Hello,
Here is the content of my file ~/.profile :

export PATH=$HOME/context/tex/texmf-linux-64/bin:$PATH
export PATH=$HOME/texlive/2018/bin/x86_64-linux:$PATH
export PATH=$HOME/bin:$PATH

$ command -v context

 [aragorn@fab ~]$  command -v context
/home/aragorn/texlive/2018/bin/x86_64-linux/context
[aragorn@fab ~]$

I then tested the vladimir.tex file



\setupsynctex[state=start]

\startusableMPgraphic{NumberHead}
  draw outlinetext.f
  ("\bf\namedheadnumber{chapter}")
  (withcolor "blue")
  ysized 50pt ;
\stopusableMPgraphic

\unexpanded\def\processMPheadnumber#1%
  {\useMPgraphic{NumberHead}}

\setuphead%
[chapter]%
[command=\HeadTitle,%
 headstyle=\ss,%
 numbercommand=\processMPheadnumber]

\unexpanded\def\HeadTitle#1#2%
{\framed%
  [frame=off,%
    bottomframe=on,%
    width=broad,
    align={broad,nothyphenated,left}]%
{#1\blank[nowhite]#2}}

\starttext
\startchapter[title=First chapter]
  \input ward
\stopchapter
\stoptext
~/

% Local Variables:
% mode: context
% TeX-master: t
% End:

Here is the output vladimi
r
.output


Running `ConTeXt' on `vladimir' with ``PATH=/home/aragorn/context/tex/texmf-linux-64/bin:$PATH context --purgeall vladimir''
resolvers       | trees | analyzing 'home:texmf'
mtx-context     | warning: no (local) file './vladimir', proceeding
mtx-context     | run 1: luatex --fmt="/home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en" --jobname="vladimir" --lua="/home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en.lui" --no-parse-first-line --c:currentrun=1 --c:fulljobname="./vladimir" --c:input="./vladimir" --c:kindofrun=1 --c:maxnofruns=9 --c:purgeall "cont-yes.mkiv"

This is LuaTeX, Version 1.08.0 (TeX Live 2018)
 system commands enabled.

resolvers       > trees > analyzing 'home:texmf'
open source     > level 1, order 1, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv'
system          >
system          > ConTeXt  ver: 2018.08.25 10:04 MKIV beta  fmt: 2018.8.25  int: english/english
system          >
system          > 'cont-new.mkiv' loaded
open source     > level 2, order 2, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system          > beware: some patches loaded from cont-new.mkiv
close source    > level 2, order 2, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system          > files > jobname 'vladimir', input './vladimir', result 'vladimir'
fonts           > latin modern fonts are not preloaded
languages       > language 'en' is active
open source     > level 2, order 3, name '/home/aragorn/vladimir.tex'
system          > synctex functionality is enabled, expect 5-10 pct runtime overhead!
fonts           > preloading latin modern fonts (second stage)
fonts           > 'fallback modern-designsize rm 12pt' is loaded
structure       > sectioning > chapter @ level 2 : 0.1 -> First chapter
metapost        > initializing instance 'metafun:1' using format 'metafun' and method 'default'
metapost        > loading 'metafun' as '/home/aragorn/context/tex/texmf-context/metapost/context/base/mpiv/metafun.mpiv' using method 'default'
metapost        > initializing number mode 'scaled'
open source     > level 3, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/sample/common/ward.tex'
close source    > level 3, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/sample/common/ward.tex'
backend         > xmp > using file '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/lpdf-pdx.xml'
pages           > flushing realpage 1, userpage 1, subpage 1
close source    > level 2, order 4, name '/home/aragorn/vladimir.tex'
close source    > level 1, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv'

