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23 years ago
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# |
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# |
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# Stat::lsMode |
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# |
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# Copyright 1998 M-J. Dominus |
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# (mjd-perl-lsmode-id-i0k+gzzokd+@plover.com) |
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# |
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# You may distribute this module under the same terms as Perl itself. |
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# |
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# $Revision: 1.1 $ $Date: 2000/12/23 07:42:57 $ |
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package BootRoot::lsMode; |
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$VERSION = '0.50'; |
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use Carp; |
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use Exporter; |
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@ISA = qw(Exporter); |
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@EXPORT = qw(format_mode file_mode format_perms lsmode); |
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@perms = qw(--- --x -w- -wx r-- r-x rw- rwx); |
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%smerp = map {$perms[$_] => $_} (0 .. $#perms); |
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@ftype = ('', qw(p c ? d ? b ? - ? l ? s ? ? ?)); |
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%typef = map {$ftype[$_] => $_} (0 .. $#ftype); |
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$NOVICE_MODE = 1; # Default on? |
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sub novice { |
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my $pack = shift; |
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croak "novice_mode requires one boolean argument" unless @_ == 1; |
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my $old = $NOVICE_MODE; # Should this be localized t $pack? |
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$NOVICE_MODE = $_[0]; |
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$old; |
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} |
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sub format_mode { |
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croak "format_mode requires a mode as an argument" unless @_ >= 1; |
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my $mode = shift; |
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my %opts = @_; |
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unless (defined $mode) { |
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return wantarray() ? () : undef; |
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} |
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_novice_warning($mode) if $NOVICE_MODE; |
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my $setids = ($mode & 07000)>>9; |
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my @permstrs = @perms[($mode&0700)>>6, ($mode&0070)>>3, $mode&0007]; |
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my $ftype = $ftype[($mode & 0170000)>>12]; |
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my @ftype = $opts{no_ftype} ? () : ($ftype); |
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if ($setids) { |
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if ($setids & 01) { # Sticky bit |
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$permstrs[2] =~ s/([-x])$/$1 eq 'x' ? 't' : 'T'/e; |
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} |
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if ($setids & 04) { # Setuid bit |
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$permstrs[0] =~ s/([-x])$/$1 eq 'x' ? 's' : 'S'/e; |
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} |
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if ($setids & 02) { # Setgid bit |
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# Maybe substr($permstrs[1], -1) =~ tr/-x/Ss/; instead. LOD! |
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$permstrs[1] =~ s/([-x])$/$1 eq 'x' ? 's' : 'S'/e; |
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} |
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} |
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if (wantarray) { |
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(@ftype, @permstrs); |
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} else { |
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join '', @ftype, @permstrs; |
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} |
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} |
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sub file_mode { |
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croak "file_mode requires one filename as an argument" unless @_ == 1; |
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my $file = shift; |
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my $mode = (lstat $file)[2]; |
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unless (defined $mode) { |
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if (wantarray) { |
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return (); |
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} else { |
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carp "Couldn't get mode for file `$file': $!" if $NOVICE_MODE; |
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return undef; |
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} |
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} |
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format_mode($mode, @_); |
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} |
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# This was suggested by Colin Kuskie |
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sub lsmode { |
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my $lsmode = shift; |
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my ($t, $u, $g, $o); |
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my $ld; |
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if (length($lsmode) == 9) { |
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($u, $g, $o) = unpack "A3 A3 A3", $lsmode; |
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$ld = 0; |
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} elsif (length($lsmode) == 10) { |
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($t, $u, $g, $o) = unpack "A1 A3 A3 A3", $lsmode; |
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$ld = $typef{$t} |
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or croak("Mode `$lsmode' begins with unrecognized character `$t'"); |
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$ld = sprintf "%01o", $ld; |
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} else { |
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croak "Unrecognizable mode `$lsmode'"; |
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} |
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# Fix sticky bit? |
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if ($o =~ /s$/i) { |
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croak "Mode `$lsmode' may not end with `s'; aborting"; |
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} |
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my $octperm = ''; |
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my $setuid = 0; |
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foreach $perm ($u, $g, $o) { |
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# LOD |
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$setuid = $setuid * 2 + ($perm =~ s/([st])$/($1 eq lc $1)?'x':'-'/ie); |
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$octperm .= $smerp{$perm}; |
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} |
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my $perm = oct(sprintf "0$ld$setuid$octperm"); |
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$perm; |
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} |
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sub format_perms { |
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croak "format_perms requires a permission mode as an argument" unless @_ == 1; |
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format_mode($_[0], no_ftype => 1); |
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} |
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# None of these are really plausible modes. |
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# They are all almost certain to have occurred |
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# when someone used decimal instead of octal to specify a mode. |
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@badmodes = (777, 775, 755, 770, 700, 750, |
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751, |
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666, 664, 644, 660, 600, 640, |
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444, 440, |
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400, # 400 = rw--w---- which is just barely plausible. |
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# 000 *is* OK. It means just what you think. |
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711, 771, 751, 551, 111, |
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); |
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%badmode = map {($_ => 1)} @badmodes; |
