Shell Variables   «Prev 

Using Variable Substitution

Basic substitution returns the value of the variable enclosed in braces.
Variable Substitution returns the value of the variable enclosed in braces

  1. $ {FLIGHT}: Basic substitution returns the value of the variable enclosed in braces.
  2. $ {PHONE:-1-800-555-1212}: Returns the value of 1-800-555-1212 if the variable PHONE has no value (is not set).
  3. $ {PHONE:-1-800-555-1212}: If the variable PHONE has no value (is not set), this statement returns the value of 1-800-555-1212 and sets the value of PHONE to 1-800-555-1212.
  4. $ {CREDIT_OK:+Approved}: Returns the string “Approved” if the variable CREDIT_OK is set; otherwise a blank string is returned.
  5. $ {#NAME}: Returns the length of the string contained in the variable NAME.
  6. $ {#NAME:?A name is not assigned}: Returns the error message text “A name is not assigned” if the variable NAME has no value (compare to using the :- notation).