[bug#65229] [PATCH 0/2] Add '-q' for 'pull' and 'time-machine'; support loading from pipes

[bug#65229] [PATCH 0/2] Add '-q' for 'pull' and 'time-machine'; support loading from pipes

[Ludovic Courtès]

Hello!

These patches address two related issues:

  • The first one adds ‘-q’ to ‘pull’ and ‘time-machine’ to
    instruct them to ignore the user/system ‘channels.scm’ file.
    That way, a command like the following is guaranteed to have
    the same semantics regardless of available config files:

      guix time-machine -q --commit=v1.2.0 -- build hello

    This issue had been raised in
    <https://issues.guix.gnu.org/63726>.

  • The second one lets users do things (in Bash) like:

      guix time-machine -C <(echo %default-channels) -- …

Feedback welcome!

Ludo’.

Ludovic Courtès (2):
  pull, time-machine: Add '-q' to ignore channel files.
  ui: 'load*' accepts /dev/fd/N files pointing to a pipe.

 doc/guix.texi                 | 30 ++++++++++++++++++++++--------
 guix/scripts/pull.scm         | 14 ++++++++++++--
 guix/scripts/time-machine.scm |  7 ++++++-
 guix/ui.scm                   | 16 +++++++++++++++-
 tests/guix-build.sh           |  9 ++++++++-
 5 files changed, 63 insertions(+), 13 deletions(-)


base-commit: 56fddefc6de3b0c1f2ccb9559d86ba08d2e429b9
-- 
2.41.0

[bug#65229] [PATCH 1/2] pull, time-machine: Add '-q' to ignore channel files.

[Ludovic Courtès]

From: Ludovic Courtès <ludovic.courtes@inria.fr>

This also fixes <https://issues.guix.gnu.org/63726>.

* guix/scripts/pull.scm (show-help, %options): Add '-q'.
(channel-list): Honor it.
* guix/scripts/time-machine.scm (show-help, %options): Add '-q'.
* doc/guix.texi (Invoking guix pull, Invoking guix time-machine):
Document it.

Reported-by: Simon Tournier <zimon.toutoune@gmail.com>
---
 doc/guix.texi                 | 30 ++++++++++++++++++++++--------
 guix/scripts/pull.scm         | 14 ++++++++++++--
 guix/scripts/time-machine.scm |  7 ++++++-
 3 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 409ca2ad62..ec36159de1 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4801,9 +4801,11 @@ Invoking guix pull
 @item
 the @option{--channels} option;
 @item
-the user's @file{~/.config/guix/channels.scm} file;
+the user's @file{~/.config/guix/channels.scm} file, unless @option{-q}
+is passed;
 @item
-the system-wide @file{/etc/guix/channels.scm} file;
+the system-wide @file{/etc/guix/channels.scm} file, unless @option{-q}
+is passed;
 @item
 the built-in default channels specified in the @code{%default-channels}
 variable.
@@ -4905,6 +4907,10 @@ Invoking guix pull
 evaluates to a list of channel objects.  @xref{Channels}, for more
 information.
 
+@item -q
+Inhibit loading of the user and system channel files,
+@file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}.
+
 @cindex channel news
 @item --news
 @itemx -N
@@ -5092,18 +5098,26 @@ Invoking guix time-machine
 Read the list of channels from @var{file}.  @var{file} must contain
 Scheme code that evaluates to a list of channel objects.
 @xref{Channels} for more information.
+
+@item -q
+Inhibit loading of the user and system channel files,
+@file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}.
 @end table
 
-As for @command{guix pull}, the absence of any options means that the
-latest commit on the master branch will be used.  The command
+As for @command{guix pull}, in the absence of any options,
+@command{time-machine} fetches the latest commits of the channels
+specified in @file{~/.config/guix/channels.scm},
+@file{/etc/guix/channels.scm}, or the default channels; the @option{-q}
+option lets you ignore these configuration files.  The command:
 
 @example
-guix time-machine -- build hello
+guix time-machine -q -- build hello
 @end example
 
-will thus build the package @code{hello} as defined in the master branch,
-which is in general a newer revision of Guix than you have installed.
-Time travel works in both directions!
+will thus build the package @code{hello} as defined in the main branch
+of Guix, without any additional channel, which is in general a newer
+revision of Guix than you have installed.  Time travel works in both
+directions!
 
