The ed Editor
This has always been the aspect of coding that new
creators have most trouble with. It's what discourages most
people from creating lots of stuff, in fact.
With Dead Souls, you can get away with avoiding ed
most of the time, by using the QCS.
But to add special functions to your code, like
magic items, smart NPC's (aka mobs), traps, hidden objects,
etc, you need to edit LPC code.
There is a web-based editing system called
"creweb" that lets you edit mud files from the internet
on your browser. For more info on it: help creweb
But if you can't use creweb, then ed is
the default method for editing files inside the mud.
ed is a simple editing program. It is designed to
work on a line-by-line basis, so it is called a "line editor".
Let's start by looking at, and editing, a small file.
We've coded a sword, and we want to change its description
from "short sword" to "plain sword":
> cd /realms/cratylus/area/weap1) I changed my working directory to my area weapons dir
/realms/cratylus/area/weap:
> ls I listed the contents of that dir:
/realms/cratylus/area/weap/:
1 dagger.c 1 nco_sword.c~ 1 std_sword.c~
1 gsword.c 1 sharpsword.c 1 sword.c
001 gsword.c~ 1 staff.c
1 nco_sword.c 1 std_sword.c
> ed sword.c I ran the ed command on the file sword.c.
/realms/cratylus/area/weap/sword.c, 641 bytes
:n This makes the editor display line numbers next to the lines.
number on, list off
:1z This lists about 20 lines of text
1 /* /domains/Examples/weapon/sword.c
2 * from the Nightmare IV LPC Library
3 * a simple sword example, nothing fancy
4 * created by Descartes of Borg 950402
5 */
6
7 #include <lib.h>
8 #include <damage_types.h>
9 #include <vendor_types.h>
10
11 inherit LIB_ITEM;
12
13 static void create() {
14 item::create();
15 SetKeyName("short sword");
16 SetId( ({ "sword", "short sword" }) );
17 SetAdjectives( ({ "short" }) );
18 SetShort("a short sword");
19 SetLong("A cheap and rather dull short sword.");
20 SetMass(150);
21 SetDollarCost(50);
22 SetVendorType(VT_WEAPON);
:z
22 SetVendorType(VT_WEAPON);
23 SetClass(20);
24 SetDamageType(BLADE);
25 SetWeaponType("blade");
26 }
:15 I displayed line 15
15 SetKeyName("short sword");
:15c I used 'c' to replace line 15
15. * SetKeyName("plain sword"); I entered my replacement text
16. * . I entered a single dot on a blank line
:
16 SetId( ({ "sword", "short sword" }) );
:1z I listed about 20 lines, starting from line 1
1 /* /domains/Examples/weapon/sword.c
2 * from the Nightmare IV LPC Library
3 * a simple sword example, nothing fancy
4 * created by Descartes of Borg 950402
5 */
6
7 #include <lib.h>
8 #include <damage_types.h>
9 #include <vendor_types.h>
10
11 inherit LIB_ITEM;
12
13 static void create() {
14 item::create();
15 SetKeyName("plain sword");
16 SetId( ({ "sword", "short sword" }) );
17 SetAdjectives( ({ "short" }) );
18 SetShort("a short sword");
19 SetLong("A cheap and rather dull short sword.");
20 SetMass(150);
21 SetDollarCost(50);
22 SetVendorType(VT_WEAPON);
:18 I displayed line 18
18 SetShort("a short sword");
:18c I started the replacement of line 18
18. * SetShort("a plain sword"); I entered my replacement text
19. * . I entered a single dot on a blank line
:1z I displayed about 20 lines starting from line 1
1 /* /domains/Examples/weapon/sword.c
2 * from the Nightmare IV LPC Library
3 * a simple sword example, nothing fancy
4 * created by Descartes of Borg 950402
5 */
6
7 #include <lib.h>
8 #include <damage_types.h>
9 #include <vendor_types.h>
10
11 inherit LIB_ITEM;
12
13 static void create() {
14 item::create();
15 SetKeyName("plain sword");
16 SetId( ({ "sword", "short sword" }) );
17 SetAdjectives( ({ "short" }) );
18 SetShort("a plain sword");
19 SetLong("A cheap and rather dull short sword.");
20 SetMass(150);
21 SetDollarCost(50);
22 SetVendorType(VT_WEAPON);
:x I saved and exited
"/realms/cratylus/area/weap/sword.c" 26 lines 633 bytes
Exit from ed.