mkiv lua stats  > used config file: selfautoparent:/texmf/web2c/texmfcnf.lua
mkiv lua stats  > used cache path: /home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e
mkiv lua stats  > resource resolver: loadtime 0.008 seconds, 1 scans with scantime 0.000 seconds, 0 shared scans, 31 found files, scanned paths: /home/aragorn/texmf
mkiv lua stats  > stored bytecode data: 437 modules (0.227 sec), 93 tables (0.015 sec), 530 chunks (0.241 sec)
mkiv lua stats  > traced context: maxstack: 1328, freed: 5, unreachable: 1323
mkiv lua stats  > cleaned up reserved nodes: 58 nodes, 9 lists of 455
mkiv lua stats  > node memory usage: 2 glue, 2 kern, 2 penalty, 14 attribute, 50 glue_spec, 4 attribute_list, 2 temp, 2 user_defined
mkiv lua stats  > node list callback tasks: 8 unique task lists, 6 instances (re)created, 55 calls
mkiv lua stats  > synctex tracing: 2 referenced files, 5 files ignored, 3 objects flushed, logfile: vladimir.synctex
mkiv lua stats  > used backend: pdf (backend for directly generating pdf output)
mkiv lua stats  > jobdata time: 0.001 seconds saving, 0.000 seconds loading
mkiv lua stats  > callbacks: internal: 177, file: 180, direct: 2, late: 2, function 534, total: 895
mkiv lua stats  > loaded patterns: en::2, load time: 0.000
mkiv lua stats  > result saved in file: vladimir.pdf, compresslevel 3, objectcompresslevel 3
mkiv lua stats  > loaded fonts: 4 files: latinmodern-math.otf, lmroman10-bold.otf, lmroman10-regular.otf, lmroman12-regular.otf
mkiv lua stats  > font engine: otf 3.104, afm 1.513, tfm 1.000, 9 instances, 3 shared in backend, 3 common vectors, 0 common hashes, load time 0.216 seconds
mkiv lua stats  > metapost: 0.001 seconds, loading: 0.017, execution: 0.001, n: 1, average: 0.019, instances: 1, luacalls: 8, memory: 2.635 M
mkiv lua stats  > used platform: linux-64, type: unix, binary subtree: texmf-linux-64
mkiv lua stats  > used engine: luatex version 1.08 with functionality level 6731, banner: this is luatex, version 1.08.0 (tex live 2018)
mkiv lua stats  > control sequences: 46537 of 65536 + 100000
mkiv lua stats  > lua properties: engine: lua 5.3, used memory: 81 MB (ctx: 81 MB), hash type: lua, hash chars: min(64,40), symbol mask: utf (τεχ)
mkiv lua stats  > runtime: 0.538 seconds, 1 processed pages, 1 shipped pages, 1.859 pages/second
mtx-context     | run 2: luatex --fmt="/home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en" --jobname="vladimir" --lua="/home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en.lui" --no-parse-first-line --c:currentrun=2 --c:fulljobname="./vladimir" --c:input="./vladimir" --c:kindofrun=2 --c:maxnofruns=9 --c:purgeall "cont-yes.mkiv"

This is LuaTeX, Version 1.08.0 (TeX Live 2018)
 system commands enabled.

resolvers       > trees > analyzing 'home:texmf'
open source     > level 1, order 1, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv'
system          >
system          > ConTeXt  ver: 2018.08.25 10:04 MKIV beta  fmt: 2018.8.25  int: english/english
system          >
system          > 'cont-new.mkiv' loaded
open source     > level 2, order 2, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system          > beware: some patches loaded from cont-new.mkiv
close source    > level 2, order 2, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system          > files > jobname 'vladimir', input './vladimir', result 'vladimir'
fonts           > latin modern fonts are not preloaded
languages       > language 'en' is active
open source     > level 2, order 3, name '/home/aragorn/vladimir.tex'
system          > synctex functionality is enabled, expect 5-10 pct runtime overhead!
fonts           > preloading latin modern fonts (second stage)
fonts           > 'fallback modern-designsize rm 12pt' is loaded
structure       > sectioning > chapter @ level 2 : 0.1 -> First chapter
metapost        > initializing instance 'metafun:1' using format 'metafun' and method 'default'
metapost        > loading 'metafun' as '/home/aragorn/context/tex/texmf-context/metapost/context/base/mpiv/metafun.mpiv' using method 'default'
metapost        > initializing number mode 'scaled'
open source     > level 3, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/sample/common/ward.tex'
close source    > level 3, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/sample/common/ward.tex'
backend         > xmp > using file '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/lpdf-pdx.xml'
pages           > flushing realpage 1, userpage 1, subpage 1
close source    > level 2, order 4, name '/home/aragorn/vladimir.tex'
close source    > level 1, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv'

