Special permissions

The permissions or mode of a file you we will be familiar with is Read, Write, and eXecute (RWX). These permissions can be set to the three objects:

  • User
  • Group
  • Others

The standard permissions are shown with their octal notation, should you want a quick revision exercise, as follows:

Special permissions

There is a fourth block of permissions that precedes user, group, and others. This block is for the special permissions; however, rather than representing RWX, the permissions comprise of:

  • The set user ID (SUID) bit
  • The set group ID (SGID) bit
  • The sticky bit

Using symbolic notations, these permissions can be added to file1, which acts as our axiom for the ...

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