 Note that @command{guix time-machine} can trigger builds of channels and
 their dependencies, and these are controlled by the standard build
diff --git a/guix/scripts/pull.scm b/guix/scripts/pull.scm
index ecd264d3fa..f0d4ff36e6 100644
--- a/guix/scripts/pull.scm
+++ b/guix/scripts/pull.scm
@@ -84,6 +84,8 @@ (define (show-help)
 Download and deploy the latest version of Guix.\n"))
   (display (G_ "
   -C, --channels=FILE    deploy the channels defined in FILE"))
+  (display (G_ "
+  -q                     inhibit loading of user and system 'channels.scm'"))
   (display (G_ "
       --url=URL          download \"guix\" channel from the Git repository at URL"))
   (display (G_ "
@@ -133,6 +135,9 @@ (define %options
   (cons* (option '(#\C "channels") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'channel-file arg result)))
+         (option '(#\q) #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'ignore-channel-files? #t result)))
          (option '(#\l "list-generations") #f #t
                  (lambda (opt name arg result)
                    (cons `(query list-generations ,arg)
@@ -735,6 +740,9 @@ (define (channel-list opts)
   (define file
     (assoc-ref opts 'channel-file))
 
+  (define ignore-channel-files?
+    (assoc-ref opts 'ignore-channel-files?))
+
   (define default-file
     (string-append (config-directory) "/channels.scm"))
 
@@ -750,9 +758,11 @@ (define (channel-list opts)
   (define channels
     (cond (file
            (load-channels file))
-          ((file-exists? default-file)
+          ((and (not ignore-channel-files?)
+                (file-exists? default-file))
            (load-channels default-file))
-          ((file-exists? global-file)
+          ((and (not ignore-channel-files?)
+                (file-exists? global-file))
            (load-channels global-file))
           (else
            %default-channels)))
diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm
index d7c71ef705..8afea6b35d 100644
--- a/guix/scripts/time-machine.scm
+++ b/guix/scripts/time-machine.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2019 Konrad Hinsen <konrad.hinsen@fastmail.net>
-;;; Copyright © 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019, 2020, 2021, 2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -51,6 +51,8 @@ (define (show-help)
 Execute COMMAND ARGS... in an older version of Guix.\n"))
   (display (G_ "
   -C, --channels=FILE    deploy the channels defined in FILE"))
+  (display (G_ "
+  -q                     inhibit loading of user and system 'channels.scm'"))
   (display (G_ "
       --url=URL          use the Git repository at URL"))
   (display (G_ "
@@ -75,6 +77,9 @@ (define %options
   (cons* (option '(#\C "channels") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'channel-file arg result)))
+         (option '(#\q) #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'ignore-channel-files? #t result)))
          (option '("url") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'repository-url arg
-- 
2.41.0

[bug#65229] [PATCH 2/2] ui: 'load*' accepts /dev/fd/N files pointing to a pipe.

[Ludovic Courtès]

From: Ludovic Courtès <ludovic.courtes@inria.fr>

This allows users to write Bash commands like:

  guix time-machine -C <(echo %default-channels) -- ...

or:

  guix build -m <(echo '(specifications->manifest (list "guile"))')

Previously, on GNU/Linux, they would fail with:

  error: failed to load '/dev/fd/63': No such file or directory

* guix/ui.scm (try-canonicalize-path): New procedure.
(load*): Use it.
* tests/guix-build.sh: Test 'guix build -m' with a /dev/fd/N file.
---
 guix/ui.scm         | 16 +++++++++++++++-
 tests/guix-build.sh |  9 ++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/guix/ui.scm b/guix/ui.scm
index 47a118364a..6f2d4fe245 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -200,6 +200,20 @@ (define-syntax-rule (without-compiler-optimizations exp)
   (parameterize (((@ (system base compile) default-optimization-level) 1))
     exp))
 
+(define (try-canonicalize-path file)
+  "Like 'canonicalize-path', but return FILE as-is if 'canonicalize-path'
+throws.
+
+This is necessary for corner cases where 'canonicalize-path' fails.  One
+example is on Linux when a /dev/fd/N file denotes a pipe, represented as a
+symlink to a non-existent file like 'pipe:[1234]', as in this example:
+
+  sh -c 'stat $(readlink -f /dev/fd/1)' | cat"
+  (catch 'system-error
+    (lambda ()
+      (canonicalize-path file))
+    (const file)))
+
 (define* (load* file user-module
                 #:key (on-error 'nothing-special))
   "Load the user provided Scheme source code FILE."
@@ -230,7 +244,7 @@ (define* (load* file user-module
                ;; 'primitive-load', so that FILE is compiled, which then allows
                ;; us to provide better error reporting with source line numbers.
                (without-compiler-optimizations
-                (load (canonicalize-path file))))
+                (load (try-canonicalize-path file))))
              (const #f))))))
     (lambda _
       ;; XXX: Errors are reported from the pre-unwind handler below, but
diff --git a/tests/guix-build.sh b/tests/guix-build.sh
index 317c58ac42..4eab0e38b6 100644
--- a/tests/guix-build.sh
+++ b/tests/guix-build.sh
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2012-2014, 2016-2022 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2012-2014, 2016-2023 Ludovic Courtès <ludo@gnu.org>
 # Copyright © 2020 Marius Bakke <mbakke@fastmail.com>
 # Copyright © 2021 Chris Marusich <cmmarusich@gmail.com>
 #
@@ -397,6 +397,13 @@ guix build -d -m "$module_dir/manifest.scm" \
 
 rm "$module_dir"/*.scm
 
+if [ -n "$BASH_VERSION" ]
+then
+    # Check whether we can load from a /dev/fd/N denoting a pipe, using this
+    # handy Bash-specific construct.
+    guix build -m <(echo '(specifications->manifest (list "guile"))') -n
+fi
+
 # Using 'GUIX_BUILD_OPTIONS'.
 GUIX_BUILD_OPTIONS="--dry-run --no-grafts"
 export GUIX_BUILD_OPTIONS
-- 
2.41.0

[bug#65229] [PATCH 1/2] pull, time-machine: Add '-q' to ignore channel files.

[Simon Tournier]

Hi Ludo,

Cool addition!

On Fri, 11 Aug 2023 at 17:34, Ludovic Courtès <ludo@gnu.org> wrote:

> -As for @command{guix pull}, the absence of any options means that the
> -latest commit on the master branch will be used.  The command
> +As for @command{guix pull}, in the absence of any options,
> +@command{time-machine} fetches the latest commits of the channels
> +specified in @file{~/.config/guix/channels.scm},
> +@file{/etc/guix/channels.scm}, or the default channels; the @option{-q}
> +option lets you ignore these configuration files.  The command:
>  
>  @example
> -guix time-machine -- build hello
> +guix time-machine -q -- build hello
>  @end example
>  
> -will thus build the package @code{hello} as defined in the master branch,
> -which is in general a newer revision of Guix than you have installed.
> -Time travel works in both directions!
> +will thus build the package @code{hello} as defined in the main branch

Why not the master branch?  Is the branch renamed from ’master’ to
’main’?  If not, I would keep the explicit master branch in order to
avoid confusion.

> +of Guix, without any additional channel, which is in general a newer
> +revision of Guix than you have installed.  Time travel works in both
> +directions!

Well, I would keep the previous example because the behaviour appears to
me more prone-error.  I mean, by default, there is no channels.scm file
under ~/.config/guix/ or /etc/guix, therefore an explanation of the
behaviour without any option at all appears to me worth.  Moreover,
since there is no channels.scm file by default, i.e., the default is
%default-channels, it appears to me weird to explain the specific
behaviour (without any option and reaching new revision) using an option
turning off the channels.scm file.



> diff --git a/guix/scripts/pull.scm b/guix/scripts/pull.scm

> +  (display (G_ "
> +  -q                     inhibit loading of user and system 'channels.scm'"))

[...]

> diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm

> +  (display (G_ "
> +  -q                     inhibit loading of user and system 'channels.scm'"))

No long option?  As --no-channel-files or --ignore-channel-files ?


Cheers,
simon

[bug#65229] [PATCH 2/2] ui: 'load*' accepts /dev/fd/N files pointing to a pipe.

[Simon Tournier]

Hi Ludo,

Cool!

On Fri, 11 Aug 2023 at 17:34, Ludovic Courtès <ludo@gnu.org> wrote:

> This allows users to write Bash commands like:
>
>   guix time-machine -C <(echo %default-channels) -- ...
>
> or:
>
>   guix build -m <(echo '(specifications->manifest (list "guile"))')

I propose to document this.  WDYT about this?

--8<---------------cut here---------------start------------->8---
1 file changed, 6 insertions(+)
doc/guix.texi | 6 ++++++

modified   doc/guix.texi
@@ -5103,6 +5103,12 @@ Invoking guix time-machine
 @item -q
 Inhibit loading of the user and system channel files,
 @file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}.
+
+This option is equivalent to the command run on Bash shell:
+
+@example
+guix time-machine -C <(echo %default-channels) -- build hello
+@end example
 @end table
 
 As for @command{guix pull}, in the absence of any options,
--8<---------------cut here---------------end--------------->8---


Cheers,
simon

[bug#65229] [PATCH 1/2] pull, time-machine: Add '-q' to ignore channel files.

[Simon Tournier]

Re,

On Wed, 16 Aug 2023 at 14:59, Simon Tournier <zimon.toutoune@gmail.com> wrote:

> Well, I would keep the previous example because the behaviour appears to
> me more prone-error.  I mean, by default, there is no channels.scm file
> under ~/.config/guix/ or /etc/guix, therefore an explanation of the
> behaviour without any option at all appears to me worth.  Moreover,
> since there is no channels.scm file by default, i.e., the default is
> %default-channels, it appears to me weird to explain the specific
> behaviour (without any option and reaching new revision) using an option
> turning off the channels.scm file.

Somehow, I would keep something like [1]:

--8<---------------cut here---------------start------------->8---
Similarly as @command{guix pull}, the absence of any options means that
either the user's @file{~/.config/guix/channels.scm} file, or either the
system-wide @file{/etc/guix/channels.scm} file, or either the built-in
default channels specified in the @code{%default-channels} will be
honored, in that order.  The command

 @example
 guix time-machine -- build hello
 @end example

will thus build the package @code{hello} as defined by the previous
@dfn{channels} file (@pxref{Channels}).  In general, it builds a newer
revision of Guix than you have installed.  Time travel works in both
directions!
--8<---------------cut here---------------end--------------->8---

1: https://yhetil.org/guix/87r0qyrlm0.fsf@gmail.com


Cheers,
simon

[bug#65229] [PATCH 1/2] pull, time-machine: Add '-q' to ignore channel files.

[Ludovic Courtès]

Hi,

Simon Tournier <zimon.toutoune@gmail.com> skribis:

> On Fri, 11 Aug 2023 at 17:34, Ludovic Courtès <ludo@gnu.org> wrote:

[...]

>> -will thus build the package @code{hello} as defined in the master branch,
>> -which is in general a newer revision of Guix than you have installed.
>> -Time travel works in both directions!
>> +will thus build the package @code{hello} as defined in the main branch
>
> Why not the master branch?  Is the branch renamed from ’master’ to
> ’main’?  If not, I would keep the explicit master branch in order to
> avoid confusion.

The “main branch” is the branch currently called ‘master’ (I think we
should rename it to ‘main’ eventually, but I’d have written @code{main}
if I wanted to imply it’s called that way).

>> +of Guix, without any additional channel, which is in general a newer
>> +revision of Guix than you have installed.  Time travel works in both
>> +directions!
>
> Well, I would keep the previous example because the behaviour appears to
> me more prone-error.  I mean, by default, there is no channels.scm file
> under ~/.config/guix/ or /etc/guix, therefore an explanation of the
> behaviour without any option at all appears to me worth.  Moreover,
> since there is no channels.scm file by default, i.e., the default is
> %default-channels, it appears to me weird to explain the specific
> behaviour (without any option and reaching new revision) using an option
> turning off the channels.scm file.

I thought that we cannot easily describe what ‘guix time-machine --
build hello’ does, precisely because it depends on whether
‘channels.scm’ files are present and on what they do.  Conversely,
explaining what happens with ‘-q’ is trivial because it doesn’t depend
on external state.

Anyway, I’ll try and reword that.

>> diff --git a/guix/scripts/pull.scm b/guix/scripts/pull.scm
>
>> +  (display (G_ "
>> +  -q                     inhibit loading of user and system 'channels.scm'"))
>
> [...]
>
>> diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm
>
>> +  (display (G_ "
>> +  -q                     inhibit loading of user and system 'channels.scm'"))
>
> No long option?  As --no-channel-files or --ignore-channel-files ?

Yeah, I thought we’d follow ‘guix repl’ and ‘guile’, which have no long
option, but maybe we should add ‘--no-channel-files’.

Thanks you; I’ll send a new version.

Ludo’.

[bug#65229] [PATCH 1/2] pull, time-machine: Add '-q' to ignore channel files.

[Simon Tournier]

Hi Ludo,

On Thu, 17 Aug 2023 at 10:57, Ludovic Courtès <ludo@gnu.org> wrote:

> >> -will thus build the package @code{hello} as defined in the master branch,
> >> -which is in general a newer revision of Guix than you have installed.
> >> -Time travel works in both directions!
> >> +will thus build the package @code{hello} as defined in the main branch
> >
> > Why not the master branch?  Is the branch renamed from ’master’ to
> > ’main’?  If not, I would keep the explicit master branch in order to
> > avoid confusion.
>
> The “main branch” is the branch currently called ‘master’ (I think we
> should rename it to ‘main’ eventually, but I’d have written @code{main}
> if I wanted to imply it’s called that way).

I think the term "main branch" is confusing because many forges as
Gitlab propose by default to rename from @code{master}  to
@code{main}.  Well, if instead of @code{main}, these forges were
proposing @code{trunk} or @code{primary} or whatever else, it would be
fine.

Therefore, I propose the wording:

    defined in the main branch of Guix (currently called @code{master}), without
    any additional channel, [...]

Cheers,
simon

[bug#65229] [PATCH v2 1/2] ui: 'load*' accepts /dev/fd/N files pointing to a pipe.

[Ludovic Courtès]

From: Ludovic Courtès <ludovic.courtes@inria.fr>

This allows users to write Bash commands like:

  guix time-machine -C <(echo %default-channels) -- ...

or:

  guix build -m <(echo '(specifications->manifest (list "guile"))')

Previously, on GNU/Linux, they would fail with:

  error: failed to load '/dev/fd/63': No such file or directory

* guix/ui.scm (try-canonicalize-path): New procedure.
(load*): Use it.
* tests/guix-build.sh: Test 'guix build -m' with a /dev/fd/N file.
---
 guix/ui.scm         | 16 +++++++++++++++-
 tests/guix-build.sh |  9 ++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/guix/ui.scm b/guix/ui.scm
index 47a118364a..6f2d4fe245 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -200,6 +200,20 @@ (define-syntax-rule (without-compiler-optimizations exp)
   (parameterize (((@ (system base compile) default-optimization-level) 1))
     exp))
 
+(define (try-canonicalize-path file)
+  "Like 'canonicalize-path', but return FILE as-is if 'canonicalize-path'
+throws.
+
+This is necessary for corner cases where 'canonicalize-path' fails.  One
+example is on Linux when a /dev/fd/N file denotes a pipe, represented as a
+symlink to a non-existent file like 'pipe:[1234]', as in this example:
+
+  sh -c 'stat $(readlink -f /dev/fd/1)' | cat"
+  (catch 'system-error
+    (lambda ()
+      (canonicalize-path file))
+    (const file)))
+
 (define* (load* file user-module
                 #:key (on-error 'nothing-special))
   "Load the user provided Scheme source code FILE."
@@ -230,7 +244,7 @@ (define* (load* file user-module
                ;; 'primitive-load', so that FILE is compiled, which then allows
                ;; us to provide better error reporting with source line numbers.
                (without-compiler-optimizations
-                (load (canonicalize-path file))))
+                (load (try-canonicalize-path file))))
              (const #f))))))
     (lambda _
       ;; XXX: Errors are reported from the pre-unwind handler below, but
diff --git a/tests/guix-build.sh b/tests/guix-build.sh
index 317c58ac42..4eab0e38b6 100644
--- a/tests/guix-build.sh
+++ b/tests/guix-build.sh
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2012-2014, 2016-2022 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2012-2014, 2016-2023 Ludovic Courtès <ludo@gnu.org>
 # Copyright © 2020 Marius Bakke <mbakke@fastmail.com>
 # Copyright © 2021 Chris Marusich <cmmarusich@gmail.com>
 #
@@ -397,6 +397,13 @@ guix build -d -m "$module_dir/manifest.scm" \
 
 rm "$module_dir"/*.scm
 
+if [ -n "$BASH_VERSION" ]
+then
+    # Check whether we can load from a /dev/fd/N denoting a pipe, using this
+    # handy Bash-specific construct.
+    guix build -m <(echo '(specifications->manifest (list "guile"))') -n
+fi
+
 # Using 'GUIX_BUILD_OPTIONS'.
 GUIX_BUILD_OPTIONS="--dry-run --no-grafts"
 export GUIX_BUILD_OPTIONS

base-commit: 1bd44b425b79e9da160b33a9b19d01973b44772e
-- 
2.41.0

[bug#65229] [PATCH v2 2/2] pull, time-machine: Add '-q' to ignore channel files.

[Ludovic Courtès]

From: Ludovic Courtès <ludovic.courtes@inria.fr>

This also fixes <https://issues.guix.gnu.org/63726>.

* guix/scripts/pull.scm (show-help, %options): Add '-q'.
(channel-list): Honor it.
* guix/scripts/time-machine.scm (show-help, %options): Add '-q'.
* doc/guix.texi (Invoking guix pull, Invoking guix time-machine):
Document it.

Reported-by: Simon Tournier <zimon.toutoune@gmail.com>
---
 doc/guix.texi                 | 47 +++++++++++++++++++++++++++--------
 guix/scripts/pull.scm         | 15 +++++++++--
 guix/scripts/time-machine.scm |  8 +++++-
 3 files changed, 57 insertions(+), 13 deletions(-)

Changes since v1:

  • Add ‘--no-channel-files’.

  • Join the two ‘time-machine’ examples, the one without ‘-q’ and
    the one with ‘-q’ (I realized there was already one example
    without ‘-q’ so I figured it was easier to clarify ‘channels.scm’
    handling upfront).

  • Document the <(echo %default-channels) trick.

Let me know what you think!

Ludo’.

diff --git a/doc/guix.texi b/doc/guix.texi
index 633d62bd98..2d54b92fa5 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4802,9 +4802,11 @@ Invoking guix pull
 @item
 the @option{--channels} option;
 @item
-the user's @file{~/.config/guix/channels.scm} file;
+the user's @file{~/.config/guix/channels.scm} file, unless @option{-q}
+is passed;
 @item
-the system-wide @file{/etc/guix/channels.scm} file;
+the system-wide @file{/etc/guix/channels.scm} file, unless @option{-q}
+is passed;
 @item
 the built-in default channels specified in the @code{%default-channels}
 variable.
@@ -4906,6 +4908,11 @@ Invoking guix pull
 evaluates to a list of channel objects.  @xref{Channels}, for more
 information.
 
+@item --no-channel-files
+@itemx -q
+Inhibit loading of the user and system channel files,
+@file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}.
+
 @cindex channel news
 @item --news
 @itemx -N
@@ -5051,7 +5058,9 @@ Invoking guix time-machine
   environment -C --ad-hoc guile -- guile
 @end example
 
-The command above fetches Guix@tie{}1.2.0 and runs its @command{guix
+The command above fetches Guix@tie{}1.2.0 (and possibly other channels
+specified by your @file{channels.scm} configuration files---see
+below) and runs its @command{guix
 environment} command to spawn an environment in a container running
 @command{guile} (@command{guix environment} has since been subsumed by
 @command{guix shell}; @pxref{Invoking guix shell}).  It's like driving a
@@ -5061,6 +5070,21 @@ Invoking guix time-machine
 large number of packages; the result is cached though and subsequent
 commands targeting the same commit are almost instantaneous.
 
+As for @command{guix pull}, in the absence of any options,
+@command{time-machine} fetches the latest commits of the channels
+specified in @file{~/.config/guix/channels.scm},
+@file{/etc/guix/channels.scm}, or the default channels; the @option{-q}
+option lets you ignore these configuration files.  The command:
+
+@example
+guix time-machine -q -- build hello
+@end example
+
+will thus build the package @code{hello} as defined in the main branch
+of Guix, without any additional channel, which is in general a newer
+revision of Guix than you have installed.  Time travel works in both
+directions!
+
 @quotation Note
 The history of Guix is immutable and @command{guix time-machine}
 provides the exact same software as they are in a specific Guix
@@ -5093,18 +5117,21 @@ Invoking guix time-machine
 Read the list of channels from @var{file}.  @var{file} must contain
 Scheme code that evaluates to a list of channel objects.
 @xref{Channels} for more information.
-@end table
 
-As for @command{guix pull}, the absence of any options means that the
-latest commit on the master branch will be used.  The command
+@item --no-channel-files
+@itemx -q
+Inhibit loading of the user and system channel files,
+@file{~/.config/guix/channels.scm} and @file{/etc/guix/channels.scm}.
+
+Thus, @command{guix time-machine -q} is equivalent to the following Bash
+command, using the ``process substitution'' syntax (@pxref{Process
+Substitution,,, bash, The GNU Bash Reference Manual}):
 
 @example
-guix time-machine -- build hello
+guix time-machine -C <(echo %default-channels) @dots{}
 @end example
 
-will thus build the package @code{hello} as defined in the master branch,
-which is in general a newer revision of Guix than you have installed.
-Time travel works in both directions!
+@end table
 
 Note that @command{guix time-machine} can trigger builds of channels and
 their dependencies, and these are controlled by the standard build
diff --git a/guix/scripts/pull.scm b/guix/scripts/pull.scm
index ecd264d3fa..3a8dd6ea01 100644
--- a/guix/scripts/pull.scm
+++ b/guix/scripts/pull.scm
@@ -84,6 +84,9 @@ (define (show-help)
 Download and deploy the latest version of Guix.\n"))
   (display (G_ "
   -C, --channels=FILE    deploy the channels defined in FILE"))
+  (display (G_ "
+  -q, --no-channel-files
+                         inhibit loading of user and system 'channels.scm'"))
   (display (G_ "
       --url=URL          download \"guix\" channel from the Git repository at URL"))
   (display (G_ "
@@ -133,6 +136,9 @@ (define %options
   (cons* (option '(#\C "channels") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'channel-file arg result)))
+         (option '(#\q "no-channel-files") #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'ignore-channel-files? #t result)))
          (option '(#\l "list-generations") #f #t
                  (lambda (opt name arg result)
                    (cons `(query list-generations ,arg)
@@ -735,6 +741,9 @@ (define (channel-list opts)
   (define file
     (assoc-ref opts 'channel-file))
 
+  (define ignore-channel-files?
+    (assoc-ref opts 'ignore-channel-files?))
+
   (define default-file
     (string-append (config-directory) "/channels.scm"))
 
@@ -750,9 +759,11 @@ (define (channel-list opts)
   (define channels
     (cond (file
            (load-channels file))
-          ((file-exists? default-file)
+          ((and (not ignore-channel-files?)
+                (file-exists? default-file))
            (load-channels default-file))
-          ((file-exists? global-file)
+          ((and (not ignore-channel-files?)
+                (file-exists? global-file))
            (load-channels global-file))
           (else
            %default-channels)))
diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm
index d7c71ef705..fa12e6f170 100644
--- a/guix/scripts/time-machine.scm
+++ b/guix/scripts/time-machine.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2019 Konrad Hinsen <konrad.hinsen@fastmail.net>
-;;; Copyright © 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019, 2020, 2021, 2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -51,6 +51,9 @@ (define (show-help)
 Execute COMMAND ARGS... in an older version of Guix.\n"))
   (display (G_ "
   -C, --channels=FILE    deploy the channels defined in FILE"))
+  (display (G_ "
+  -q, --no-channel-files
+                         inhibit loading of user and system 'channels.scm'"))
   (display (G_ "
       --url=URL          use the Git repository at URL"))
   (display (G_ "
@@ -75,6 +78,9 @@ (define %options
   (cons* (option '(#\C "channels") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'channel-file arg result)))
+         (option '(#\q "no-channel-files") #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'ignore-channel-files? #t result)))
          (option '("url") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'repository-url arg
-- 
2.41.0

[bug#65229] [PATCH v2 2/2] pull, time-machine: Add '-q' to ignore channel files.

[Simon Tournier]

Hi,

On Thu, 17 Aug 2023 at 12:17, Ludovic Courtès <ludo@gnu.org> wrote:

>   • Document the <(echo %default-channels) trick.

LGTM!

Well, it appears to me weird to document with this patch this track
and then introduce the implementation in the next commit.  Anyway,
it's nitpicking. :-)
However, as I mentioned, I still find confusing the wording "main
branch" and I think "main branch of Guix (currently named
@code{master))" fixes the confusion.

Cheers,
simon

bug#65229: [PATCH 0/2] Add '-q' for 'pull' and 'time-machine'; support loading from pipes

[Ludovic Courtès]

Simon Tournier <zimon.toutoune@gmail.com> skribis:

> On Thu, 17 Aug 2023 at 12:17, Ludovic Courtès <ludo@gnu.org> wrote:
>
>>   • Document the <(echo %default-channels) trick.
>
> LGTM!

Pushed as 9c8098424b5be3abf21144c74162ec39c0c2e799, thanks!

Ludo’.