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# Novices like to ask for the bits for mode `666' instead of `0666'. |
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# Try to detect and diagnose that. |
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sub _novice_warning { |
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my $mode = shift; |
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if ($badmode{$mode}) { |
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carp "mode $mode is very surprising. Perhaps you meant 0$mode"; |
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} |
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} |
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=head1 NAME |
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Stat::lsMode - format file modes like the C<ls -l> command does |
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=head1 SYNOPSIS |
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use Stat::lsMode; |
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$mode = (stat $file)[2]; |
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$permissions = format_mode($mode); |
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# $permissions is now something like `drwxr-xr-x' |
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$permissions = file_mode($file); # Same as above |
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$permissions = format_perms(0644); # Produces just 'rw-r--r--' |
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$permissions = format_perms(644); # This generates a warning message: |
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# mode 644 is very surprising. Perhaps you meant 0644... |
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Stat::lsMode->novice(0); # Disable warning messages |
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=head1 DESCRIPTION |
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C<Stat::lsMode> generates mode and permission strings that look like |
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the ones generated by the Unix C<ls -l> command. For example, a |
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regular file that is readable by everyone and writable only by its |
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owner has the mode string C<-rw-r--r-->. C<Stat::lsMode> will either |
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examine the file and produce the right mode string for you, or you can |
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pass it the mode that you get back from Perl's C<stat> call. |
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=head2 C<format_mode> |
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Given a mode number (such as the third element of the list returned by |
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C<stat>), return the appopriate ten-character mode string as it would |
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have been generated by C<ls -l>. For example, |
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consider a directory that is readable and searchable by everyone, and |
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also writable by its owner. Such a directory will have mode 040755. |
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When passed this value, C<format_mode> will return the string |
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C<drwxr-xr-x>. |
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If C<format_mode> is passed a permission number like C<0755>, it will |
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return a nine-character string insted, with no leading character to |
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say what the file type is. For example, C<format_mode(0755)> will |
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return just C<rwxr-xr-x>, without the leading C<d>. |
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=head2 C<file_mode> |
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Given a filename, do C<lstat> on the file to determine the mode, and |
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return the mode, formatted as above. |
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=head2 Novice Operation Mode |
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A common mistake when dealing with permission modes is to use C<644> |
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where you meant to use C<0644>. Every permission has a numeric |
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representation, but the representation only makes sense when you write |
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the number in octal. The decimal number 644 corresponds to a |
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permission setting, but not the one you think. If you write it in |
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octal you get 01204, which corresponds to the unlikely permissions |
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C<-w----r-T>, not to C<rw-r--r-->. |
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The appearance of the bizarre permission C<-w----r-T> in a program is |
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almost a sure sign that someone used C<644> when they meant to use |
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C<0644>. By default, this module will detect the use of such unlikely |
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permissions and issue a warning if you try to format them. To disable |
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these warnings, use |
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Stat::lsMode->novice(0); # disable novice mode |
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Stat::lsMode->novice(1); # enable novice mode again |
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The surprising permissions that are diagnosed by this mode are: |
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111 => --xr-xrwx |
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400 => rw--w---- |
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440 => rw-rwx--- |
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444 => rw-rwxr-- |
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551 => ---r--rwt |
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600 => --x-wx--T |
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640 => -w------T |
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644 => -w----r-T |
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660 => -w--w-r-T |
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664 => -w--wx--T |
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666 => -w--wx-wT |
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700 => -w-rwxr-T |
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711 => -wx---rwt |
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750 => -wxr-xrwT |
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751 => -wxr-xrwt |
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751 => -wxr-xrwt |
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755 => -wxrw--wt |
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770 => r------wT |
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771 => r------wt |
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775 => r-----rwt |
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777 => r----x--t |
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Of these, only 400 is remotely plausible. |
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=head1 BUGS |
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As far as I know, the precise definition of the mode bits is portable |
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between varieties of Unix. The module should, however, examine |
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C<stat.h> or use some other method to find out if there are any local |
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variations, because Unix being Unix, someone somewhere probably does |
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it differently. |
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Maybe C<file_mode> should have an option that says that if the file |
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is a symlink, to format the mode of the pointed to file instead of the |
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mode of the link itself, the way C<ls -Ll> does. |
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=head1 SEE ALSO |
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=over 4 |
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=item * |
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C<http://www.plover.com/~mjd/perl/lsMode/>. |
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=item * |
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L<ls> |
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=item * |
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L<chmod> |
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=item * |
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L<stat> |
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=back |
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=head1 AUTHOR |
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Mark-Jason Dominus (C<mjd-perl-lsmode-id-i0k+gzzokd+@plover.com>). |
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=cut |
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