Aug 182012
General Startup
	To use vi: vi filename
	To exit vi and save changes: ZZ   or  :wq
	To exit vi without saving changes: :q!
	To enter vi command mode: [esc]

        A number preceding any vi command tells vi to repeat
	that command that many times.

Cursor Movement

	h       move left (backspace)

	j       move down

	k       move up

	l       move right (spacebar)

	[return]   move to the beginning of the next line

	$       last column on the current line

	0       move cursor to the first column on the
		current line

	^       move cursor to first nonblank column on the
		current line

	w       move to the beginning of the next word or
		punctuation mark

	W       move past the next space

	b       move to the beginning of the previous word
		or punctuation mark

	B       move to the beginning of the previous word,
		ignores punctuation

        e       end of next word or punctuation mark

        E       end of next word, ignoring punctuation

        H       move cursor to the top of the screen 

        M       move cursor to the middle of the screen

        L       move cursor to the bottom of the screen 

Screen Movement

       G        move to the last line in the file

       xG       move to line x

       z+       move current line to top of screen

       z        move current line to the middle of screen

       z-       move current line to the bottom of screen

       ^F       move forward one screen

       ^B       move backward one line

       ^D       move forward one half screen

       ^U       move backward one half screen

       ^R       redraw screen
		( does not work with VT100 type terminals )

       ^L       redraw screen
		( does not work with Televideo terminals )


       r        replace character under cursor with next
		character typed

       R        keep replacing character until [esc] is hit

       i        insert before cursor

       a        append after cursor

       A        append at end of line

       O        open line above cursor and enter append mode


	x       delete character under cursor

	dd      delete line under cursor

        dw      delete word under cursor

        db      delete word before cursor

Copying Code

        yy      (yank)'copies' line which may then be put by
		the p(put) command. Precede with a count for
		multiple lines.

        :t.     will duplicate the line.

        :t 7    will copy it after line 7.

        :,+t0   will copy current and next line at the
        beginning of the file.

        :1,t$   will copy lines from beginning of the file
        to the current cursor position, to the end of the file.

Put Command
        brings back previous deletion or yank of lines,
	words, or characters

        P       bring back before cursor

        p       bring back after cursor

Find Commands

	?       finds a word going backwards

	/       finds a word going forwards

        f       finds a character on the line under the
		cursor going forward

        F       finds a character on the line under the
		cursor going backwards

        t       find a character on the current line going
		forward and stop one character before it

	T       find a character on the current line going
		backward and stop one character before it

	;	repeat last f, F, t, T

Find and Replace Commands

        :%s/hello/goodbye/g   find hello and replace with goodbye

        :%s/^\(.*\)\n\1$/g    delete duplicate lines

        :%s/\n/ /g            join lines together

Miscellaneous Commands

	.	repeat last command

	u	undo last command issued

	U	undoes all commands on one line

	xp	deletes first character and inserts after
		second (swap)

	J	join current line with the next line

	^G	display current line number

	%	if at one parenthesis, will jump to its mate

	mx	mark current line with character x

	'x	find line marked with character x

	NOTE: Marks are internal and not written to the file.

Line Editor Mode
	Any commands from the line editor ex can be issued
	upon entering line mode.

	To enter: type ':'

	To exit: press[return] or [esc]

ex Commands
	For a complete list consult the
	UNIX Programmer's Manual

	copies (reads) filename after cursor in file
	currently editing

	:r filename

	:w 	saves the current file without quitting
	:20,40w filename write the contents of the lines numbered 20 through 40 to
	a new file named filename

	:#	move to line #

	:$	move to last line of file

	executes 'cmd' as a shell command.


Jun 242010

Awk does a lot more than select a column from a file or an input stream. It can select columns from selected rows. It can calculate totals, extract substrings, reverse the order of fields and provide a whole lot of other very handy manipulations. Whether you squeeze your awk permutations onto the command line or prefer to build them into scripts, the language is clever and versatile and well worth using even as it joins the ranks of middle-aged computer utilities.

If you want to use awk to add up a bunch of numbers formulated as a column in a text file, you can use a one-liner like this:

$ awk ‘{ SUM+=$1 } END { print SUM }’ < nums
That SUM+= operation adds the contents of column one to a running total for each line of input. The sum is only printed at the very end when input is exhausted. You can change $1 to the column of your choice or $NF if you want to add up the rightmost column.

If you prefer scripts to the command line, you could use a script like the addcol script below to sum whatever column you choose. You would just pass the column you want to add on the command line as the COL parameter:

$ awk -f addcol COL=3 < numbers
The -f tells awk to run the designated script (addcol) and COL=3 passes “3” as the column number you want to sum.

# addcol
  print $COL
  SUM += $COL
END { print “Sum: ” SUM }
Awk has some grep-like features as well. If you want to operate only on lines that contain some particular text, you can specify that text on the command line like this:

$ awk ‘/choose me/’ textfile
You can also combine search options using && (and), || (or), and even negation operators. The command below selects lines that contain both the word “this” and the word “that”. Using ‘/this/ && !/that/’ would select only lines that contain “this” without containing “that”.

$ awk ‘/this/ && /that/’ notes
# find the process that started this one
# make sure that this user provided an answer
You can also select content based on its position within your input. In the command below, we only want to see lines eleven and above.

$ awk ‘NR > 10’ counts
11 63
12 99
13 63
14 77
15 41

And, of course, there are a lot of other nice little tricks available.

Awk provides some quick and effective filtering and incorporates an easy syntax. Probably the only thing that takes some getting used to is referring to parameters without putting dollar signs in front of them.

Obtained from