getopts command

• This command is used to check valid command line argument are passed to script. Usually used in while loop. Syntax:

  getopts {optstring} {variable1}
  

  getopts is used by shell to parse command line argument.
• Each time it is invoked,getopts places the next option in the shell variable variable1,
• When an option requires an argument, getopts places that argument into the variable OPTARG.
• Example; We have script called http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/aniani. which has syntax as

  ani -n -a -s -w -d
  Options: These are optional argument
  -n name of animal
  -a age of animal
  -s sex of animal
  -w weight of animal
  -d demo values (if any of the above options are used their values 
  are not taken)
  

  For executing;

  $ ani -n Lassie -a 4 -s Female -w 20Kg
  $ ani -a 4 -s Female -n Lassie -w 20Kg
  $ ani -n Lassie -s Female -w 20Kg -a 4
  $ ani -w 20Kg -s Female -n Lassie -a 4
  $ ani -w 20Kg -s Female
  $ ani -n Lassie -a 4
  $ ani -n Lassie
  $ ani -a 2
  

• See because of getopts, we can pass command line argument in different style