Re: Examining the output of a shell command?

[Raffaele Ricciardi <rfflrccrd@gmail.com>]

On 28/06/15 15:57, Pascal J. Bourguignon wrote:
 > (shell-command-to-string "echo $RED hello $NORMAL")
 > --> "[31m hello [0m> "

Hence, how could I capture a colorized output in Emacs as in a Bash
session?

Below is a Bash script that recursively searches "*.el" files for the
string "defun" and highlights matches (the complex `find` call is the
shell command generated by `M-x rgrep` for the same task):

     #!/bin/bash

     export GREP_COLORS="mt=01;31:fn=:ln=:bn=:se=:sl=:cx=:ne"
     export GREP_OPTIONS="--color=auto"
     find . -type d \( -path \*/SCCS -o -path \*/RCS -o -path \*/CVS -o 
-path \*/MCVS -o -path \*/.svn -o -path \*/.git -o -path \*/.hg -o -path 
\*/.bzr -o -path \*/_MTN -o -path \*/_darcs -o -path \*/\{arch\} \) 
-prune -o \! -type d \( -name \*_flymake.\* -o -name .\#\* -o -name \*.o 
-o -name \*\~ -o -name \*.bin -o -name \*.lbin -o -name \*.so -o -name 
\*.a -o -name \*.ln -o -name \*.blg -o -name \*.bbl -o -name \*.elc -o 
-name \*.lof -o -name \*.glo -o -name \*.idx -o -name \*.lot -o -name 
\*.fmt -o -name \*.tfm -o -name \*.class -o -name \*.fas -o -name \*.lib 
-o -name \*.mem -o -name \*.x86f -o -name \*.sparcf -o -name \*.dfsl -o 
-name \*.pfsl -o -name \*.d64fsl -o -name \*.p64fsl -o -name \*.lx64fsl 
-o -name \*.lx32fsl -o -name \*.dx64fsl -o -name \*.dx32fsl -o -name 
\*.fx64fsl -o -name \*.fx32fsl -o -name \*.sx64fsl -o -name \*.sx32fsl 
-o -name \*.wx64fsl -o -name \*.wx32fsl -o -name \*.fasl -o -name 
\*.ufsl -o -name \*.fsl -o -name \*.dxl -o -name \*.lo -o -name \*.la -o 
-name \*.gmo -o -name \*.mo -o -name \*.toc -o -name \*.aux -o -name 
\*.cp -o -name \*.fn -o -name \*.ky -o -name \*.pg -o -name \*.tp -o 
-name \*.vr -o -name \*.cps -o -name \*.fns -o -name \*.kys -o -name 
\*.pgs -o -name \*.tps -o -name \*.vrs -o -name \*.pyc -o -name \*.pyo 
\) -prune -o -type f \( -iname \*.el \) -exec grep -i -n -e defun 
/dev/null {} +

I have tested the above Bash script with `bash --noprofile --norc` as
well, to disable any initialization.  As far as i can tell, Emacs is
running Bash -- `(getenv "SHELL")` returns "/bin/bash" -- without any
initialization scripts -- `(getenv "BASH_ENV")` returns `nil`.

Below is an Emacs Lisp function that returns the output of the same
shell command as a string:

     (defun emacs-grep-test ()
       "Return the output of the `grep` program."
       (let ((process-environment (copy-list process-environment)))
         (setenv "GREP_COLORS" "mt=01;31:fn=:ln=:bn=:se=:sl=:cx=:ne")
         (setenv "GREP_OPTIONS" "--color=auto")
         (shell-command-to-string "find . -type d \\( -path \\*/SCCS -o 
-path \\*/RCS -o -path \\*/CVS -o -path \\*/MCVS -o -path \\*/.svn -o 
-path \\*/.git -o -path \\*/.hg -o -path \\*/.bzr -o -path \\*/_MTN -o 
-path \\*/_darcs -o -path \\*/\\{arch\\} \\) -prune -o \\! -type d \\( 
-name \\*_flymake.\\* -o -name .\\#\\* -o -name \\*.o -o -name \\*\\~ -o 
-name \\*.bin -o -name \\*.lbin -o -name \\*.so -o -name \\*.a -o -name 
\\*.ln -o -name \\*.blg -o -name \\*.bbl -o -name \\*.elc -o -name 
\\*.lof -o -name \\*.glo -o -name \\*.idx -o -name \\*.lot -o -name 
\\*.fmt -o -name \\*.tfm -o -name \\*.class -o -name \\*.fas -o -name 
\\*.lib -o -name \\*.mem -o -name \\*.x86f -o -name \\*.sparcf -o -name 
\\*.dfsl -o -name \\*.pfsl -o -name \\*.d64fsl -o -name \\*.p64fsl -o 
-name \\*.lx64fsl -o -name \\*.lx32fsl -o -name \\*.dx64fsl -o -name 
\\*.dx32fsl -o -name \\*.fx64fsl -o -name \\*.fx32fsl -o -name 
\\*.sx64fsl -o -name \\*.sx32fsl -o -name \\*.wx64fsl -o -name 
\\*.wx32fsl -o -name \\*.fasl -o -name \\*.ufsl -o -name \\*.fsl -o 
-name \\*.dxl -o -name \\*.lo -o -name \\*.la -o -name \\*.gmo -o -name 
\\*.mo -o -name \\*.toc -o -name \\*.aux -o -name \\*.cp -o -name \\*.fn 
-o -name \\*.ky -o -name \\*.pg -o -name \\*.tp -o -name \\*.vr -o -name 
\\*.cps -o -name \\*.fns -o -name \\*.kys -o -name \\*.pgs -o -name 
\\*.tps -o -name \\*.vrs -o -name \\*.pyc -o -name \\*.pyo \\) -prune -o 
-type f \\( -iname \\*.el \\) -exec grep -i -n -e defun /dev/null {} +")))

However, the string returned by `M-: (emacs-grep-test) RET` does not
contain escape sequences to colorize the output, as I would expect.