There is several ways to recall or change a previously typed command in IRAF. The "eparam" and "ehistory" commands have two such modes; an immediate execution and editing. A summary of these shortcuts and their function follows. The "^" is for immediate execution and the "ehistory" command which edits the command line recalled.

      cl> ^			Rerun the previous command

      cl> ^nite1^nite2^		Rerun the previous command but
				substituting 'nite2' for the first
				appearance of 'nite1' 

      cl> ^nite1^nite2^g	Same as above but subttituting
				all occurances of 'nite1' with
				'nite2'

      cl> ^rfits		Rerun the last 'rfits' command

      cl> ^?FLAT		Rerun the last command containing
				'FLAT' anywhere

      cl> history		List the last few commands in the
				history buffer

      cl> history 50		List the last 50 commands in the
				history buffer

      cl> ^37			Rerun command number 37 from the
				history list

      cl> ^-2			Rerun the command before the
				previous one

      cl> task ^2 ^1		Run the 'task' with the first
				and second arguments of the
				previous command reversed

      cl> task ^$		Run 'task' with the last argument
				of the previous command

      cl> task ^*		Run 'task' with all the arguments
				of the previous command

Now the "^" command may behave like the editing command if the cl parameter "ehinit" is set to "verify". If you wish to change this, edit the parameters of "cl". The UNIX "ehistory" is much like the command recall in VMS. Typing an e will present the last command in the history list. To scroll up through this list just type the up arrow. Now to change something on the line, move the cursor using the left arrow, delete and type in the change (this deletes and adds to the left). If a task name is specified after the "ehistory" command it recalls the last command using that task. For example, typing e display will recall the last display command used with its previous parameters. You may now edit this command. Typing return, (no matter where the cursor is) will run the task.