> update sword I loaded the file into memory
/realms/cratylus/area/weap/sword: Ok
Let's take this step by step:
1) I changed my working directory to my area weapons dir: cd /realms/cratylus/area/weap
2) I listed the contents of that dir: ls
3) I ran the ed command on the file sword.c: ed sword.c
4) Within the editor, I issued the 'n' command. This makes the editor
display line numbers next to the lines.
5) Within the editor, I issued the '1z' command. What 'z' does is display
about 20 lines of the file (the exact number depends on your screen
settings. In my case it's 22). If you happen to be looking at line 1, it
will display lines 1 through to about 20. If you happen to be looking
at line 40, it will display from line 40 to about 60.
If you want to start looking at lines starting at line 15, you
can issue the '15z' command, which basically means "display about 20
lines starting at line 15".
In this case, I wanted to start from the beginning of the file,
so I issued '1z'.
6) '1z' stopped listing the file at line 22, so I entered 'z' again to
list the rest.
7) Since I want to change "short sword" to "plain sword", I examined each
line to find the word "short". I noticed that line 15 has "short" in it,
so to get a look at that line alone, I entered '15'.
8) Now that I'm sure line 15 needs to change, I issue the '15c' command.
'c' indicates that I want to change a line. '15c' means "delete whatever
was in line 15, and replace it with what I am about to type".
9) You can see that my editor prompt changed from ":" to "*". What this
means is that I am now in "input mode". Whatever I type now will be
added to the file. Since my last command in "command mode" was '15c',
I am now replacing that line with what I want the line to contain:
SetKeyName("plain sword");
10) Ok, I replaced the line, but I'm still in input mode. To go back to
command mode, I type a single period and enter, like this:
.
11) I'm back in command mode now. When I list the file contents with
'1z' I can see that line 15 now says what I wanted.
12) Now I see another line that needs changing, so I enter '18' to
get a closer look.
13) Sure enough, 18 needs to change, so I issue '18c'.
14) Like I did for line 15, I enter what the line should be.
15) To return to command mode, I enter a single period on a blank line.
16) I list the file contents, and see that my change was successful.
17) I'm finished making my changes, so I issue the 'x' command. 'x'
means "save the changes I have made, and exit the editor".
18) I am now at my regular command prompt. To load my changes to this
file, I type 'update sword'.
Editor basics, part 2
In the last section you saw what a simple line
replacement looks like in ed. Next we'll talk about some common
ed actions.
ADDING STUFF:
Suppose I want to specify that this sword requires only
one hand to wield it:
> ed sword.c started the editor
/realms/cratylus/area/weap/sword.c, 633 bytes
:n enabled line number printing
number on, list off
:15,22 listed lines 15 to 22
15 SetKeyName("plain sword");
16 SetId( ({ "sword", "short sword" }) );
17 SetAdjectives( ({ "short" }) );
18 SetShort("a plain sword");
19 SetLong("A cheap and rather dull short sword.");
20 SetMass(150);
21 SetDollarCost(50);
22 SetVendorType(VT_WEAPON);
:20a appended to the file after line 20
21. * SetHands(1); entered my added text
22. * . single dot on a blank line to exit input mode
:18,22 displayed line 18 through 22
18 SetShort("a plain sword");
19 SetLong("A cheap and rather dull short sword.");
20 SetMass(150);
21 SetHands(1);
22 SetDollarCost(50);
:x exited editor and saved
"/realms/cratylus/area/weap/sword.c" 27 lines 646 bytes
Exit from ed.
