Auto merge of #12295 - jimberlage:12158/shell-linting, r=aneeshusa

Add linting for shell scripts

<!-- Please describe your changes on the following line: -->

This changes tidy to check shell scripts for the proper shebang and
options.  It does not check that variables are formatted correctly.  It
also adds a check for the MPL 2.0 license in shell scripts.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #12158 (github issue number if applicable).

<!-- Either: -->
- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

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---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/12295)
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etc/ci/check_no_unwrap.sh

@@ -1,12 +1,17 @@
 #!/usr/bin/env bash
-#
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 # Make sure listed files do not contain "unwrap"
 
 set -o errexit
 set -o nounset
 set -o pipefail
 
-cd "$(git rev-parse --show-toplevel)" # cd into repo root so make sure paths works in any case
+# cd into repo root to make sure paths work in any case
+cd "$(git rev-parse --show-toplevel)"
 
 # files that should not contain "unwrap"
 FILES=("components/compositing/compositor.rs"

etc/ci/lockfile_changed.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 set -o errexit
 set -o nounset
 set -o pipefail

etc/ci/manifest_changed.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 set -o errexit
 set -o nounset
 set -o pipefail
@@ -7,8 +11,8 @@ set -o pipefail
 # We shouldn't need any binary at all to update the manifests.
 # Adding "SKIP_TESTS" to skip tests, it doesn't really skip the tests.
 # It will run "run_wpt" with "'test_list': ['SKIP_TESTS']",
-# and then pass it into wptrunner, which won't be able to find any tests named "SKIP_TESTS",
-# and thus won't run any.
+# and then pass it into wptrunner, which won't be able to find any tests named
+# "SKIP_TESTS", and thus won't run any.
 # Adding "--binary=" to skip looking for a compiled servo binary.
 ./mach test-wpt --manifest-update --binary= SKIP_TESTS > /dev/null
 

etc/ci/upload_docs.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
-#
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 # Helper script to upload docs to doc.servo.org.
 # Requires ghp-import (from pip)
 # GitHub API token must be passed in environment var TOKEN
@@ -16,7 +20,8 @@ cp etc/doc.servo.org/* target/doc/
 
 python components/style/properties/build.py servo html
 
-OUT_DIR="`pwd`/target/doc/servo" make -f makefile.cargo -C components/script dom_docs
+OUT_DIR="$(pwd)/target/doc/servo" \
+  make -f makefile.cargo -C components/script dom_docs
 rm -rf target/doc/servo/.cache
 
 ghp-import -n target/doc

etc/ci/upload_nightly.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 set -o errexit
 set -o nounset
 set -o pipefail
@@ -12,7 +16,7 @@ usage() {
 
 
 upload() {
-    local package_filename 
+    local package_filename
     package_filename="$(basename "${2}")"
     local -r nightly_upload_dir="s3://servo-builds/nightly/${1}"
     local -r package_upload_path="${nightly_upload_dir}/${package_filename}"