mkiv lua stats  > used config file: selfautoparent:/texmf/web2c/texmfcnf.lua
mkiv lua stats  > used cache path: /home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e
mkiv lua stats  > resource resolver: loadtime 0.008 seconds, 1 scans with scantime 0.001 seconds, 0 shared scans, 31 found files, scanned paths: /home/aragorn/texmf
mkiv lua stats  > stored bytecode data: 437 modules (0.238 sec), 93 tables (0.015 sec), 530 chunks (0.253 sec)
mkiv lua stats  > traced context: maxstack: 1328, freed: 5, unreachable: 1323
mkiv lua stats  > cleaned up reserved nodes: 58 nodes, 9 lists of 455
mkiv lua stats  > node memory usage: 2 glue, 2 kern, 2 penalty, 14 attribute, 50 glue_spec, 4 attribute_list, 2 temp, 2 user_defined
mkiv lua stats  > node list callback tasks: 8 unique task lists, 6 instances (re)created, 55 calls
mkiv lua stats  > synctex tracing: 2 referenced files, 5 files ignored, 3 objects flushed, logfile: vladimir.synctex
mkiv lua stats  > used backend: pdf (backend for directly generating pdf output)
mkiv lua stats  > jobdata time: 0.001 seconds saving, 0.000 seconds loading
mkiv lua stats  > callbacks: internal: 177, file: 180, direct: 2, late: 2, function 534, total: 895
mkiv lua stats  > randomizer: initialized with value 0.55005725985393
mkiv lua stats  > loaded patterns: en::2, load time: 0.000
mkiv lua stats  > result saved in file: vladimir.pdf, compresslevel 3, objectcompresslevel 3
mkiv lua stats  > loaded fonts: 4 files: latinmodern-math.otf, lmroman10-bold.otf, lmroman10-regular.otf, lmroman12-regular.otf
mkiv lua stats  > font engine: otf 3.104, afm 1.513, tfm 1.000, 9 instances, 3 shared in backend, 3 common vectors, 0 common hashes, load time 0.227 seconds
mkiv lua stats  > metapost: 0.001 seconds, loading: 0.017, execution: 0.001, n: 1, average: 0.019, instances: 1, luacalls: 8, memory: 2.635 M
mkiv lua stats  > used platform: linux-64, type: unix, binary subtree: texmf-linux-64
mkiv lua stats  > used engine: luatex version 1.08 with functionality level 6731, banner: this is luatex, version 1.08.0 (tex live 2018)
mkiv lua stats  > control sequences: 46536 of 65536 + 100000
mkiv lua stats  > lua properties: engine: lua 5.3, used memory: 81 MB (ctx: 81 MB), hash type: lua, hash chars: min(64,40), symbol mask: utf (τεχ)
mkiv lua stats  > runtime: 0.562 seconds, 1 processed pages, 1 shipped pages, 1.779 pages/second
mtx-context     | run 3: luatex --fmt="/home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en" --jobname="vladimir" --lua="/home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en.lui" --no-parse-first-line --c:currentrun=3 --c:fulljobname="./vladimir" --c:input="./vladimir" --c:kindofrun=2 --c:maxnofruns=9 --c:purgeall "cont-yes.mkiv"

This is LuaTeX, Version 1.08.0 (TeX Live 2018)
 system commands enabled.

resolvers       > trees > analyzing 'home:texmf'
open source     > level 1, order 1, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv'
system          >
system          > ConTeXt  ver: 2018.08.25 10:04 MKIV beta  fmt: 2018.8.25  int: english/english
system          >
system          > 'cont-new.mkiv' loaded
open source     > level 2, order 2, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system          > beware: some patches loaded from cont-new.mkiv
close source    > level 2, order 2, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system          > files > jobname 'vladimir', input './vladimir', result 'vladimir'
fonts           > latin modern fonts are not preloaded
languages       > language 'en' is active
open source     > level 2, order 3, name '/home/aragorn/vladimir.tex'
system          > synctex functionality is enabled, expect 5-10 pct runtime overhead!
fonts           > preloading latin modern fonts (second stage)
fonts           > 'fallback modern-designsize rm 12pt' is loaded
structure       > sectioning > chapter @ level 2 : 0.1 -> First chapter
metapost        > initializing instance 'metafun:1' using format 'metafun' and method 'default'
metapost        > loading 'metafun' as '/home/aragorn/context/tex/texmf-context/metapost/context/base/mpiv/metafun.mpiv' using method 'default'
metapost        > initializing number mode 'scaled'
open source     > level 3, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/sample/common/ward.tex'
close source    > level 3, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/sample/common/ward.tex'
backend         > xmp > using file '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/lpdf-pdx.xml'
pages           > flushing realpage 1, userpage 1, subpage 1
close source    > level 2, order 4, name '/home/aragorn/vladimir.tex'
close source    > level 1, order 4, name '/home/aragorn/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv'

mkiv lua stats  > used config file: selfautoparent:/texmf/web2c/texmfcnf.lua
mkiv lua stats  > used cache path: /home/aragorn/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e
mkiv lua stats  > resource resolver: loadtime 0.007 seconds, 1 scans with scantime 0.000 seconds, 0 shared scans, 31 found files, scanned paths: /home/aragorn/texmf
mkiv lua stats  > stored bytecode data: 437 modules (0.217 sec), 93 tables (0.015 sec), 530 chunks (0.232 sec)
mkiv lua stats  > traced context: maxstack: 1328, freed: 5, unreachable: 1323
mkiv lua stats  > cleaned up reserved nodes: 58 nodes, 9 lists of 455
mkiv lua stats  > node memory usage: 2 glue, 2 kern, 2 penalty, 14 attribute, 50 glue_spec, 4 attribute_list, 2 temp, 2 user_defined
mkiv lua stats  > node list callback tasks: 8 unique task lists, 6 instances (re)created, 55 calls
mkiv lua stats  > synctex tracing: 2 referenced files, 5 files ignored, 3 objects flushed, logfile: vladimir.synctex
mkiv lua stats  > used backend: pdf (backend for directly generating pdf output)
mkiv lua stats  > jobdata time: 0.001 seconds saving, 0.000 seconds loading
mkiv lua stats  > callbacks: internal: 177, file: 180, direct: 2, late: 2, function 534, total: 895
mkiv lua stats  > randomizer: resumed with value 0.55005725985393
mkiv lua stats  > loaded patterns: en::2, load time: 0.000
mkiv lua stats  > result saved in file: vladimir.pdf, compresslevel 3, objectcompresslevel 3
mkiv lua stats  > loaded fonts: 4 files: latinmodern-math.otf, lmroman10-bold.otf, lmroman10-regular.otf, lmroman12-regular.otf
mkiv lua stats  > font engine: otf 3.104, afm 1.513, tfm 1.000, 9 instances, 3 shared in backend, 3 common vectors, 0 common hashes, load time 0.221 seconds
mkiv lua stats  > metapost: 0.001 seconds, loading: 0.018, execution: 0.001, n: 1, average: 0.019, instances: 1, luacalls: 8, memory: 2.635 M
mkiv lua stats  > used platform: linux-64, type: unix, binary subtree: texmf-linux-64
mkiv lua stats  > used engine: luatex version 1.08 with functionality level 6731, banner: this is luatex, version 1.08.0 (tex live 2018)
mkiv lua stats  > control sequences: 46536 of 65536 + 100000
mkiv lua stats  > lua properties: engine: lua 5.3, used memory: 86 MB (ctx: 85 MB), hash type: lua, hash chars: min(64,40), symbol mask: utf (τεχ)
mkiv lua stats  > runtime: 0.536 seconds, 1 processed pages, 1 shipped pages, 1.866 pages/second
mtx-context     | purged files: vladimir.log, vladimir.tuc
system          | total runtime: 2.525 seconds


TeX Output finished at Wed Aug 29 11:54:03

Could you show in full your ~/.emacs file? Do you use AUCTeX or bare
Emacs
?

I use AUCTEX but I d not know bare Emacs

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(ConTeXt-Mark-version "IV")
 '(ConTeXt-engine "luatex")
 '(TeX-command-extra-options "-shell-escape")
 '(ansi-color-faces-vector
   [default default default italic underline success warning error])
 '(ansi-color-names-vector
   ["#242424" "#e5786d" "#95e454" "#cae682" "#8ac6f2" "#333366" "#ccaa8f" "#f6f3e8"])
 '(custom-enabled-themes (quote (leuven)))
 '(package-selected-packages
   (quote
    (yasnippet-snippets auto-complete-auctex context-coloring nova-theme auctex)))
 '(tab-width 4))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 )

;; SERVER Download (MELPA):

(when (>= emacs-major-version 24)
  (require 'package)
  (add-to-list
   'package-archives
   '("melpa" . "http://melpa.org/packages/")
   t))
 

(eval-after-load "context"
  '(setq TeX-command-list
       (cons '("ConTeXt" "PATH=/home/aragorn/context/tex/texmf-linux-64/bin:$PATH context --purgeall %s"
         TeX-run-command nil t :help "Run context (MarkIV)") TeX-command-list))
)


;;(add-hook 'ConTeXt-mode-hook
          ;;(lambda()
          ;;  (setq TeX-command-default "ConTeXt Full")))

(setq-default cursor-type 'bar)

(set-cursor-color "#ff0000")


(setq TeX-view-program-list '(("Evince" "evince %o"))
      TeX-view-program-selection '((output-pdf "Evince")))

(setq make-backup-files nil) ; stop creating backup~ files
(setq auto-save-default nil) ; stop creating #autosave# files

;; auto close bracket insertion. New in emacs 24
(electric-pair-mode 1)

;; turn on highlight matching brackets when cursor is on one
(show-paren-mode 1)


(setq inhibit-startup-screen t)


(add-to-list 'load-path "/home/aragorn/texlive/2018/texmf-dist/asymptote")
(autoload 'asy-mode "asy-mode.el" "Asymptote major mode." t)
(autoload 'lasy-mode "asy-mode.el" "hybrid Asymptote/Latex major mode." t)
(autoload 'asy-insinuate-latex "asy-mode.el" "Asymptote insinuate LaTeX." t)
(add-to-list 'auto-mode-alist '("\\.asy$" . asy-mode))

(setq column-number-mode t)

(setq line-number-mode t)


(setq py-install-directory "~/.emacs.d/site-lisp/python-mode.el-6.1.1")

(add-to-list 'load-path py-install-directory)

(require 'python-mode)

;;(add-hook 'ConTeXt-mode-hook
          ;;(lambda ()
           ;; (setq indent-tabs-mode t
                ;;  indent-line-function 'indent-relative)))

(add-hook 'LaTeX-mode-hook
          (lambda()
             (add-to-list 'TeX-command-list '("LuaTeX" "%`lualatex%(mode)%' %t" TeX-run-TeX nil t))
             (setq TeX-command-default "LuaTeX")
             (setq TeX-save-query nil)
             (setq TeX-show-compilation t)))


(setq-default TeX-engine 'luatex
              TeX-PDF-mode t)
Thanks
Fabrice


Le mer. 29 août 2018 à 11:39, Fabrice Couvreur <fabrice1.couvreur@gmail.com> a écrit :
Hello,
Before considering modifications, here's what I get when I do which context :

Setting "/home/aragorn/context/tex" as ConTeXt root.
[aragorn@fab ~]$ which context
/home/aragorn/context/tex/texmf-linux-64/bin/context
[aragorn@fab ~]$

$ pacman -Qs texlive

 [root@fab aragorn]# pacman -Qs texlive
[root@fab aragorn]#

$ pacman -Qs emacs

 [root@fab aragorn]# pacman -Qs emacs
local/emacs 26.1-2
    The extensible, customizable, self-documenting real-time display editor
local/emacs-python-mode 6.2.3-1
    Python mode for Emacs
[root@fab aragorn]#

you mentioned that commands run in terminal worked fine, but you
  invoked them by full path;

 
To be able to test with the
texlive context binary and context standalone context binary
.


The next in the next message after restarting my PC ...

Fabrice
 

Le mer. 29 août 2018 à 04:58, Vladimir Lomov <lomov.vl@yandex.ru> a écrit :
Hello,
** Fabrice Couvreur [2018-08-28 11:18:58 +0200]:

> Hi Vladimir,

> I do not use Arch Linux repositories to install  texlive 2018 packages

Some texlive-* packages could be installed as dependencies of other
packages. You may check if your system has any texlive package:

  $ pacman -Qs texlive

> but I installed texlive 2018 "scheme-full" with tlmgr -gui  in
> /home/aragorn /texlive/2018.  I then make regular updates in the same
> way. No texlive traces in the \usr\share\ directory or elsewhere.

I prefer to rely on package manager.

> Standalone Context is also installed in my home directory. However,
> Emacs is installed from the Arch Linux repositories and is located in
> /usr/share/emacs.

  $ pacman -Qs emacs

> So I have to add the path of texlive 2018 ?
> Maybe you do not need to add the Context Standalone path ?
> My ~/.profile file would be this :
>
> source /home/aragorn/context/tex/setuptex
> export PATH = $ PATH: /home/aragorn/texlive/2018/bin/x86_64-linux
> export PATH = $ PATH: /home/aragorn /bin

This part is a bit strange:
- in message
  https://mailman.ntg.nl/pipermail/ntg-context/2018/092418.html
  you mentioned that commands run in terminal worked fine, but you
  invoked them by full path;

- in the same message you set PATH in emacs as

    (setenv "PATH" "/home/aragorn/context/tex/texmf-linux-64/bin/:$PATH" t)

  (I have to admit that I didn't know it is possible to use '$PATH' in
  setenv), so it prepends path to context binary to PATH list. The above
  lines do opposite: they append path to context binary to the end of
  PATH list.

  The first line, 'source ...', helps here because 'setuptex' in turns
  prepend path to context binary to PATH.

When you invoke 'context' in terminal (I assume it is bash shell) the
shell searches program in current directory (depends on configuration)
and then in PATH, the first wins. So to use context from ConTeXt
standalone you may simply do

  $ export PATH=$HOME/context/tex/texmf-linux-64/bin:$PATH

either in terminal or in ~/.profile. You may always check if this is
true by runnig

  $ command -v context

(for bash shell) or

  $ which context

Returning to your problem. I looked closely again in messages with
output from context and I don't understand what may cause the error.
Seems that Emacs uses correct context (according to loading files).
Could you show in full your ~/.emacs file? Do you use AUCTeX or bare
Emacs?

> Regards,
> Fabrice
>

[...]

---
WBR, Vladimir Lomov


--
Uncontrolled power will turn even saints into savages.  And we can all
be counted on to live down to our lowest impulses.
                -- Parmen, "Plato's Stepchildren", stardate 5784.3
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