Here you can see that instead of 'c', which replaces, I
used 'a', which adds. I decided my new line would go after line
20, so I issued the command '20a'. Once I was done, I typed
a single dot on a blank line to exit "input mode". You'll notice
I didn't use the 'z' command. Instead, since I knew where my
changes would go, I decided to list lines 18 through 22 with
the command '18,22'. I then issued the 'x' command to save my
changes and exit the editor.
If had I wanted my addition to go in front of line 20,
I could have used the '20i' command.
DELETING LINES
Suppose I'm tired of seeing header lines that no
longer apply to this file. We can delete a single line, or
a range of lines, with the 'd' commmand:
> ed sword.c
/realms/cratylus/area/weap/sword.c, 646 bytes
:n enabled line number printing
number on, list off
:1,10 listed lines 1 to 10
1 /* /domains/Examples/weapon/sword.c
2 * from the Nightmare IV LPC Library
3 * a simple sword example, nothing fancy
4 * created by Descartes of Borg 950402
5 */
6
7 #include <lib.h>
8 #include <damage_types.h>
9 #include <vendor_types.h>
10
:1,5d deleted lines 1 to 5
:1,5 listed (the new) lines 1 to 5
1
2 #include <lib.h>
3 #include <damage_types.h>
4 #include <vendor_types.h>
5
:1d deleted blank line 1
:1z displayed the file starting at line 1
1 #include <lib.h>
2 #include <damage_types.h>
3 #include <vendor_types.h>
4
5 inherit LIB_ITEM;
6
7 static void create() {
8 item::create();
9 SetKeyName("plain sword");
10 SetId( ({ "sword", "short sword" }) );
11 SetAdjectives( ({ "short" }) );
12 SetShort("a plain sword");
13 SetLong("A cheap and rather dull short sword.");
14 SetMass(150);
15 SetHands(1);
16 SetDollarCost(50);
17 SetVendorType(VT_WEAPON);
18 SetClass(20);
19 SetDamageType(BLADE);
20 SetWeaponType("blade");
21 }
:x exited and saved
"/realms/cratylus/area/weap/sword.c" 21 lines 476 bytes
Exit from ed.
First I deleted lines 1 through 5 with the command '1,5d'.
Then, for good measure, I removed the remaining blank line '1d'.
Voila. Cleaner code.
REPLACING STRINGS
Well now I want to replace all instances of "short" with
"plain", and I don't feel like editing each matching line
manually. I can do a search and replace. First I will list which
lines need to change, then I will change them:
> ed sword.c
/realms/cratylus/area/weap/sword.c, 476 bytes
:n enabled line number printing
number on, list off
:g/short/p searched for and displayed lines containing "short"
10 SetId( ({ "sword", "short sword" }) );
11 SetAdjectives( ({ "short" }) );
13 SetLong("A cheap and rather dull short sword.");
:g/short/s/short/plain searched for "short" and replaced with "plain"
:g/short/p searched for "short" again but found none
:1z listed file from line 1
1 #include <lib.h>
2 #include <damage_types.h>
3 #include <vendor_types.h>
4
5 inherit LIB_ITEM;
6
7 static void create() {
8 item::create();
9 SetKeyName("plain sword");
10 SetId( ({ "sword", "plain sword" }) );
11 SetAdjectives( ({ "plain" }) );
12 SetShort("a plain sword");
13 SetLong("A cheap and rather dull plain sword.");
14 SetMass(150);
15 SetHands(1);
16 SetDollarCost(50);
17 SetVendorType(VT_WEAPON);
18 SetClass(20);
19 SetDamageType(BLADE);
20 SetWeaponType("blade");
21 }
:1 moved to line 1
1 #include <lib.h>
:I ran automatic indentation
Indenting entire code...
Indentation complete.
:1z listed file from line 1
#include <lib.h>
#include <damage_types.h>
#include <vendor_types.h>
inherit LIB_ITEM;
static void create() {
item::create();
SetKeyName("plain sword");
SetId( ({ "sword", "plain sword" }) );
SetAdjectives( ({ "plain" }) );
SetShort("a plain sword");
SetLong("A cheap and rather dull plain sword.");
SetMass(150);
SetHands(1);
SetDollarCost(50);
SetVendorType(VT_WEAPON);
SetClass(20);
SetDamageType(BLADE);
SetWeaponType("blade");
}
:x exited and saved
"/realms/cratylus/area/weap/sword.c" 21 lines 488 bytes
Exit from ed.
