Linux umask Default Rights Assignment command

Command for default permission assignment umask

[Email protected] test]# mkdir newdir

[email protected] test]# Touch NewFile

[Email protected] test]# LS-LRT

Total 4

Drwxr-xr-x. 2 root root 4096 Apr 17:07 newdir

-rw-r--r--. 1 root root 0 Apr 17:08 newfile

Create a directory with default permissions of 755

Create file, default permission is 644

Why is the default permission 755,644 instead of the other value?

Site Directory security permissions: Directory 755, File 644 is a relatively secure permission (user root and user group root)

Linux system default Permissions policy: Allow browsing, viewing, but prohibit creation and modification, add files and content.

Common users create files and directories

Table of Contents 775, File 664

[email protected] ~]$ Touch NewFile

[Email protected] ~]$ mkdir newdir

[Email protected] ~]$ LS-LRT

Total 8

-rw-r--r--. 1 ZJJ zjj 6 APR 11:22 hi.txt

-rw-rw-r--. 1 zjj zjj 0 Apr 17:23 newfile

Drwxrwxr-x. 2 zjj zjj 4096 APR 17:23 newdir

[Email protected] ~]$ umask

0002

Control the Umask place in/etc/profile

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Such as:

[[email protected] ~]$ id-gnzdw[[email protected] ~]$ id-unzdw[[email protected] ~]$ umask0002

Note: The average user's umask may not be 002

FILE-only general calculation method:

Default file permissions calculation method under root

1. Assume that the Umask value is: 022 (all bits are even)

666 the start permission value of the ==> file

022-Value of ==>umask

------

644

2. Assume that the Umask value is: 045 (other user group bits are odd)

666 the start permission value of the ==> file

045-Value of ==>umask

------

621 ==> the computed permissions. Since the last digit of umask is 5, in the user group the odd digit plus 1

001+

------

622 ==> Real files are limited to

command example:

1.umask default 022 when creating directories and files

[[email protected] ~]# umask                                           #默认为0220022 [roo[email protected] ~ ]# cd /home/zdw/[[email protected] zdw]# mkdir 022dir                                  #创建文件夹 [[email protected] zdw]# ls - ld 022dir/                               #777-022 permission is 755drwxr-xr-x.  2 root root 4096 may  3 10:25 022dir/[[email protected]  zdw]# touch 022file                                #创建文件 [[email protected]  zdw]# ls -l 022file                                 #666-022 permissions for 644-rw-r--r--.  1 root root 0 May  3 10:26  022file

Note: The permissions of the folder maximum is 777, with 777-022, the permissions of the folder, the maximum file permissions of 666, with 666-022, the permissions of the file

2.umask set to 333

[[email protected] zdw]# umask 333                                     #更改umask为333 [[Email protected] zdw]# umask0333[[email  protected] zdw]# mkdir 333dir                                  #创建文件夹 [[email protected] zdw]# ls -ld 333dir/                                #777-333 permissions for 444dr--r--r--.  2 root root 4096  May  3 10:31 333dir/        [[email  Protected] zdw]# touch 333file                                #创建文件 [[email  protected] zdw]# ls -l 333file                                 #666-333 in odd digits plus 1 permissions for 444-r--r--r--.  1 root root 0 may  3 10:32  333file

Note: The odd permission bit does not affect the directory, the file bit is odd, plus 1 can

Learn from: Old boy

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Linux umask Default Rights Assignment command