Diferencias Entre Shells

DIFERENCIAS ENTRE SHELLS

FUENTE: http://www.faqs.org/faqs/unix-faq/shell/shell-differences/

VISITA: 2012 /MAR/ 12

The following article answers the frequently asked questions, what
UNIX shells are available, what are the differences between them and
howdo you change your interactive shell. It is posted monthly to the
USENET newsgroups comp.unix.shell, comp.unix.questions, news.answers
and comp.answers and is additionally available on the world wide web
as http://www.wonderland.org/~eternal/shell.html

Contents* Modifications since last issue
* Why change your shell
* The history of unix shells
* Deciding on a shell
* Shell features (table)
* How to change your shell
* A warning about changing your shell
* Further information
*Copyright and Disclaimer

Modifications since last issue

* Change of authors contact addresses

Why change your shell

The UNIX shell is most people's main access to the UNIX operating
system and as such any improvement toit can result in considerably
more effective use of the system, and may even allow you to do things
you couldn't do before. The primary improvement most of the new
generation shells give you is increased speed. They require fewer key
strokes to get the same results due to their completion features, theygive you more information (e.g. showing your directory in your prompt,
showing which files it would complete) and they cover some of the more
annoying features of UNIX, such as not going back up symbolic links to
directories.

A brief history of UNIX shellsNote, this history is just known to be slightly out of historical
order, it is in the process of being corrected, but for the moment
should be taken with a pinch of salt

In the near beginning there was the Bourne shell /bin/sh (written by
S. R. Bourne). It had (and still does) a very strong powerfulsyntactical language built into it, with all the features that are
commonly considered to produce structured programs; it has
particularly strong provisions for controlling input and output and in
its expression matching facilities. But no matter how strong its input
language is, it had one majordrawback; it made nearly no concessions
to the interactive user (the only real concession being the use of
shell functions and these were only added later) and so there was a
gap for something better.

Along came the people from UCB and the C-shell /bin/csh was born. Into
thisshell they put several concepts which were new, (the majority of
these being job control and aliasing) and managed to produce a shell
that was much better for interactive use. But as well as improving the
shell for interactive use they also threw out the baby with the bath
water and went for a different input language....