guix system: Add '--derivation'.

* guix/scripts/system.scm (perform-action): Add #:derivations-only?
  parameter and honor it.
  (show-help, %options): Add '--derivation'.
  (guix-system): Pass #:derivations-only? to 'perform-action'.
* tests/guix-system.sh: Test it.
* doc/guix.texi (Invoking guix system): Document it.

scripts: environment: Use system* instead of system.

This allows for direct program invokation without needing a shell to act
as a command interpreter.

* guix/scripts/environment.scm (%default-shell): New variable.
  (show-help): Adjust description.  Remove '--exec' reference.
  (%default-options): Use '%default-shell'.
  (%options): Adjust '--exec' to run command via the default shell.
  (parse-args): New procedure.
  (guix-environment): Use 'parse-args'.  Use 'system*' instead of
  'system'.
* tests/guix-environment.sh: Add test for '--' command invokation.
* doc/guix.texi ("Invoking guix environment"): Use new syntax.  Remove
  '--exec' documentation.

lint: Export 'run-checkers'.

* guix/scripts/lint.scm (run-checkers): Export.  Make 'checkers'
  argument optional.

Merge branch 'master' into core-updates

publish: Fix file descriptor leak.

A client closing the connection while reading from a /nar URL would
leave an open file descriptor in the server.  This patch fixes it.

* guix/scripts/publish.scm (swallow-EPIPE): New macro.
  (http-write): Use it around 'write-file' call.

guix gc: Add '--list-failures' and '--clear-failures'.

Suggested by Mark H Weaver <mhw@netris.org>.

* guix/scripts/gc.scm (show-help, %options): Add --list-failures and
  --clear-failures.
  (guix-gc): Honor them.
* doc/guix.texi (Invoking guix gc): Document them.
  (Invoking guix-daemon): Mention them.

lint: Fix 'check-texinfo-markup'.

Fixes a regression introduced in 5d8d8f3.

* guix/scripts/lint.scm (check-description-style): When no exception is
  thrown in 'check-texinfo-markup', return the rendered description.

lint: Improve 'check-texinfo-markup'.

* guix/scripts/lint.scm (check-description-style): Set 'field' parameter
  when emitting a warning in 'check-texinfo-markup'.  Catch any error
  that may occur in during the 'texi->plain-text' conversion.  This is a
  followup to commit 2748ee3.

offload: Use gzip instead of xz for compression on the master.

* guix/scripts/offload.scm (send-files): Use gzip --fast instead of xz.

lint: Accept '`' character.

* guix/scripts/lint.scm (properly-starts-sentence?): Match Texinfo
  highlighting commands as a sentence start.

lint: Check non-translated package descriptions.

* guix/ui.scm (texi->plain-text): Export.
* guix/scripts/lint.scm (check-description-style): Use it instead of
  'package-description-string'.

Merge branch 'master' into core-updates

scripts: Add 'build-package'.

* guix/scripts/system.scm (maybe-build): Move to ...
* guix/scripts.scm: ...here.
  (build-package): New procedure.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

lint: Report lonely parentheses.

* guix/scripts/lint.scm (%hanging-paren-rx): New variable.
  (report-lone-parentheses): New procedure.
  (%formatting-reporters): Use it.
* tests/lint.scm ("formatting: lonely parentheses"): New test.

ui: Add 'show-derivation-outputs'.

* guix/scripts/build.scm (guix-build): Extract code from here and move to...
* guix/ui.scm (show-derivation-outputs): ... here.  New procedure.

Add (guix scripts).

* guix/ui.scm: Add missing copyright lines.
  (args-fold*, environment-build-options, %default-argument-handler,
  parse-command-line): Move to ...
* guix/scripts.scm: ...here.  New file.
* guix/scripts/archive.scm: Use it.
* guix/scripts/build.scm: Likewise.
* guix/scripts/download.scm: Likewise.
* guix/scripts/edit.scm: Likewise.
* guix/scripts/environment.scm: Likewise.
* guix/scripts/gc.scm: Likewise.
* guix/scripts/graph.scm: Likewise.
* guix/scripts/hash.scm: Likewise.
* guix/scripts/import/cpan.scm: Likewise.
* guix/scripts/import/cran.scm: Likewise.
* guix/scripts/import/elpa.scm: Likewise.
* guix/scripts/import/gem.scm: Likewise.
* guix/scripts/import/gnu.scm: Likewise.
* guix/scripts/import/hackage.scm: Likewise.
* guix/scripts/import/nix.scm: Likewise.
* guix/scripts/import/pypi.scm: Likewise.
* guix/scripts/lint.scm: Likewise.
* guix/scripts/package.scm: Likewise.
* guix/scripts/publish.scm: Likewise.
* guix/scripts/pull.scm: Likewise.
* guix/scripts/refresh.scm: Likewise.
* guix/scripts/size.scm: Likewise.
* guix/scripts/system.scm: Likewise.
* tests/ui.scm (with-environment-variable, "parse-command-line",
  "parse-command-line and --no options"): Move to ...
* tests/scripts.scm: ...here.  New file.
* Makefile.am (MODULES): Add guix/scripts.scm.
  (SCM_TESTS): Add tests/scripts.scm.
* po/guix/POTFILES.in: Add guix/scripts.scm.

substitute: Improve readability of download progress report.

* guix/build/download.scm
  (string-pad-middle, store-url-abbreviation, store-path-abbreviation):
  New procedures.
  (progress-proc): Add #:abbreviation parameter and use it.  Generate a
  better indeterminate progress string.
* guix/scripts/substitute.scm (assert-valid-narinfo): Add newlines to output.
  (process-substitution): Use byte-count->string and store-path-abbreviation.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

lint: Add 'check-texinfo-markup' checker.

* guix/script/lint.scm (check-description-style): Check for invalid
  Texinfo markup.
* tests/lint.scm: Test it.

guix: lint: Check for meaningful origin file names.

* guix/scripts/lint.scm (check-source-file-name): New procedure.
  (%checkers): Add 'source-file-name' checker.
* tests/lint.scm ("source-file-name", "source-file-name: v prefix")
  ("source-file-name: valid", "source-file-name: bad checkout")
  ("source-file-name: good checkout"): New tests.
* doc/guix.texi (Invoking guix lint): Mention file name check.

guix: packages: Add origin-actual-file-name.

* guix/scripts/graph.scm (uri->file-name, node-full-name): Move origin file
  name logic to...
* guix/packages.scm (origin-actual-file-name): ...here.
* tests/packages.scm ("origin-actual-file-name")
  ("origin-actual-file-name, file-name"): New tests.