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
This article is from the blog "Write to Yourself", so be sure to keep this source http://zhaodongwei.blog.51cto.com/4233742/1769604
Linux umask Default Rights Assignment command