Text editors in an xterm
vi (vim or elvis on some unixes) Unpleasant, but fast and ubiquitous. preferred for/by admin
"modal" :command mode and input mode

 x      delete character
 dd     delete line
 :wq    save changes and exit  : means an ed command
 :q!    quit, do not save changes
 i  go into input mode (insert)
 a  go into input mode (append)
 o  go into input mode (open new line)
If arrow keys don't move cursor: h i j k do.

Get out of input mode (back to command mode) with Esc.
Other useful vi commands (among hundreds):
:$      goto end of file
:r fil1     import file
:j      join two lines together
#yy     yank # lines to buffer
p       paste buffer contents
^f      ctrl f  scroll forward page
^b      scroll back
gvim X-enabled.
ed line editor.

the ne plus ultra of editors.
GUI, X-enabled
emacs -nw to run in an xterm
source code formatting "IDE"
extensible (has built-in Lisp system for creating commands, binding to keystrokes)
email reader, ange-ftp, news reader, file manager, run a shell inside emacs.
Always in input mode. Menu-driven commands (icons in xemacs), or keyboard are issued by holding Control or Alt.
Cursor movement by arrow keys, Home, End, Page Up, Page Down.
But if those keys don't work on your system (it's configurable):

up line      ^P  (means holding Ctrl, press lowercase p)
down line    ^N
beginning  line  ^A
end of line  ^E
down page    ^V
up page M-V   (means holding Alt, press lowercase v)
              M is 'meta' (emacs jargon). Might be press and release
             Esc on some sYstems.
Deleting text:
char        ^D or maybe Delete.  Backspace deletes char to left of
line        ^K
word        M-D 
A group of lines that was just deleted can be pasted by ^Y
Save changes     ^XS  holding Control, press x then s
Quit         ^XC
Load a file  ^XF  will be prompted for name of file
Insert a file   ^X i  (means do ^X followed by i, without holding ctrl)
Undo         ^X u
Cancel       ^G  to stop some inadvertant command
reformat paragraph   M-Q
switch to other buffer  ^X b
one buffer only         ^X 1
hundreds of other commands, including Eliza psychotherapist (M-X doctor)
Emacs configuration file: ~/.emacs
For a better looking emacs, edit your .Xdefaults file to change some of its emacs lines to:
emacs*geometry: 80x30+0+15
emacs*font: 9x15bold