There are several options here. Pretty much any way you
go about it, you'll need to get the existing file's
permissions from stat, mentioned above. Setting your umask
to those permissions is one way to go about it, but a umask
is only a mask applied to newly created files, not an
absolute setting of permissions. To set permissions, you
could create the file first, then use chmod. Or you
could use the built-in POSIX module and its creat() and
open() modules, in which case you'd be working with file
descriptors instead of file handles. The best way I can
see, though, is through something like:
use POSIX;
my $perms = (stat "file")[2];
sysopen(OUT, "newfile", O_CREAT | O_WRONLY, $perms) or die "$!\n";
print OUT "whatever\n";
close(OUT);
This lets you create a file with given permissions, and work
with filehandles. The O_CREAT is needed to create the file
if it doesn't already exist, and the O_WRONLY is needed to
write to the file in case it doesn't have write perms
(don't worry, if the file doesn't have write perms,
O_WRONLY won't affect that. It'll write to the file and
leave the perms untouched). | [reply]
[d/l] |
Why not use umask? The only other built-in way I know of that might be of use is perldoc -f -X, but I'm not sure that's what you want.
You might look at Stat::lsMode from CPAN if you would rather deal with permissions as -rwxr-xr-x (as ls -l would show you). | [reply] |
I'm not sure that I do want umask:
To clarify, the mode I need the files created with is unknown.
What I'm trying to do is to check the mode of a file that already exists, and then create other files that have the same mode (i.e., I don't know what mode the files need to be created with yet).
So my logic would possibly go something like:
1) get mode of file1;
2) create files file2, file3,..., fileN;
3) chmod files file2,..., fileN to the same mode as file1.
If that makes any more sense... | [reply]
[d/l] |
You could do that, sure... in that case you just need to
use stat to get the mode of the file.
my $mode = (stat "foo")[2];
But I think you could use umask, still... and it may make
it easier. Try something like this:
my $mode = (stat "foo")[2];
my $mask = 777 -
join '', (($mode&0700)>>6, ($mode&0070)>>3, ($mode&0007));
umask oct $mask;
I'm not sure if this is absolutely right (please someone
correct me if it isn't), but it seemed to work for the test
cases I tried. | [reply]
[d/l]
[select] |
You want umask.
To *get* the permissions of a file, I assume you'd want to
use stat, yes, or File::stat, which gives a nice by-name
interface to the stat fields. So, for example,
use File::stat;
my $st = stat "foo";
print "file is executable" if $st->mode & 0111;
I'm not quite sure how you'd go about turning file
permissions into a file creation mask (as used by
umask), other than a big if/then block. | [reply]
[d/l] |