format_mode($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
\*(C`Stat::lsMode\*(C' generates mode and permission strings that look like the ones generated by the Unix \*(C`ls -l\*(C' command. For example, a regular file that is readable by everyone and writable only by its owner has the mode string \*(C`-rw-r--r--\*(C'. \*(C`Stat::lsMode\*(C' 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 Perl's \*(C`stat\*(C' call. Given a mode number (such as the third element of the list returned by \*(C`stat\*(C'), return the appopriate ten-character mode string as it would have been generated by \*(C`ls -l\*(C'. 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, \*(C`format_mode\*(C' will return the string \*(C`drwxr-xr-x\*(C'.
If \*(C`format_mode\*(C' 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, \*(C`format_mode(0755)\*(C' will return just \*(C`rwxr-xr-x\*(C', without the leading \*(C`d\*(C'. Given a filename, do \*(C`lstat\*(C' on the file to determine the mode, and return the mode, formatted as above.
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 \*(C`-w----r-T\*(C', not to \*(C`rw-r--r--\*(C'.
The appearance of the bizarre permission \*(C`-w----r-T\*(C' 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 \*(C`stat.h\*(C' or use some other method to find out if there are any local variations, because Unix being Unix, someone somewhere probably does it differently.
Maybe it \*(C`file_mode\*(C' 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 \*(C`ls -Ll\*(C' does.
\*(C`http://www.plover.com/~mjd/perl/lsMode/\*(C'.
ls
chmod
stat
Mark-Jason Dominus (\*(C`[email protected]\*(C').