HP 3000 Manuals HP 3000 Manuals
Lesson 4 Mistakes and Corrections
Lesson 4 presents error messages and correcting command errors.
* mistakes and error messages
* correcting errors
* reenter the command
* use backspace [[backspace]] to edit the command
* use the REDO command to edit the command
Mistakes
Are you still logged on? If you are not, log on again (HELLO your logon
identity Return).
What if you make a mistake while entering a command?
Make a mistake. Enter:
SHOWHOBReturn
Your screen looks like this:
________________________________________________________________________
| |
| |
| :SHOWHOB |
| UNKNOWN COMMAND NAME. (CIERR 975) |
| :_ |
| |
________________________________________________________________________
Error messages
This mistake is just a typing error. The computer does not recognize the
command, so it displays an error message that shows the following:
* a brief explanation of the problem (UNKNOWN COMMAND NAME)
* a code that identifies the error message (command interpreter
error 975)
Correcting an error
There are various ways of correcting errors. Choose the method that is
most convenient.
Reenter the command.
You may choose to reenter the command correctly.
Enter:
SHOWJOBReturn
to send the correct command to the computer. If you enter the command
correctly, it executes, and you see the results.
Backspace over the error.
Another way to correct an error is to use the backspace key [[backspace]]
to go back to the character where you made the first mistake and reenter
the remainder of the command.
NOTE This method only works if you have not yet pressed the Return key.
Type SHOWHOB again. DO NOT PRESS RETURN YET.
* Press the backspace key three times
[[backspace]][[backspace]][[backspace]] (or as many times as it
takes to place the cursor directly on the second letter "H.")
HOB may still appear on the screen, but it has been erased from
your terminal's memory. The letters "H," "O," and "B" would not
be sent to the computer if you were to press Return. In effect,
you have reduced the entry to SHOW.
* When the cursor is on H, type JOB.
* Press Return.
These two methods are best used for short commands. Notice that you have
to reenter the command from the first mistake all the way to the end. As
you become a more experienced MPE/iX user, reentering lengthy commands
using these methods could become tedious.
The REDO command.
The REDO command allows you to edit commands and then reexecute them.
When the command line becomes long and complex--and some do--REDO is the
easier solution.
Enter:
COWEMReturn
You should see this on the screen:
________________________________________________________________________
| |
| |
| :COWEM |
| UNKNOWN COMMAND NAME. (CIERR 975) |
| :_ |
| |
________________________________________________________________________
Now enter:
REDOReturn
You should see this on the screen:
________________________________________________________________________
| |
| |
| :REDO |
| COWEM |
| _ |
| |
________________________________________________________________________
Read ahead before doing anything more at your terminal.
REDO subcommands.
REDOReturn retrieves the most recent command entered on the computer and
gives it back to you for editing. The REDO command allows you to make
the editing changes on the line below the retrieved command. Notice that
there is no system prompt (:), just the cursor.
Four simple and useful subcommands of REDO are DELETE, INSERT, REPLACE,
and UNDO:
D Deletes the character above it.
I Inserts character(s), starting at the character
above it.
R Replaces character(s), starting at the character
above it.
U Cancels the effect of the previous D, I, or R
subcommand.
These subcommands can be entered in uppercase or lowercase letters.
Use the spacebar and backspace ([[backspace]]) to place the cursor
exactly under the place where you want to start your corrections.
Correcting commands with REDO.
Correcting with REDO follows a pattern of steps:
STEP 1. Make one correction on the line.
STEP 2. Press Return.
Pressing Return once displays the line again for another
correction.
STEP 3. If the line is now correct, press Return again.
Pressing Return twice in a row signals the end of your
corrections and sends the command line to the computer for
execution.
If the line is still not correct, go to STEP 4.
If you wish to cancel your previous correction(s), go to STEP 5.
STEP 4. Make another correction on the line. Go to STEP 3.
STEP 5. Type U and press Return. This cancels the effect of the
previous D, I, or R subcommand.
Entering a UReturn, then another UReturn cancels all previous
REDO subcommands and restores the command being corrected to it
original form.
Now correct your last command entered, COWEM
First, use the subcommand R to replace the C with an S.
You must place the subcommand letter R directly under the letter to be
changed. For this first correction, be sure that the cursor is already
under C.
Enter:
RSReturn
Your screen should look like this:
________________________________________________________________________
| |
| |
| :REDO |
| COWEM |
| RS |
| SOWEM |
| _ |
| |
________________________________________________________________________
Each time you make a correction, the computer shows you the command with
the new edits that you made and waits for more edits.
NOTE The _ mark is used here to represent pressing the spacebar one
time.
Insert H between S and O this way:
_IHReturn
Now your screen should show the following:
________________________________________________________________________
| |
| |
| :REDO |
| |
| COWEM |
| RS |
| SOWEM |
| IH |
| SHOWEM |
| _ |
| |
________________________________________________________________________
Now replace EM with ME this way:
____RMEReturn
At this point your screen should show:
________________________________________________________________________
| |
| |
| :REDO |
| |
| COWEM |
| RS |
| SOWEM |
| IH |
| SHOWEM |
| RME |
| SHOWME |
| _ |
| |
________________________________________________________________________
The word SHOWME should be on the screen, properly spelled.
Now that the command is correct, press the return key again:
Return
This concludes the editing and sends the command to the computer for
execution. You should now see the SHOWME display.
As mentioned earlier, the U subcommand lets you cancel or undo, the
effects of a D, R, or I subcommand.
To see how this works, execute the SHOWTIME command and make the
following corrections using the REDO command.
Replace TIME with JOB this way:
____ddddJOBReturn
Next, replace JOB with ME this way:
____dddiMEReturn
Delete SHOW as follows:
ddddReturn
Now, enter:
UReturn
Notice that the previous edit, deleting SHOW, has been undone and SHOWME
reappears on the screen.
At this point, you have one of three choices:
1. Continue to edit with D, R, or I, or
2. Press Return once to execute the SHOWME, or
3. Press UReturn again.
Perform the third choice now by entering:
UReturn
SHOWTIME returns to the screen canceling all of the previous REDO
subcommands.
Press Return to execute SHOWTIME.
Your screen should show something
like this:
________________________________________________________________________
| |
| |
| :REDO |
| SHOWTIME |
| |
| |
| ddddJOB |
| SHOWJOB |
| dddiME |
| SHOWME |
| dddd |
| ME |
| U |
| SHOWME |
| U |
| SHOWTIME |
| |
| :SHOWTIME |
| FRI, JUN 29, 1990 4:35 PM |
| :_ |
| |
________________________________________________________________________