Calculate file permissions based on the Umask value

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1th Chapteraccording toUmaskvalue, calculating file permissions1.1Numeric Method Calculation1.1.1for Files

use 666 to calculate

if umask any one of the values is an even digit, the direct minus umask value

666-002=664

[Email protected] tmp]$ umask002

[Email protected] tmp]$ touchf002

[Email protected] tmp]$ ls-l f002

-rw-rw-r--1 Xeon Xeon 0 APR 2 13:22 f002

if umask if the value of any bit has an odd number, it is reduced, and any bit odd digit is added 1 that's right.

666-123=543+101=644

[Email protected] tmp]$ umask123

[Email protected] tmp]$touch f123

[email protected] tmp]$ ls-l f123

-rw-r--r--1 root root 0 Apr 6 13:24 f123

1.1.2for Catalogs

in terms of catalogs, it is 777-umask it's over.

777-022=755

[Email protected] tmp]$umask 022

[Email protected] tmp]$ mkdird022

[Email protected] tmp]$ ls-ld d022

Drwxr-xr-x 2 Xeon Xeon 4096 Apr 2 13:43 d022

1.1.3Summary

	Default Maximum Permissions	umask value	User-created permissions
Create a file ( umask all bits are even)	666	002	664
-rw-rw-rw-	--------W	-rw-rw-r--
(default maximum permissions) - ( umask permissions) = (user-created permissions)
Create a file ( umask some or all of the digits are even)	666	123	644
-rw-rw-rw-	---x-w--wx	-rw-r--r--
(default maximum permissions) - ( umask permissions) + ( umask odd number of arbitrary digits plus 1 ) = (user-created permissions)
Create a Directory	777	022	755
Drwxrwxrwx	D----w--w-	Drwxr-xr-x
(maximum default permissions) - ( umask permissions) = (user-created permissions)

1.2umask-scalculation Method1.2.1for Files

( umask value any bit with even)- (umask x on the value of any even digit )= (user-created permissions)

Owner - x , belong to group - x , other users - x

[Email protected] tmp]$ umask002

[Email protected] tmp]$ touchf002

[Email protected] tmp]$ umask-s

U=RWx, G=RWx, o=rx

[Email protected] tmp]$ls-l f002

-RW-rw-R- 1 Xeon Xeon 0 APR 2 13:22 f002

Genus Group - x

[Email protected] tmp]$ umask123

[Email protected] tmp]$ touchf123

[email protected] tmp]$ umask-s

U=rw,g=rx, O=r

[email protected] tmp]$ ls-l f123

-rw-r--r--1 root root 0 Apr 6 : f123

1.2.2for Catalogs

umask-s value is the user-created permission

[Email protected] tmp]$umask 022

[Email protected] tmp]$ mkdird022

[Email protected] tmp]$ umask-s

U=rwx,g=rx,o=rx

[Email protected] tmp]$ ls-ld d022

Drwxr-xr-x 2 Xeon Xeon 4096 Apr 2 13:43 d022

[Email protected] tmp]$ umask033

[Email protected] tmp]$ mkdird033

[Email protected] tmp]$ umask-s

U=rwx,g=r,o=r

[Email protected] tmp]$ ls-ld d033

drwxr--r--2 Xeon Xeon 4096 Apr 2 13:45 d033

1.2.3Summary

	Default Maximum Permissions	umask value	user-created permissions are equal to umask-s	umask value	user-created permissions are equal to umask-s
Create a file ( umask can be odd and even)	666	002	664	123	644
-rw-rw-rw-	--------W	-rw-rw-r--	---x-w--wx	-rw-r--r--
( umask value any bit with even number) - ( umask value on any even digit. x ) = (user-created permissions)
Create a Directory	777	022	755	333	444
Drwxrwxrwx	D----w--w-	Drwxr-xr-x	D-wx-wx-wx	dr--r--r--
umask-s value is the user-created permission

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Calculate file permissions based on the Umask value