Chmod

permissions11

A chmod is used to change permission of files and directories.

  • form:     chmod  [options]  permissions  filename

permissions

can be represented in two ways.

  • Alphabetic combination
  • Numeric combination

 

Alphabetic combination

  • User
    • a: All people
    • u: owner
    • g: group
    • o: others
  • Permission
    • r: read
    • w: write
    • x: execute
  • Example:
    • chmod u=rwx practice.txt : Owner gets all permissions on practice.txt.
    • chmod g-w practice.txt : Group’s write permission on practice.txt is removed.
    • chmod o+rx practice.txt : Others get additional read and execute permissions.
    • chmod a=rwx practice.txt : All people get all permissions.

 

Numeric Combination

chmod-775

  • Permission
    • 4: read
    • 2: write
    • 1: execute
  • Example:
    • chmod 755 practice.txt : owner gets all permission. Group and others get read and execute permission.
    • chmod 777 practice.txt : All people get all the permissions.

 

options

Screen Shot 2016-08-22 at 2.12.06 PM

 

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