getting 'clear' to work in Emacs shell

[Oleksandr Gavenko]

On 18.10.2010 16:53, Jeff Rancier wrote:
> GNU Emacs 21.3.1 (i386-msvc-nt5.1.2600) of 2003-03-27 on buffy
> GNU bash, version 3.2.51(24)-release (i686-pc-cygwin)
> CYGWIN_NT-5.1 1.7.7(0.230/5/3) 2010-08-31 09:58
> Microsoft Windows XP Pro - Version 2002, SP3
>
> The 'clear' work's  in a Cygwin Bash session,
>
> C106426@USLINY2R86KRP8 ~
> $ alias  clear
> alias clear='cat ~/.cls'
>
> C106426@USLINY2R86KRP8 ~
> $ less  .cls
> ESC[2J
> .cls (END)
>
> But doesn't  within Emacs:
>
> C-z runs the command  shell
>     which is an interactive compiled Lisp function in `shell'.
> (shell&optional BUFFER)
>
> All I get within an  Emacs shell session is the following, without clearing the
> screen.  Is there  some envionment variable I need to set here?
>
>
> bash-3.2$  clear
> [2J
> bash-3.2$
>
As I understand you run M-x shell and type 'clear RET' and expect that
Emacs buffer cleared and contain only new prompt.

shell-mode does not designed to work as terminal.

Try use M-x term witch try emulate terminal behavior (thus allow run 
ncurses apps).

I run Emacs in 'mintty', type M-x term, I was asked for shell, select 
default '/bin/sh',
type RET and get prompt.

Under prompt type 'ls', get list of file, type 'clear', get error

sh-3.2$ clear
'eterm-color': unknown terminal type

next type 'export TERM=xterm RET' and 'clear'. I get 'sh-3.2$' prompt 
and all previous output
cleared.

As I understand that is you want.

shell-mode does  not understand terminal ESC sequences.

For example there exist special functions:

ansi-color-for-comint-mode-on
ansi-color-for-comint-mode-off

When you type in shell-mode 'ls --color' with ansi-color-for-comint-mode-off
you get such output:

^[[0m^[[01;34mApplication Data^[[0m  ^[[01;34mNetHood^[[0m 
^[[01;32mntuser.ini^[[0m  ^[[01;34mSendTo^[[0m      \
   ^[[01;34mМои документы^[[0m

When you type in shell-mode 'ls --color' with ansi-color-for-comint-mode-on
you get colorized output like in terminal:

Application Data  NetHood         ntuser.ini  SendTo        Мои документы


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