Command note chmod, umask

Changing access rights chmod

Format: chmod [Who][+1-1=][mode] FileName

Parameters: Who=u, g O, a

Mode: +-=

Rights alphanumeric combination: R-4 w-2 x-1 r-x-5 r---4--x-1

#chmod u=rwx,g=r--, o=r--123.txt

#chmod 744 123.txt

#ls-L 123.txt

-rwxr--r--1 root root 12777 December 4 20:31 123.txt

Adding or deleting a file to a permission

# chmod u-x,g+w,o--123.txt

# ls-l 123.txt

-rw-rw-r--1 root root 12777 December 4 20:31 123.txt

Chmod-r XYZ Filname

-R indicates cascading changes

Root User directory permissions default 755, file default permissions 644

UMASK Specifies the default file or directory permissions

View Umask Value input Umask Enter, default is 0022, directory permission is 755, file permission is 644

All directories under Linux must have X permissions

0022 usually only after three bits 022=----w-w-

Note: The user establishes the ordinary file does not have the X permission namely 666, the directory permission all is open namely 777

755 rwx rwx rwx-----w-w-= rwx r-x r-x

644 rw-rw-rw------w-w-= rw-r--r--

Command note chmod, umask