Section 12.
Linux editors.
"Vi has
two modes. The one in which it beeps and the one in which it
doesn’t."
Unknown.
12. Linux editors.
There are any number of editors
available in Linux. For systems hackers and programmers the
choice was often made between emacs or vi.
As more users came to the UNIX /
Linux environment from Windows they tended to be unwilling
to learn the command structure of editors like vi and
looked for more intuitive alternatives which made greater
use of the PC’s extended keyboard.
12.1. Pico
Pico became popular
through its use with the pine mail user agent.
12.2. Nano
The default editor in Ubuntu is
nano, a clone of pico which the Ubuntu man
pages describes as "non free". That’s a
swipe at the licence used by Washington University rather
than indicating that a charge is made for Pico’s
use.
12.3. Editors to shake a stick at.
Use a search engine to find some
of the available editors in Ubuntu. These include
12.4. ed, ex and vi.
In the beginning there was
ed. The ed line editor was written in PDP
11/20 assembler in 1971 by Ken Thompson and was one of the
first software tools created for the UNIX operating
system.
Aspects of ed were
included in ex which became one of the engines in the
visual editor vi.
Every Linux systems
administrator should know the basic ed commands and
be able to bail out systems that are otherwise unusable at
the command line. It is also useful to be able to
incorporate ed in here scripts. (Here
scripts are those where the input redirection is from the
script itself rather than an external file.)
The syntax of ed is very
simple and it takes only a few minutes to learn the
basics.
12.5. Example.
sa101# cd /etc
sa101$ head -7 shadow
root:$1$0OzJEaEY$D55n1EnPIPaOK8u0RU89D/:15137:0:::::
bin:*:9797:0:::::
daemon:*:9797:0:::::
adm:*:9797:0:::::
lp:*:9797:0:::::
sync:*:9797:0:::::
shutdown:*:9797:0:::::
sa101# ed shadow
778 #<- number of characters in the file
1s/:[^:]*:/::/ #<- go to line1. Substitute the first expression by the second
w #<- write the file back to disc
744 #<- number of characters written back to file
q #<- quit
sa101$ head -7 shadow
root::15137:0:::::
bin:*:9797:0:::::
daemon:*:9797:0:::::
adm:*:9797:0:::::
lp:*:9797:0:::::
sync:*:9797:0:::::
shutdown:*:9797:0:::::
12.6. Using vi.
Vi is the standard System V text
editor. It is installed by default on every host based
system V UNIX, including all Linux distributions, that I
have come across. It is not available as standard in Android
although implementations are downloadable.
True vi binaries are not
normally found on Linux distributions. Enhanced alternatives
are vim, elvis, nvi and vile.
The anecdotal evidence would suggest that Vim (Vi IMproved)
has become the dominant incarnation in the Linux world.
"Over the
years since its creation by Bill Joy, vi became the de facto
standard Unix editor and a nearly undisputed hacker
favourite outside of MIT, until the rise of Emacs after
about 1984. The Single UNIX Specification specifies
vi, so.. [ it must be included with every conformant
system.].. vi is still widely used by users of the
Unix family of operating systems. About half the respondents
in a 1991 USENET poll preferred vi. /In 1999, Tim
O’Reilly, founder of the eponymous computer book
publishing company, stated that his company sold more copies
of its vi book than its emacs book.
A 2009 survey
of Linux Journal readers found that vi was the most widely
used text editor among respondents, beating gedit,
the second most widely used editor by nearly a factor of two
(36% to 19%)." Wikipedia 2012.
A table of the more common
vi commands can be found overleaf.
12.7. Vi commands
12.8. Exercises.
Complete the training offered by
the tutor vimtutor.
