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Linux

Linux, whose full name is GNU/Linux, is a set of Unix-like operating system that is free to use and spread freely. It is a multi-user, multi-task, multi-thread and multi-CPU operating system based on POSIX and Unix. With the development of the Internet, Linux has received support from software enthusiasts, organizations and companies all over the world. In addition to maintaining a strong momentum of development in servers, it has made great progress in personal computers and embedded systems. Users can not only intuitively obtain the implementation mechanism of the operating system, but also modify and improve Linux according to their own needs to maximize meet the needs of users.

What is the ACL permission list? Why use ACL lists?

Traditional permissions have only three identities (owner,group,other) with three kinds of permissions (rdhow.x), and there is no way to simply set the permission requirements for a certain user or a certain group. at this time, we need to use ACL (file access control list, Acess Control List) mechanism.

Note: as a result, ACL has been added to almost all common Linux file system mount parameters (ext2/ext3/ext4/xfs, etc.) by default, but rhtl6.0 and previous versions do not support acl by default.

View permission list set permission list getfaclsetfacl-m set permissions-x delete specified user-b close list function

When deleting using the setfacl-x command, the list function cannot be turned off, only the set users and permissions can be deleted.

Mask threshold in facl

The mask threshold is the maximum valid permission that a specified user can obtain.

* * using chmod to reduce file permissions after setting the facl list is likely to damage mask

Mask setting: setfacl-m m: permission value TAG

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You can only change the user permissions in the current interface. When you create a new file, you do not have the permissions previously set.

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Facl's default permission * * defalut permission feature is only set for directories, only for new files or directories in the directory, but not for the directory itself, and does not take effect for the original files in the directory. Defalut permission setting method set-m DVR u: specify user: specify permission directory

Only for directories, only for new files or directories in the directory, no effect for the directory itself, no effect for the existing files in the directory |

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