Local and Global Shell variable (export command)

• Normally all our variables are local.
• Local variable can be used in same shell, if you load another copy of shell (by typing the /bin/bash at the $ prompt) then new shell ignored all old shell's variable.
• Global shell defined as: "You can copy old shell's variable to new shell (i.e. first shells variable to seconds shell), such variable is know as Global Shell variable."
• To set global varible you have to use export command. Syntax:

  export variable1, variable2,.....variableN
  

  Examples:

  $ vech=Bus
  $ echo $vech
  Bus
  $ export vech
  $ /bin/bash
  $ echo $vech
  Bus
  $ exit
  $ echo $vech
  Bus