chmod command for linux tutorial and Examples

chmod sections description :

• Options :the following table describe the option list

  Option	Description
  -f, –silent, –quiet	suppress most error messages
  -v, –verbose	output a diagnostic for every file processed
  -c, –changes	like verbose but report only when a change is made
  -c, –reference=RFile	use RFile’s mode instead of MODE values
  -R, –recursive	change files and directories recursively
  –help	display help and exit
  –version	output version information and exit

• Permissions Using Numeric mode :The format of a numeric mode is ‘augo‘ ,A numeric mode is from one to four octal digits (0-7),to set permission you pass the numbers permission to owner group everyone for example chmod nnn is setting permission n to owner and the second n to group and third n to everyone (n is the numeric mode that we will describe bellow) :
  
  • 4 maps for “read“
  • 2 maps for “write“
  • 1 maps for “execute“
  • 0 maps for “no permission.”
  • 7 is combination of permissions 4+2+1 (read, write, and execute)
  • 6 is combination of permissions 4+2+0 (read, write, and Not execute)
  • 5 is 4+0+1 (read, no write, and execute).
• Permissions Using symbolic Permissions Notation :The letters u, g, and o mapping to “user“, “group“, and “other” in order. and the letters “r“, “w“, and “x” stand for “read“, “write“, and “execute“, respectively.and you will need to use The equals sign (=) between the u,g,o and rwx as example:
  chmod u=rwx,g=rx,o=w example.txt
  This is means apply read write and execute permissions to owner, and assign read and execute to group , and assign write permission to other.