Akhthar Parvez K wrote:
Hi all,
Hello,
I have been trying to get the mode of a directory with the stat
function in perl (currently using the one from File::stat) with no
success so far.
It looks like it is working to me.
Basically I want to check if a given directory is
having 1777 permission (like /tmp) and I was thinking about storing
the mode of the directory in a variable and check that variable for
the value 1777.
In Perl 1777 is a decimal value but you want the octal value 01777
instead (for example: $mode == 01777). Perl internally converts the
octal representation of 01777 to the decimal number 1023:
$ perl -le'print 01777'
1023
With this setup, however I'm unable to get the actual octal mode of
the directory stored into the variable.
That is because perl only deals with decimal numbers. To convert the
decimal number to its octal representation you have to use
printf/sprintf (as you have done below.)
I'm getting a weird value and
I can print the actual value by masking off the type using printf
"%40o", but here I don't have to print the perm, want to get it to use
it in an if condition.
The "weird value" is the actual value and the "actual value" is just the
octal representation of the actual decimal value.
#!/usr/bin/perl
use File::stat;
my $dir=$ARGV[0];
$st = stat($dir) or die "No $dir: $!";
my $stat_mode = $st->mode;
my $mode = $stat_mode & 07777;
print "stat_mode: $stat_mode\tmode: $mode\n";
printf "Actual value:%04o\n",$mode;
But, as you know, $mode is not storing the actual mode value.
Yes it is. It is just storing it as a decimal number and not as its
octal representation.
If the
actual mode of the directory is 0755, the following is the output:
stat_mode: 16877 mode: 493
Actual value:0755
Could anyone tell me how can I check if the given directory is having
1777 perm mode?
$ perl -le'
my $mode = ( stat "/tmp" )[ 2 ] & 07777;
print "/tmp mode is ", $mode == 01777 ? "" : "NOT ", "equal to 01777"
'
/tmp mode is equal to 01777
$ perl -le'
my $mode = ( stat "/usr" )[ 2 ] & 07777;
print "/usr mode is ", $mode == 01777 ? "" : "NOT ", "equal to 01777"
'
/usr mode is NOT equal to 01777
If you are on *nix then check the man page for the different values that
mode can contain:
man 2 stat
[ SNIP ]
The following flags are defined for the st_mode field:
S_IFMT 0170000 bit mask for the file type bit fields
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
John
--
The programmer is fighting against the two most
destructive forces in the universe: entropy and
human stupidity. -- Damian Conway
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