Recalling Commands

Application Programming: Creating and Running Programs in IDL

Recalling Commands

By default, IDL saves the last 20 commands entered in a recall buffer. These command lines can be recalled, edited, and re-entered. The up-arrow key ( ) on the keypad recalls the previous command you entered to IDL, moving backward through the command history list. Pressing it again recalls the previous line, and so on. The down-arrow key ( ) on the keypad moves forward through the command history. When a command is recalled, it is displayed at the IDL prompt and can be edited and/or entered.

You can view the contents of the recall buffer in the following ways:

Use the arrow keys to view the entries in the buffer one at a time.

Use the HELP procedure with the RECALL_COMMANDS keyword to display the entire contents of the recall buffer in the IDL Output Log.

Right-click on the Command Line in the IDL Development Environment. The 20 most recent commands in the command recall buffer are displayed, and can be selected and re-executed.

The command recall feature is enabled by setting the IDL_EDIT_INPUT preference to true, which sets the system variable !EDIT_INPUT to a non-zero value (the default is 1). See !EDIT_INPUT for details.

Changing the Number of Lines Saved

You can change the number of command lines saved in the recall buffer by setting the IDL_RBUF_SIZE preference equal to a number other than one (in the IDL Development Environment, you can set this value via the General tab of the IDLDE Preferences dialog as well.) In order for the change to take effect, IDL must be able to process the assignment statement before providing a command prompt. This means that you must put the assignment statement in the IDL startup file. See Startup Files for more information on startup files.

For example, placing the line

!EDIT_INPUT = 50

in your IDL startup file changes the number of lines saved in the command recall buffer to 50.

See !EDIT_INPUT and General Preferences for additional details.

IDL Online Help (March 06, 2007)