libtrash - a shared library to implement a "recycle bin" -------- or "trash can" under GNU/Linux. Written by Manuel Arriaga (m.arriaga@ip.pt). Copyright (C) 2001 Manuel Arriaga Licensed under the GNU General Public License version 2. See the file COPYING for details. Version: 0.2 (2001-08-11) ------- See CHANGE.LOG for details. DESCRIPTION: ----------- libtrash is a shared library which, when preloaded, will intercept calls to glibc's unlink() and make sure that the specified file won't be permanently removed but rather moved to a "trash can". It also allows the super user to mark certain directories as "unremovable", which means that requests to unlink files under them will always fail, even if they were issued by root. (This last feature is meant as a higher-level substitute for ext2fs' "immutable" flag for use by those of us who rely on other file systems.) A companion script called hardrm is also provided; it simply passes along its arguments to the program rm after having temporarily suspended libtrash, which results in the _effective_ deletion of those files. I suggest that you don't even put it in your path, otherwise you might get used to using it instead of the "usual" rm, and then there won't be anything libtrash will be able to do for you if you let your fingers slip. If, at the command line, you need to issue one command with libtrash disabled, just prepend it with LD_PRELOAD="" E.g., to permanently remove remove the file "test.txt" while libtrash is active, you could either invoke hardrm or type LD_PRELOAD="" rm test.txt (This is how hardrm works.) An alternative to this method is mentioned below. libtrash works with any GNU/Linux program which calls glibc's unlink() when it needs to remove a file; therefore, it works seamlessly at the console and under XFree86, independently of the programming language the program was written in (unless, of course, it uses its own, low-level, deletion routine). INSTALLATION: ------------ To configure: 1 - Edit the Makefile if you wish to change the directory in which the library will be stored (default: /usr/local/lib). 2 - Edit the section marked "Configuration" near the top of libtrash.c. All compile-time options are verbosely explained there. To compile: 3 - Run "make". To install: 4 - Run, as root, "make install". This copies libtrash-0.2 to the directory specified at the top of the Makefile and runs ldconfig. hardrm isn't installed by default. To activate libtrash: 5 - So that calls to unlink() are intercepted, you must "preload" this library. This is done by running the following command whenever you log in: export LD_PRELOAD=path_of_symlink_to_libtrash where path_of_symlink_to_libtrash should be substituted with the real path to that symbolic link (if you didn't modify the INSTLIBDIR variable in the Makefile, that would be "/usr/local/lib/libtrash.so.0"). This can be achieved in a painless way by appending that line to a file which gets executed whenever you log in, such as ~/.profile or ~/.bash_login. If you wish to activate libtrash for every user on the system, append that line to /etc/profile instead. (Note: Your distribution might use different files for this purpose. If you use a shell other than Bash, you probably know what to do in your situation.) ---------- libtrash should now be set up and ready to spare you a lot of headaches. You can test drive it with the following commands (assuming that you didn't change TRASH_CAN to a string other than "Trash"): $ touch test_file $ rm test_file $ ls Trash/ test_file should now be stored in Trash/. But don't be fooled by this example! libtrash isn't restricted to "saving" files which you explicitly deleted with "rm": it also works with your (graphical) file manager, mail user agent, etc... SUSPENDING/RESUMING libtrash: ---------------------------- Should you need to temporarily disable libtrash, you do so by running the command unset LD_PRELOAD When you are done, libtrash can be reactivated by typing: export LD_PRELOAD=path_of_symlink_to_libtrash You might make these operations simpler by appending the following two lines to the init file you used in step 5) above (if you are using Bash as your shell): alias trash_on="export LD_PRELOAD=path_of_symlink_to_libtrash" alias trash_off="unset LD_PRELOAD" After doing so, you can enable/disable libtrash by typing trash_on or trash_off at the prompt. CONTACT: ------- This library was written by me, Manuel Arriaga. Feel free to contact me at m.arriaga@ip.pt with questions, suggestions or bug reports. CREDITS: ------- - Avery Pennarun (apenwarr@foxnet.net), whose "freestyle-concept" tarball showed me how to intercept system calls and write a suitable Makefile.
