chmod command

Definition:

• Change file mode bits, change file permissions of file or directory

Synopsis:

• chmod [OPTION]... MODE[,MODE]... FILE...
  • symbolic mode
  • The format of a symbolic mode is [ugoa...][[-+=][perms...]...]
    • where perms is either zero or more letters from the set rwxXst, or a single letter from the set ugo.
      • rwx
      • X
      • s: set user (Set User ID Bit) or group ID (Set Group ID Bit) on execution
      • t: Sticky Bit
    • Multiple symbolic modes can be given, separated by commas.
• chmod [OPTION]... OCTAL-MODE FILE...
  • absolute mode
  • The first digit selects the set user ID (Set User ID Bit) (4) and set group ID (2) (Set Group ID Bit) and restricted deletion or sticky (1) attributes (Sticky Bit).
  • The second digit selects permissions for the user who owns the file: read (4), write (2), and execute (1);
  • the third selects permissions for other users in the file’s group, with the same values
  • the fourth for other users not in the file’s group, with the same values.

List of options:\

• -c, --changes
  • like verbose but report only when a change is made
• -f, --silent, --quiet
• -v, --verbose
  • output dianostic for every file
• -R, --recursive