Lesson 1

Date: 5/31/2017
User accounts, files and directories, processes, system commands.
Linux System Administration


File Permissions and Ownerships

  • Permissions
    Octal Binary Permission Meaning
    0 000 none All turned off
    1 001 --x Execute
    2 010 -w- Write
    3 011 -wx Write, execute
    4 100 r-- Read
    5 101 r-x Read, execute
    6 110 rw- Read, write
    7 111 rwx Read, write, execute

  • File Ownerships: USER, GROUP

  • Changing permissions
    Permissions are applied for USER, GROUP and OTHERS (rwx rwx rwx)
    
    chmod 660 testf.txt
    ls -l  testf.txt
    
    -rw-rw----    1 mike   staff          0 Jan 18 10:26 testf.txt
    

  • umask sets default permission for files and directories.
    For example,
    
    umask 022
    
    777 (directory) 666 (file)
    -022 (umask) -022 (umask)
    755 (permission) 644 (permission)



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