Vim

Useful commands.

Switch to last file

:e#

yank buffers

Copy data to different buffers.

vi /etc/{passwd,group,shadow} /tmp/newfile
"a2yy       # Yank two lines to yank buffer a.
:n          # Go to next file.
"b2yy
:n
#c2yy
:n
"ap         # paste yank buffer a. 
"bp
"cp

Delete lines and add to a buffer.

vi /tmp/tmp1 /tmp/tmp2
"add         # Delete some lines and add to buffer a.
"Add        # Go to next lines and add lines to buffer a.
:wn
"ap         # Paste buffer.

Deleted lines atomically get numbered buffers.

"2p         # Get back the deletion you did before this one.

filter

Sort part of file.

:96,99!sort # will pass lines 96 through 99 through the sort filter and replace those lines with the output of sort.