Permission management commands for common Linux Commands

Linux common command-permission management command chmodu/g/o +/-/r/w/x change permission user/user group/other user increase/decrease/Grant read/write/execute r4w2x1rwxr-xr -- 754752: rwxr-x-w-question: if other users have 7 permissions on the file... permission management commands for common Linux Commands


Chmod u/g/o +/-/= r/w/x change permission user/user group/other user increase/decrease/Grant read/write/execute
R = 4 w = 2 x = 1 rwxr-xr -- 754 752: rwxr-x-w-

Question: if other users have 7 permissions on the file, ask whether the file can be deleted.
Answer: No, unless other users have 2 permissions on the folder where the file is located.

File rwx: r indicates that cat, more, head, and tail operations can be performed on the file, and w indicates that the file can be operated by echo and vi, r indicates that commands and scripts can be run on it.
Directory rwx: r-ls w-touch, mkdir, rm x-cd
Add useradd helen passwd helen



After a file is created, the system grants it the corresponding permissions by default. you can view the permissions by using umask.

0022
0-special permission bit
022-user permission bit, permission mask value.
777-022 = 755 is the correct permission
Note that it is uppercase-S.

Linux permission rules: the file created by default cannot be granted the executable x permission.
Change permission: umask + mask value