eshell pipelines (Was: Re: Optimal emacs shell for coding)

eshell pipelines (Was: Re: Optimal emacs shell for coding)

[David Hansen]

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[For emacs-devel: 

In gnu.emacs.help there is a discussion about some little eshell,
eshell/ls bug.  Processes in a pipeline get a TTY for IO (via
`start-process').  Quite some programs behave different whether they
have a TTY or not. 

The other thing is that eshell/ls does not output one file per line
when in a pipeline (as the usual GNU ls does).]

On Wed, 13 Aug 2008 13:21:00 +0200 Thierry Volpiatto wrote:

> As Lennart said you call ls with -1 arg or you can always call ls with
> this arg setting it like that:
>
> ,----
> | (setq eshell-ls-initial-args '(-1)) 
> `----
>
> now when you call for example "ls | wc -l" , you will have the
> good number of lines.
>
> It would be cool to have a function to call in some hook to call ls -1
> only if there is a "|" after ls, this function do that but i need a hook
> to call it:
>
> ,----
> | (defun eshell-set-ls ()
> |   (let ((com-line
> |          (eshell-parse-arguments (re-search-backward "ls") (line-end-position))))
> |     (if (equal (nth 1 com-line) '(eshell-operator "|"))
> |         (setq eshell-ls-initial-args '(-1))
> |         (setq eshell-ls-initial-args nil))))
> `----

Try the attached patch.  It

 * Starts subprocesses in a (eshell) pipeline using a pipe and not a TTY
   (this should also give some performance boost).

 * Appends "-1" to eshell/ls if ls is called in a pipeline.

At the time it's feature freeze for Emacs so it will probably take some
time to make it in there.  Cc: anyways, maybe some old timer can approve
the two lines.


David


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*** em-ls.el.~1.33.~	2008-06-07 20:14:50.000000000 +0200
--- em-ls.el	2008-08-13 14:05:43.000000000 +0200
***************
*** 299,304 ****
--- 299,306 ----
    (let ((insert-func 'eshell-buffered-print)
  	(error-func 'eshell-error)
  	(flush-func 'eshell-flush))
+     ;; In pipelines use the -1 switch.
+     (and eshell-in-pipeline-p (push "-1" args))
      (eshell-do-ls args)))
  
  (put 'eshell/ls 'eshell-no-numeric-conversions t)
*** esh-proc.el.~1.21.~	2008-05-12 20:30:41.000000000 +0200
--- esh-proc.el	2008-08-13 14:20:38.000000000 +0200
***************
*** 249,260 ****
  	 proc decoding encoding changed)
      (cond
       ((fboundp 'start-process)
!       (setq proc
! 	    (apply 'start-process
! 		   (file-name-nondirectory command) nil
! 		   ;; `start-process' can't deal with relative
! 		   ;; filenames
! 		   (append (list (expand-file-name command)) args)))
        (eshell-record-process-object proc)
        (set-process-buffer proc (current-buffer))
        (if (eshell-interactive-output-p)
--- 249,262 ----
  	 proc decoding encoding changed)
      (cond
       ((fboundp 'start-process)
!       ;; Don't use a TTY for processes in a pipeline.
!       (let ((process-connection-type (not eshell-in-pipeline-p)))
!         (setq proc
!               (apply 'start-process
!                      (file-name-nondirectory command) nil
!                      ;; `start-process' can't deal with relative
!                      ;; filenames
!                      (append (list (expand-file-name command)) args))))
        (eshell-record-process-object proc)
        (set-process-buffer proc (current-buffer))
        (if (eshell-interactive-output-p)

Re: eshell pipelines

[Glenn Morris]

David Hansen wrote:

> [For emacs-devel: 
>
> In gnu.emacs.help there is a discussion about some little eshell,
> eshell/ls bug. 

http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=699

(now on three separate mailing lists...)

Re: eshell pipelines

[David Hansen]

On Wed, 13 Aug 2008 12:09:07 -0400 Glenn Morris wrote:

> David Hansen wrote:
>
>> [For emacs-devel: 
>>
>> In gnu.emacs.help there is a discussion about some little eshell,
>> eshell/ls bug. 
>
> http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=699
>
> (now on three separate mailing lists...)

I find gmane.emacs.bug incredible "hard" to read.  Threads seem to
randomly stop and start again (w/o gnus finding the parents) and purely
administrative messages pop up every now and then.

Back to the topic:  not giving the pipelined processes a TTY will
prevent similar problems w/ non eshell builtins.  And in most cases it
should be faster as well, e.g. GNU libc uses line buffering on a TTY.

But probably we should first find a way to disable this for the last
command in the pipeline.  This is already done in
`eshell-do-pipelines-synchronously' (do we really need compat code for
Emacsen w/o `start-process'?).  I'll try to figure out how to do it
right.

David