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<>1. 用户概念
<>将用户加入白名单
<>2. 权限的定义
<>3. 文件权限
角色和文件属性是一一对应的关系:
拥有者-所属组-其他人
rwx - rwx - rwx
<>4. 文件类型
<>5. chmod 修改文件属性
<>6. chown/chgrp 修改文件所属角色
<>7. umask
<>8. file指令
<>9. 目录的权限
<>10. 粘滞位
首先要明确一点:粘滞键是用于公共目录下的,也就是777(原因:other用户可以删除拥有者的文件,需要写入权限)
<>11. 关于权限的总结
1.目录的可执行权限是表示你可否在目录下执行命令。
2.如果目录没有-x权限,则无法对目录执行任何命令,甚至无法cd 进入目, 即使目录仍然有-r 读权限
(这个地方很容易犯错,认为有读权限就可以进入目录读取目录下的文件)
3.而如果目录具有-x权限,但没有-r权限,则用户可以执行命令,可以cd进入目录。
但由于没有目录的读权限,所以在目录下,即使可以执行ls命令,但仍然没有权限读出目录下的文档