linux下安全的执行rm

转载时请注明出处和作者联系方式
文章出处：http://blog.youkuaiyun.com/jack0106 
作者联系方式：冯牮 fengjian0106@yahoo.com.cn

 

前两天有个同事在命令行下面执行rm的时候，不小心删除了很多系统文件，搞得系统崩溃了，我们想过恢复ext4文件系统，但是没有成功，最终还是重装电脑。我之前也犯过同样的错误，所以再总结一下

 

1. 最简单的办法，将rm替换为mv，方法如下：

 

在~/.bashrc 文件里追加下面一段，然后刷新该文件 source ~/.bashrc 即可。使用rm命令的时候就会把文件移动到指定的文件夹~/.trash下 

 

mkdir -p ~/.trash alias rm=trash trash() { mv $@ ~/.trash/ }  

 

 

这种方法虽然简单，但是还不够灵活，而且这个rm命令，不能处理命令行选项。

 

2. 第一种方法的改进，可以参考此帖http://iregex.org/blog/safer-rm-command.html

不足的地方----仍然是不能处理rm的命令行选项。

 

3. 提供一个和rm兼容的工具，选项参数和rm保持一致。（这个代码我还没有找到，我也没有自己去写，因为，后面还有更好的方法）

不足的地方----本来这种方法已经没有不足了，但是，gnome图形环境下，是有回收站的，我们还可以更好的和回收站整合

 

4. 提供一个和rm兼容的工具，选项参数和rm保持一致，并且，文件会被删除到gnome的回收站中（gnome回收站的路径是~/.local/share/Trash  其中还包含2个或多个子路径，回收站里面不仅保存文件，还保存执行删除操作时的一起额外信息，比如原始路径和删除的时间），这样的话，在图形环境下，也可以察看被删除的文件，并且可以恢复。

 

 

这个工具已经有了，不需要我们自己造轮子，在ubuntu下执行sudo apt-get install trash-cli，然后就会得到trash这个命令行工具，看一下它的帮助信息，和容易就可以使用了

 

trash --help

Usage: trash [OPTION]... FILE...

 

Put files in trash

 

Options:

  --version            show program's version number and exit

  -h, --help           show this help message and exit

  -d, --directory      ignored (for GNU rm compatibility)

  -f, --force          ignored (for GNU rm compatibility)

  -i, --interactive    ignored (for GNU rm compatibility)

  -r, -R, --recursive  ignored (for GNU rm compatibility)

  -v, --verbose        explain what is being done

 

 

 

 

5. 如果要重新造轮子，怎么造？

这就要用到glib中的gio模块，在gio中，文件都是用GFile来表示的，GFile有一个函数，就是把文件删除到回收站中，函数如下：

gboolean g_file_trash (GFile *file, GCancellable *cancellable, GError **error); 

 

