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Special Command Line Characters

Commands entered at the IDL prompt are usually interpreted as IDL statements to be executed. Other interpretations include executive commands that control execution and compilation of programs, shell commands, and so on. Input to the IDL prompt is interpreted according to the first character of the line, as shown in the following table.


Note
The information in this section applies equally to IDL used in command-line mode or via the IDL Development Environment.

Table 2-4: Interpretation of the First Character in an IDL Command 

Table 2-4: Interpretation of the First Character in an IDL Command 
First Character
Action
.
Executive command. See About Executive Commands for details.
?
Help inquiry.
$
Send an operating system commands to a subprocess.
Note - SPAWN procedure is a more flexible alternative. It need not be used interactively and the standard output of the command can be saved in an IDL string array. See SPAWN for details.
@
Batch file initiation.
or key
Recall / edit previous commands.
Ctrl+D
In UNIX command-line mode, exits IDL, closes all files, and returns to operating system.
Ctrl+Z
In UNIX command-line mode, suspends IDL.
All others
IDL statement.

About Executive Commands

IDL executive commands compile programs, continue stopped programs, and start previously compiled programs. All of these commands begin with a period and must be entered in response to the IDL prompt. Commands can be entered in either uppercase or lowercase and can be abbreviated. Under UNIX, filenames are case sensitive; under Microsoft Windows, filenames can be specified in any case. See Executive Commands for a descriptions of the available executive commands.


Note
Comments (prefaced by the semicolon character in IDL code) are not allowed within executive commands.

Executive commands are used to create $MAIN$ programs. See Creating $MAIN$ Programs for details.

Special Command Line Key Combination

When working at the command line, key combinations can be used to quickly edit a command. The line-editing abilities and the keys that activate them differ somewhat between the different operating systems. To access the history of commands entered at the command line, see Recalling Commands.


Note
The behavior can also differ within the same operating system, between the Command prompt for IDL and the Command line on the IDLDE.

The table below lists the edit functions and the corresponding keys.

Table 2-5: Command Recall and Line Editing Keys 

Table 2-5: Command Recall and Line Editing Keys 
Function
UNIX
Windows
Move cursor to start of line
Ctrl+A or Home
Home
Move cursor to end of line
Ctrl+E or End
End
Move cursor left one character
Left arrow
Left arrow
Move cursor right one character
Right arrow
Right arrow
Move cursor left one word
Ctrl+B,
(R13 on Sun Keyboard)
Ctrl+left arrow
Move cursor right one word
Ctrl+F,
(R15 on Sun Keyboard)
Ctrl+right arrow
Delete from current to start of line
Ctrl+U
 
Delete from current to end of line
Ctrl+K
 
Delete entire line
   
Delete current character
Ctrl+X or Ctrl+D
Delete
Delete previous character
Ctrl+H, or Backspace, or Delete
Backspace
Delete previous word
Ctrl+W, or Esc-Delete
 
Generate IDL keyboard
interrupt
Ctrl+C
Ctrl+break
Move back one line in
recall buffer
Ctrl+N, Up arrow
Up arrow
Move forward one line in
recall buffer
Down arrow
Down arrow
Redraw current line
Ctrl+R
 
Overstrike/Insert
Esc-I
 
EOF if current line is
empty, else EOL
Ctrl+D
 
Search recall buffer for text
Available only in command-line mode. Enter ^ , then input search string at prompt.
 
Insert the character at the current
Executive Commands position
any character
any character

  IDL Online Help (June 16, 2005)