can we remove a directory from within that directory??
[input][input][input][input] Hi, I'm using Redhat 9 (kernel 2.4.20-8 on i686) I logged in as k(username), then I started terminal, & then I gave following commands:- k>pwd /home/k k>mkdir my_dir // i created a directory: my_dir k>cd my_dir // let's go in my_dir // now let's try to remove my_dir k>rmdir /home/k/my_dir // no error; k>ls /home/k/ // my_dir gone k>pwd /home/k/my_dir // oops!! // let's create my_file here!! k>cat >my_file bash: my_file: no such file or directory // I'm not allowed to a create file here. pwd says I'm in my_dir, but my_dir doesn't exist. I think: user should not be allowed to remove a directory, until & unless he is placed in a directory which is hierarchically above the one he has chosen to remove. If my approach is not right, I'd like to know the philosophy behind this. Happy contributing to LINUX!! kuldeep vyas - Yahoo! FareChase - Search multiple travel sites in one click. ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
Re: can we remove a directory from within that directory??
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 According to kuldeep vyas on 11/21/2005 4:42 AM: > Hi, > > I'm using Redhat 9 (kernel 2.4.20-8 on i686) > I logged in as k(username), then I started terminal, & > then I gave following commands:- > > k>pwd > /home/k > > k>mkdir my_dir > // i created a directory: my_dir > > k>cd my_dir > // let's go in my_dir > > > // now let's try to remove my_dir > k>rmdir /home/k/my_dir > // no error; ... > pwd says I'm in my_dir, but my_dir doesn't exist. > I think: user should not be allowed to remove a directory, > until & unless he is placed in a directory which is > hierarchically above the one he has chosen to remove. POSIX allows this behavior, but does not require it. Basically, on systems where it is legal to remove a directory that is in use, such as on Linux, the directory continues to exist until all references to it (such as processes that have it as the current working directory) have closed their file descriptors, even though the directory is no longer accessible from the file system. On other platforms, such as cygwin, where removing an in-use directory is forbidden by the OS, rmdir faithfully returns the error 'Device or resource busy'. It is a feature of Linux, and not a bug in coreutils, that rmdir on Linux can remove an in-use directory; and coreutils is just happy to provide the exact capabilities of the underlying system in this case. > > If my approach is not right, I'd like to know the > philosophy behind this. You are welcome to try and patch the Linux kernel to have rmdir fail with EBUSY if the directory is in use, but you will probably find that this increases the complexity of the kernel and would be a tough sell to the kernel crowd. - -- Life is short - so eat dessert first! Eric Blake [EMAIL PROTECTED] -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (Cygwin) Comment: Public key at home.comcast.net/~ericblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDgc/W84KuGfSFAYARAiIbAKCX/2SzbsWHbB/3DDBnQZGiVio/0wCfSQ4q 9Pw6xoNu9gBiM3o1shwxJRU= =GbPm -END PGP SIGNATURE- ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
Re: can we remove a directory from within that directory??
kuldeep vyas <[EMAIL PROTECTED]> writes: > k>pwd > /home/k/my_dir > // oops!! Try /bin/pwd. > pwd says I'm in my_dir, but my_dir doesn't exist. It does, it just doesn't have a name any more. > I think: user should not be allowed to remove a directory, > until & unless he is placed in a directory which is > hierarchically above the one he has chosen to remove. There is nothing wrong with unlinking a file (of any type) that is still in use. Andreas. -- Andreas Schwab, SuSE Labs, [EMAIL PROTECTED] SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
Re: can we remove a directory from within that directory??
It is a general design philosophy of linux, and unix in general, that the kernel will not enforce locking of files. This is why you can upgrade software without rebooting: the old file can be deleted and replaced with the new file, even though it is still in use. Of course, it isn't actually deleted until everyone using it closes it, but it's name is removed from the directory tree immediately. If you really want to mess up a system, you can rm -fr / ( as root of course ) and it will happily delete all the files on the system. Whatever is running at the time will keep running, but new opens will fail. This behavior is pretty much by design. kuldeep vyas wrote: [input][input][input][input] Hi, I'm using Redhat 9 (kernel 2.4.20-8 on i686) I logged in as k(username), then I started terminal, & then I gave following commands:- k>pwd /home/k k>mkdir my_dir // i created a directory: my_dir k>cd my_dir // let's go in my_dir // now let's try to remove my_dir k>rmdir /home/k/my_dir // no error; k>ls /home/k/ // my_dir gone k>pwd /home/k/my_dir // oops!! // let's create my_file here!! k>cat >my_file bash: my_file: no such file or directory // I'm not allowed to a create file here. pwd says I'm in my_dir, but my_dir doesn't exist. I think: user should not be allowed to remove a directory, until & unless he is placed in a directory which is hierarchically above the one he has chosen to remove. If my approach is not right, I'd like to know the philosophy behind this. Happy contributing to LINUX!! kuldeep vyas ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
Re: can we remove a directory from within that directory??
