# Changing permission on a file **URL:** \ **Category:** Ruby\ **Created:** [November 17, 2006, 2:19am UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261 "2006-11-17T02:19:00Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![apparna](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@apparna](https://www.ruby-forum.com/u/apparna)\ **Post date:** [November 17, 2006, 2:19am UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261/1 "2006-11-17T02:19:00Z")
I’m trying to change permission on a file on a windows machine. This should work according to the documentation (may be i’m missing something here). But it doesn’t here is the code: # take away read permission new\_permission = File.lstat(“testfile”).mode ^ 0004 File.chmod(new\_permission, “testfile” ) File.readable?(“testfile”) #=\> true or new\_permission = File.lstat(“testfile”).mode ^ File::O\_R File.chmod(new\_permission, “testfile” ) What am I doing wrong? Thanks Apparna ---
**Author:** ![apparna](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@apparna](https://www.ruby-forum.com/u/apparna)\ **Post date:** [November 17, 2006, 6:21am UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261/2 "2006-11-17T06:21:08Z")
App Ra wrote: > I’m trying to change permission on a file on a windows machine. This > should work according to the documentation (may be i’m missing something > here). But it doesn’t Be specific. What did you expect, and what did you get instead? Any error messages? > here is the code: > > # take away read permission > > new\_permission = File.lstat(“testfile”).mode ^ 0004 Hoo-boy. Do you know what “^” actually does? Do it this way: x & 4 ^ 0xffff Meaning original value “AND” the bit-flip of the desired pattern. That way, you actually get a predictable result, regardless of the original value, instead of an unpredictable toggle. > File.chmod(new\_permission, “testfile” ) > File.readable?(“testfile”) #=\> true > > or > > new\_permission = File.lstat(“testfile”).mode ^ File::O\_R Again, think about what “^” does, and which input arguments produce which output arguments. > File.chmod(new\_permission, “testfile” ) > > What am I doing wrong? Also, be sure to say what happened, how you know something is wrong. ---
**Author:** ![apparna](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@apparna](https://www.ruby-forum.com/u/apparna)\ **Post date:** [November 17, 2006, 6:37am UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261/3 "2006-11-17T06:37:11Z")
Paul L. wrote: > > # take away read permission > > > > new\_permission = File.lstat(“testfile”).mode ^ 0004 > > Hoo-boy. Do you know what “^” actually does? Do it this way: > > x & 4 ^ 0xffff > > Meaning original value “AND” the bit-flip of the desired pattern. That > way, you actually get a predictable result, regardless of the original > value, instead of an unpredictable toggle. Let me add, for clarity, to SET bit 2 (starting at 0 = LSB): x |= 4 to CLEAR bit 2: x &= 4 ^ 0xffff The idea is to act only on the chosen bit and have no effect on any other bits. ---
**Author:** ![apparna](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@apparna](https://www.ruby-forum.com/u/apparna)\ **Post date:** [November 17, 2006, 9:37am UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261/4 "2006-11-17T09:37:25Z")
App Ra schrieb: > I’m trying to change permission on a file on a windows machine. The documentation of File.chmod says “Actual effects are platform dependent”. Does Windows support taking away read permissions? How would you do this in Windows? Regards, Pit ---
**Author:** ![apparna](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@apparna](https://www.ruby-forum.com/u/apparna)\ **Post date:** [November 17, 2006, 12:01pm UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261/5 "2006-11-17T12:01:39Z")
In Windows there is no read permission , may be you can try to set it as hidden , read permission is in \*nix only On 11/17/06, Pit C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > – Chỉ có lý trí của bản thân má»›i soi sáng được sá»± thật.“Cái đẹp đẽ nhất mà chúng ta có thể trải nghiệm được là cái bí ẩn. Đó là cảm thức nền tảng trong cái nôi của nghệ thuật và khoa học chân chính. Kẻ nà o không biết đến nó, không còn khả năng ngạc nhiên hay kinh ngạc, kẻ đó coi nhÆ° đã chết, đã tắt rụi lá»­a sống trong mắt mình”“Das Schönste, was wir erleben können, ist das Geheimnisvolle. Es ist das Grundgefühl, das an der Wiege von wahrer Kunst und Wissenschaft steht. Wer es nicht kennt und sich nicht mehr wundern, nicht mehr staunen kann, der ist sozusagen tot und sein Auge erloschen.”“The fairest thing we can experience is the mysterious. It is the fundamental emotion which stands at the cradle of true art and true science. He who knows it not and can no longer wonder, no longer feel amazement, is as good as dead, his eyelight has been extinct.” ---
**Author:** ![apparna](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@apparna](https://www.ruby-forum.com/u/apparna)\ **Post date:** [November 17, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/changing-permission-on-a-file/76261/6 "2006-11-17T14:46:07Z")
App Ra wrote: > I’m trying to change permission on a file on a windows machine. This > should work according to the documentation (may be i’m missing something > here). But it doesn’t > here is the code: > > # take away read permission > > new\_permission = File.lstat(“testfile”).mode ^ 0004 > File.chmod(new\_permission, “testfile” ) > File.readable?(“testfile”) #=\> true Windows only supports two modes for File.chmod - 0644 (read/write) or 0444 (readonly). You can use advanced attribute and security settings with the win32-file package. However, you cannot make a file unreadable on Windows except perhaps through ACL. Regards, Dan PS - File.lstat is the same as File.stat on Windows.