要自己造轮子，就要用到这个函数，还可以进一步深入，这个函数的内部，是如何实现的？这个函数的内部，调用到了glocalfile.c中的另外一个函数，如下：

static gboolean g_local_file_trash (GFile *file, GCancellable *cancellable, GError **error) { GLocalFile *local = G_LOCAL_FILE (file); GStatBuf file_stat, home_stat; const char *homedir; char *trashdir, *topdir, *infodir, *filesdir; char *basename, *trashname, *trashfile, *infoname, *infofile; char *original_name, *original_name_escaped; int i; char *data; gboolean is_homedir_trash; char delete_time[32]; int fd; GStatBuf trash_stat, global_stat; char *dirname, *globaldir; GVfsClass *class; GVfs *vfs; if (g_lstat (local->filename, &file_stat) != 0) { int errsv = errno; g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv), _("Error trashing file: %s"), g_strerror (errsv)); return FALSE; } homedir = g_get_home_dir (); g_stat (homedir, &home_stat); is_homedir_trash = FALSE; trashdir = NULL; if (file_stat.st_dev == home_stat.st_dev) { is_homedir_trash = TRUE; errno = 0; trashdir = g_build_filename (g_get_user_data_dir (), "Trash", NULL); if (g_mkdir_with_parents (trashdir, 0700) < 0) { char *display_name; int errsv = errno; display_name = g_filename_display_name (trashdir); g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv), _("Unable to create trash dir %s: %s"), display_name, g_strerror (errsv)); g_free (display_name); g_free (trashdir); return FALSE; } topdir = g_strdup (g_get_user_data_dir ()); } else { uid_t uid; char uid_str[32]; uid = geteuid (); g_snprintf (uid_str, sizeof (uid_str), "%lu", (unsigned long)uid); topdir = find_topdir_for (local->filename); if (topdir == NULL) { g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, _("Unable to find toplevel directory for trash")); return FALSE; } /* Try looking for global trash dir $topdir/.Trash/$uid */ globaldir = g_build_filename (topdir, ".Trash", NULL); if (g_lstat (globaldir, &global_stat) == 0 && S_ISDIR (global_stat.st_mode) && (global_stat.st_mode & S_ISVTX) != 0) { trashdir = g_build_filename (globaldir, uid_str, NULL); if (g_lstat (trashdir, &trash_stat) == 0) { if (!S_ISDIR (trash_stat.st_mode) || trash_stat.st_uid != uid) { /* Not a directory or not owned by user, ignore */ g_free (trashdir); trashdir = NULL; } } else if (g_mkdir (trashdir, 0700) == -1) { g_free (trashdir); trashdir = NULL; } } g_free (globaldir); if (trashdir == NULL) { gboolean tried_create; /* No global trash dir, or it failed the tests, fall back to $topdir/.Trash-$uid */ dirname = g_strdup_printf (".Trash-%s", uid_str); trashdir = g_build_filename (topdir, dirname, NULL); g_free (dirname); tried_create = FALSE; retry: if (g_lstat (trashdir, &trash_stat) == 0) { if (!S_ISDIR (trash_stat.st_mode) || trash_stat.st_uid != uid) { /* Remove the failed directory */ if (tried_create) g_remove (trashdir); /* Not a directory or not owned by user, ignore */ g_free (trashdir); trashdir = NULL; } } else { if (!tried_create && g_mkdir (trashdir, 0700) != -1) { /* Ensure that the created dir has the right uid etc. This might fail on e.g. a FAT dir */ tried_create = TRUE; goto retry; } else { g_free (trashdir); trashdir = NULL; } } } if (trashdir == NULL) { g_free (topdir); g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, _("Unable to find or create trash directory")); return FALSE; } } /* Trashdir points to the trash dir with the "info" and "files" subdirectories */ infodir = g_build_filename (trashdir, "info", NULL); filesdir = g_build_filename (trashdir, "files", NULL); g_free (trashdir); /* Make sure we have the subdirectories */ if ((g_mkdir (infodir, 0700) == -1 && errno != EEXIST) || (g_mkdir (filesdir, 0700) == -1 && errno != EEXIST)) { g_free (topdir); g_free (infodir); g_free (filesdir); g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, _("Unable to find or create trash directory")); return FALSE; } basename = g_path_get_basename (local->filename); i = 1; trashname = NULL; infofile = NULL; do { g_free (trashname); g_free (infofile); trashname = get_unique_filename (basename, i++); infoname = g_strconcat (trashname, ".trashinfo", NULL); infofile = g_build_filename (infodir, infoname, NULL); g_free (infoname); fd = open (infofile, O_CREAT | O_EXCL, 0666); } while (fd == -1 && errno == EEXIST); g_free (basename); g_free (infodir); if (fd == -1) { int errsv = errno; g_free (filesdir); g_free (topdir); g_free (trashname); g_free (infofile); g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv), _("Unable to create trashing info file: %s"), g_strerror (errsv)); return FALSE; } close (fd); /* TODO: Maybe we should verify that you can delete the file from the trash before moving it? OTOH, that is hard, as it needs a recursive scan */ trashfile = g_build_filename (filesdir, trashname, NULL); g_free (filesdir); if (g_rename (local->filename, trashfile) == -1) { int errsv = errno; g_free (topdir); g_free (trashname); g_free (infofile); g_free (trashfile); if (errsv == EXDEV) /* The trash dir was actually on another fs anyway!? This can happen when the same device is mounted multiple times, or with bind mounts of the same fs. */ g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, _("Unable to trash file: %s"), g_strerror (errsv)); else g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv), _("Unable to trash file: %s"), g_strerror (errsv)); return FALSE; } vfs = g_vfs_get_default (); class = G_VFS_GET_CLASS (vfs); if (class->local_file_moved) class->local_file_moved (vfs, local->filename, trashfile); g_free (trashfile); /* TODO: Do we need to update mtime/atime here after the move? */ /* Use absolute names for homedir */ if (is_homedir_trash) original_name = g_strdup (local->filename); else original_name = try_make_relative (local->filename, topdir); original_name_escaped = escape_trash_name (original_name); g_free (original_name); g_free (topdir); { time_t t; struct tm now; t = time (NULL); localtime_r (&t, &now); delete_time[0] = 0; strftime(delete_time, sizeof (delete_time), "%Y-%m-%dT%H:%M:%S", &now); } data = g_strdup_printf ("[Trash Info]/nPath=%s/nDeletionDate=%s/n", original_name_escaped, delete_time); g_file_set_contents (infofile, data, -1, NULL); g_free (infofile); g_free (data); g_free (original_name_escaped); g_free (trashname); return TRUE; } 

 

可以用c编码，也可以用python编码，其实前面提到的trash工具，就是用python编写的。