On Mon, 21 Nov 2005, kuldeep vyas wrote: I'm using Redhat 9 (kernel 2.4.20-8 on i686) I logged in as k(username), then I started terminal, & then I gave following commands:- [snip] k>ls /home/k/ // my_dir gone k>pwd /home/k/my_dir // oops!! It's likely here that "pwd" is the shell's builtin version, rather than coreutils'. Here what I see when calling /bin/pwd explicitly: $ rmdir -v $(/bin/pwd) rmdir: removing directory, /tmp/not-here $ /bin/pwd /bin/pwd: cannot get current directory: No such file or directory I'd agree that this discrepancy between shell builtin and coreutil is somewhat confusing. Cheers, Phil ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
Re: can we remove a directory from within that directory??
Hi Phillip, Thanks for information. While upgrading software (without reboot): this design technique is really good. But I've a doubt:- When we purchase License of a software/tool, after expiry date: License Files 1. are deleted, OR 2. are modified so that they can't be used further, OR 3. use date & time of the computer(on which they are running) to get expired, et al. Some softwares & tools can still be used even after expiry date, because they had started running before expiry date & never closed & hence still running even after expiry date. License files which are in the directory tree: come into picture when software/tool is started. Most of the softwares & tools are robust enough in design to handle this but some are still vulnerable. I wonder whether Operating System provides some option to ensure that: a file which is modified in the directory-tree must be accordingly & instantly updated in all forms of memory(RAM, cache etc.) I mean whatever is running in the system should not be keep on running once it's modified to stop & we shouldn't have to wait for next open. Happy contributing to LINUX!! kuldeep vyas Phillip Susi <[EMAIL PROTECTED]> wrote: It is a general design philosophy of linux, and unix in general, that the kernel will not enforce locking of files. This is why you can upgrade software without rebooting: the old file can be deleted and replaced with the new file, even though it is still in use. Of course, it isn't actually deleted until everyone using it closes it, but it's name is removed from the directory tree immediately. If you really want to mess up a system, you can rm -fr / ( as root of course ) and it will happily delete all the files on the system. Whatever is running at the time will keep running, but new opens will fail. This behavior is pretty much by design. kuldeep vyas wrote: > Hi, > > I'm using Redhat 9 (kernel 2.4.20-8 on i686) > I logged in as k(username), then I started terminal, & > then I gave following commands:- > > k>pwd > /home/k > > k>mkdir my_dir > // i created a directory: my_dir > > k>cd my_dir > // let's go in my_dir > > > // now let's try to remove my_dir > k>rmdir /home/k/my_dir > // no error; > > k>ls /home/k/ > // my_dir gone > > k>pwd > /home/k/my_dir > // oops!! > > // let's create my_file here!! > k>cat >my_file > bash: my_file: no such file or directory > // I'm not allowed to a create file here. > > > pwd says I'm in my_dir, but my_dir doesn't exist. > I think: user should not be allowed to remove a directory, > until & unless he is placed in a directory which is > hierarchically above the one he has chosen to remove. > > If my approach is not right, I'd like to know the > philosophy behind this. > > Happy contributing to LINUX!! > > kuldeep vyas > > > - Yahoo! FareChase - Search multiple travel sites in one click. ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
Re: can we remove a directory from within that directory??
On Mon, Nov 21, 2005 at 10:45:08PM -0800, kuldeep vyas wrote: > I wonder whether Operating System provides some option to ensure that: > a file which is modified in the directory-tree must be accordingly & > instantly updated in all forms of memory(RAM, cache etc.) > I mean whatever is running in the system should not be keep on running > once it's modified to stop & we shouldn't have to wait for next open. This is a question about your operating system, not coreutils. It's off-topic for this list, really. With traditional Unix semantics, I/O against a file gives consistent results across all processes (on the same machine) which have it open, even if it is 'deleted'. In Unix, the only meaning of the 'unlink' system call is to reduce the link count of a file by one. That's it. It does nothing else. There is no separate 'delete' system call. Once the link count of a file reaches zero, it can no longer be opened (because it no longer has a name, no possible argument to the open(2) system call can select it) but processes that already have it open can continue to use it. When a file is closed and no other processes have the file open, and the current link count of the file is zero, the inode and data blocks of the file's data are reclaimed. I've tried to be clear here, but this is not really the place for long explanations of how Unix works. If you are still in need of further information here, I would suggest that you read the book "Advanced Programming in the Unix Environment" by W. Richard Stevens. Regards, James. ___ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils
