Interrupting or Aborting Execution

To manually stop programs that are running, issue a keyboard interrupt by typing Ctrl+C (UNIX) or Ctrl+Break (Windows). A message indicating the statement number and program unit being executed is issued on the terminal or IDL Command Log acknowledging the interrupt. The values of variables can be examined, statements can be entered from the keyboard, and variables can be changed. The program can be resumed by issuing the .CONTINUE executive command to resume or the .STEP executive command to execute the next statement and stop.

Variable Context After Interruption

The variable context after a keyboard interrupt is that of the program unit in which the interrupt occurred. By typing the statement RETURN, the program context will revert to the next higher calling level. The RETALL command returns control to the main program level. If any doubt arises as to which program unit in which the interrupt occurred, the HELP procedure can be used to determine the program context. IDL checks after each statement to see if an interrupt has been typed. Execution does not stop until the statement that was active finishes; thus, considerable time can elapse from the time the interrupt is typed to the time the program interrupts.

Aborting IDL

If you find it necessary to abort IDL rather than exiting cleanly using the EXIT command, do one of the following:

UNIX: As with any UNIX process, IDL can be aborted by typing Ctrl+\.This is a very abrupt exit—all variables are lost, and the state of open files will be uncertain. Thus, although it can be used to exit of IDL in an emergency, its use should be avoided.

Note
After aborting IDL by using Ctrl+\ , you may find that your terminal is left in the wrong state. You can restore your terminal to the correct state by issuing one of the following UNIX commands:

% reset or % stty echo -cbreak

Windows: There is no abort character for IDL for Windows.