The XC editor on UNIX: Part 4.2

Editing an Existing File

1. Restart the XC editor by typing

             xc census.data

   and pressing the ENTER or RETURN key. The screen will be filled with the text you previously typed. It will display only the first 17 lines of the file.

2. Add lines to your file. On the command line, type

             bottom

   and press the ENTER or RETURN key to move to the last line of the file. Then type

             input

   and press the ENTER or RETURN key.

   Type the following lines as you did in the previous section.

             MA<TAB>NE<TAB><TAB>6016          
             RI<TAB>NE<TAB><TAB>1003          
             CT<TAB>NE<TAB><TAB>3287          
             NY<TAB>MA<TAB><TAB>17990          
             NJ<TAB>MA<TAB><TAB>7730          
             PA<TAB>MA<TAB><TAB>11882

   When you are finished, remember to press the ENTER or RETURN key twice to leave insert mode and return to command mode.

   XC uses the "current line" (the line directly above the scale) as its reference point. The current line is marked by ")))))". The "input" command tells XC to insert the lines you type after the current line. When you first start XC, the top of the file is the current line. To change the current line, you can type any of the following commands on the command line

   	bottom		makes the last line of the file the current line
   	top		makes the top of your file the current line
   	down n		moves the current line n lines down (e.g., down 20)
   	up n		moves the current line n lines up (e.g., up 8)
   	:n		moves the current line to line n (e.g., :7)

3. Make changes to your file. There are three ways to move around in your file and make changes to it:
   • Use arrow keys to move the cursor to the position on the screen where a change is needed in the text, and then type over, delete, or insert characters.

   • Use "prefix area" commands to add, delete, copy, move lines, and duplicate blocks of lines. The first five columns on the left side of the display make up the prefix area. The line numbers are displayed there.

   • Type XC commands on the command line near the bottom of the screen. You can move the cursor quickly from the input area to the command line by pressing the ENTER or RETURN key.

   In the next few steps, you can try all three methods.

4. Practice moving around and making changes to your file using the arrow keys.
   • Position the cursor on the "1" in the number "12938" on the ninth line of the file. (If this line isn't visible, type "top" on the XC command line and press the ENTER or RETURN key.) Type

               975

     Notice that the characters "975" overwrite the first three characters in "12938". With the cursor still positioned on the "3" that is left from "12938", press the character-delete key twice to remove the extra characters "38".

     Note: If you are using telnet, HyperTerminal or Kermit on a microcomputer with an Ethernet card, see the discussion in Part 4.1 about which key acts as a character-delete key.

   • Move the cursor to the "E" in "DE" on line 1 and press the insert key (see Part 4.1). Notice that on the first line of the display, "CMR" changes to "INSERT CMR" to indicate that you are in "character insert mode" rather than "overwrite mode." Then type

               elaware

     and press the insert key again to end the insertion. Notice that the "INSERT CMR" status message changes back to "CMR." Finally, remove the trailing "E" by pressing the character-delete key. The net effect is to change "DE" to "Delaware".

5. Try some of the prefix area commands. Move the cursor to any position in the five-column prefix area of the line

             GA  South     6478

   (Hint: Press CTRL-A to move quickly to the next line's prefix area.)
   • To add a new line below this line, type "a" over any of the blanks or the line number itself. It will look something like "a 8" or " a 8" or " a". Press the ENTER or RETURN key. An empty line will open up. On this new line, type the line

               ID<TAB>MT<TAB><TAB>296

   • To delete a particular line, move the cursor to the prefix area of that line, and type "d" anywhere in the five-space area. The next time you press the ENTER or RETURN key, the line will be deleted. Try this on the line

               DC  South     607

     If the line you are looking for is not on the screen, you can view the page before (or after) by:
     • typing "backward" (or "forward") at the command line and pressing the ENTER or RETURN key;

     • typing "up 18" (or "down 18") at the command line and pressing the ENTER or RETURN key (use 25 rather than 18 for an X terminal);

     • pressing the ESC key, then 7 (or ESC then 8) as noted on the menu at the bottom of the screen;

     • pressing F7 (or F8) if you are not using telnet, HyperTerminal or Kermit on a microcomputer with an Ethernet card.

   • To move a line to a new location in the file, place the cursor in that line's prefix area and type "m". For example, do this for the line

               KY  South     3685

     Then move the cursor to the prefix area of the line

               MS  South     2573

     and type "f" (for "following") anywhere in the prefix area. Press the ENTER or RETURN key to move the first line you marked to a line following the second line. If you had typed "p" rather than "f", the first line would have "preceded" rather than "followed" the second line.

   • To copy a line to a new location in the file, place the cursor in the prefix area and type "c". For example, do this for the line

               KY  South     3685

     Then move the cursor to the prefix area of the line

               TN   South   4877

     and type "f" (for "following") anywhere in the prefix area. Press the ENTER or RETURN key to copy the first line you marked to a line just after the second line.

   • You can add, delete, move, copy, or replicate more than one line at a time by preceding or following the "a", "d", "m", "c", or "r" commands with the number of lines you want to affect. For example, if you type "5d" or "d5" in the prefix area of line 11, and press the ENTER or RETURN key, you will delete lines 11 to 15. Or, if you type "3r" in the prefix area of line 5, three replicates (copies) of line 5 will be inserted immediately after line 5.

     You also can mark the first and last line of the group of lines you want to affect by typing two of the appropriate prefix codes. For example, to delete lines 11 to 15, type "dd" in the prefix areas of lines 11 and 15. The prefix (and text) areas will look like this:

               dd 11 <text of line 11>
                  12 <text of line 12>
                  13 <text of line 13>
                  14 <text of line 14>
               dd 15 <text of line 15>

     The lines will be deleted when you press the ENTER or RETURN key.

6. Use some XC commands from the command lines at the bottom of the screen. Note that you must leave at least one blank after the command line's arrow (====>). If you don't, XC will make the terminal beep.
   • Remember that XC uses the current line (the line above the scale) as its reference point and works downward through the file. The following commands allow you to search through the file for a particular number, word, or string of characters, and make several changes at once.

     	locate /thing/		moves the current line down to the next line containing "thing". The word "locate" is optional.
     	locate -/thing/		moves the current line up to the previous line containing "thing". The word "locate" is optional.
     	change /old/new/		changes the first occurrence of the word "old" to the word "new" on the current line. The command "change" may be abbreviated as "ch".
     	change /old/new/ 1 *		changes all occurrences (*) of the word "old" to the word "new" on the current line (1).
     	change /old/new/ * *		changes all occurrences (*) of the word "old" to the word "new" from the current line to the end of the file (*).

   • You can have XC ignore the case (uppercase and lowercase) of the search target by first typing the XC command

               case mixed ignore

   • Move the cursor to the command line by typing

               top

     and pressing the ENTER or RETURN key. Scanning from the current line, find the first line in the file with the characters "NE" by typing

               locate /NE/

     and pressing the ENTER or RETURN key. Then move the current line down 2 lines by typing

               down 2

     and pressing the ENTER or RETURN key.

     Change all occurrences of "NE" to Northeast" from that point on by typing

               change /NE/Northeast/ * *

     and pressing the ENTER or RETURN key. Notice the message line at the top of the screen.

   • Use ESC 7 (PF7) and ESC 8 (PF8) to browse the contents of the changed file.

7. Quit the XC editor. To save the changes, type

             file

   on the command line and press the ENTER or RETURN key. Remember, to quit without saving the changes, type

             qquit

   instead and press the ENTER or RETURN key.