The command g/short/p showed me all the lines
that contained the substring "short". Then I ran the global
search and replace command to substitute "plain" for "short",
:g/short/s/short/plain
Then I searched again for the string "short" and
nothing came up, because it had been replaced.
Finally I went to line number 1 and issued the 'I'
command. This auto-indents the code, making it neater and
easier to read.
Editor basics, part 3
Now let's look at some common problems:
1) Accidental deletion
If you type 1,20d when you meant to type 1,2d you will end
up with a file 18 lines shorter than you intended. ed does not
have an "undo" command, so those lines will never come back.
However, if you quit the editor *without saving*, then that
deletion will not be committed to the file. You can issue the 'Q'
command:
:Q
To force quit without saving. Of course, if those lines
weren't already in the file, this won't help much.
2) Can't leave the editor
You try to write and exit, but get this:
:x
File command failed.
What this means is that for some reason, you can't write
to the file, so you don't exit the editor. What this usually means is that
you tried to edit a file that does not belong to you. Since you do not
have permission to modify the file, ed refuses to commit your changes.
There are two ways around this. If you don't really care
whether your changes are saved or not, you can just force quit the
editor with 'Q':
:Q
Exit from ed.
Your changes will be lost, but you'll be out of the editor.
If you really want to save this file, you'll have to save it
somewhere other than your current working directory (cwd). You can save
it to your home directory with the 'w' command, then force quit:
:w /realms/cratylus/sword.c
"/realms/cratylus/sword.c" 20 lines 478 bytes
:Q
Exit from ed.
3) Indent command fails
You try to auto-indent your code but get an error like this:
:I
Indenting entire code...
Unterminated string in line 13
Indentation halted.
This is pretty self explanatory. Indent relies on a certain
amount of coherence in your code, and if your syntax is sufficiently
munged, it can't figure out how to properly do its thing.
Examine the line that indent complains about, and also the
line before it. Sometimes a good line is accused of being bad, just
because it comes after a bad line.
4) I need to [something] in ed, but don't know how!
While in command mode, type 'h' and enter. You'll get
a handy list of ed commands available to you.
5) My ability/patience/time is limited. I want not to use ed.
I feel your pain. The currently available ways around
this are:
1) Shell account. If you can get shell, or command line access
to the computer that is running the mud, then you can probably
use an editor local to that computer (like vim) to edit files.
Chances are, though, that if you are a regular rank-and-file
creator, you will not be given shell access. Most system admins
consider giving random people off the net shell access
an abomination.
2) Server FTP/SFTP. The server that runs the mud might have an
ftp server or sftpd access. Again, most security-conscious sysadmins
will not permit Just Some Person Off The Internet to have this
kind of access.
3) Mud FTP. I don't like this option. Unix FTPD is a security
concern as it is. Using unsupported, un-warrantied mud network code
to provide ftp access to files seems to me to be equivalent to pulling
down your pants, bending over, and whistling for the Internet to
come visit. But...it's an option.
4) Client upload. This is actually the most sensible option, if
you are truly allergic to ed. You still need to use ed, but what
you can do is write your code in your favorite local editor, like
notepad or gvim or whatever. Then use your mud client (most of them
have an option to "send text") to send the code by running ed,
entering input mode, copying the code from your editor, and
pasting it into your client.
This is a somewhat awkward system, and ill-suited to
making minor changes. But it has the virtue of working well and
being a widely available option.
5) Suck it up. Really, you need to just get used to it. Don't
make me tell you stories about how when I was younger I had to
code using a VT terminal with no cut-and-paste, in an unheated,
locked computer lab 20'x10' in size, at 9600 bps. In a snowstorm.
Uphill both ways.
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