use strict;
use warnings;

my $newFile = q{spw585219.txt};
my $newFH;

open $newFH, q{>}, $newFile
   or die qq{open: $newFile: $!\n};
close $newFH
   or die qq{close: $newFile: $!\n};

my $ls = `/usr/bin/ls -l $newFile`;
print $ls;

chmod 0777, $newFile
   or die qq{chmod: $newFile: $!\n};

$ls = `/usr/bin/ls -l $newFile`;
print $ls;

open $newFH, q{>}, $newFile
   or die qq{open: $newFile: $!\n};

print $newFH qq{The quick brown fox etc\n};

close $newFH
   or die qq{close: $newFile: $!\n};

$ls = `/usr/bin/ls -l $newFile`;
print $ls;
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and here is the output showing the ls -l results

-rw-r--r--   1 johngg   staff          0 Nov 21 10:29 spw585219.txt
-rwxrwxrwx   1 johngg   staff          0 Nov 21 10:29 spw585219.txt
-rwxrwxrwx   1 johngg   staff         24 Nov 21 10:29 spw585219.txt
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I hope this is of use.

Cheers,

JohnGG

sysopen(FILEHANDLE, $filename, permissions, CHMOD);
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#!/usr/bin/perl
use strict;
use Fcntl;

my $var = 1;

while ($var) {
    sysopen (FILE, '/home/smaug/testing/file.txt', O_RDWR|O_EXCL|O_CRE
+AT, 0777);
    printf FILE "A value of n\n";
}
close (FILE);
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That's still going to be affected by umask, and is unlikely to reliably give 777 as the permission mode of the file.

You're probably best off creating the file first with your specific requirements, then opening it.

---
my name's not Keith, and I'm not reasonable.

Agreed, but you're also unlikely to want a file that is open for writing to be executed.

On my OS (Ubuntu Linux) the OS prevents writing to files that are already open for writing,

That's a very odd Unix. One I've never encountered before.

Now, there are some OSses that won't allow you to write to pages binaries currently being executed by some process (giving you a 'text busy' message), but that's something else entirely.

(The same is shown by trying to open the same file twice using "vi".)

Ah, yes, that editor. The one that tries to be vi but isn't. I'm a vi-lover and have been using vi and vi-clones for 25+ years. But I loathe environments where 'vi file' starts up an editor that isn't quite 'vi'. By all means, if you call it 'vi', then have it act like 'vi'. If it acts otherwise, call it otherwise.

As for that editor, that editor creates another file in the same directory, and if that file exists, it thinks the file is already edited and starts complaining. That has nothing to do with the OS - that's just a behavioural thing of the editor that isn't quite vi. Using another program, I can happily modify the same file.

Thanks for that, although it really did not help me.
Thanks johngg.

#!/usr/bin/perl

use strict;
use warnings;
use Fcntl;

my $FILE = 'foobarbaz';

umask 0;
-e $FILE && unlink $FILE;
sysopen my $fh, $FILE, O_CREAT, 0777 or die "$!";
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I don't think it's possible to do this with open in an atomic manner (please correct me if I'm wrong). open has a built-in mask of 0666. Just open the file normally and chmod it immediately afterwards.

Thanks Monks,

        Your suggestions are very usefull for me.

thanks,
Perl User.
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I'd never do that myself. If I really want to create a file with 0777 permissions, I'd use chmod() after finishing writing the file.