1.The most privileged user superuser or root, has a user ID of 0.The root user is usually the system administrator.2.The process uses the effective IDs for determining access permission for files.

.gitignore 文件的习惯，以免将来误提交这类无用的文件。文件 .gitignore 的格式规范如下：• 所有空行或者以注释符号 ＃ 开头的行都会被 Git 忽略。• 可以使用标准的 glob 模式匹配。• 匹配模式最后跟反斜杠（/）说明要忽略的是目录。• 要忽略指定模式以外的文件或目录，可以在模式前加上惊叹号（! ）取

Git - how to revert uncommitted changes including files and folders?You can run these two commands:# Revert changes to modified files.git reset --hard# Remove all untracked files and

误删/tmp目录导致ubuntu程序各种崩溃解决方案：关闭对话框，正常打开系统和命令窗口，修改/tmp的权限chmod 1777 /tmp----------------------------------------------------------------------------------------------------------------