Add ShellCheck to Circle CI config. (#569)

* Add shellcheck.

* Fix circleci config.

* Apply shellcheck recommendations.

* Fix check-bash.

* Globally ignore SC1091.

* Cleanup.

.circleci/config.yml

@@ -11,6 +11,17 @@ jobs:
       - run:
           name: Check that all text files end in a trailing newline
           command: ./dev-scripts/check-trailing-newline
+  check_bash:
+    docker:
+      - image: koalaman/shellcheck-alpine:v0.7.1
+    steps:
+      - run:
+          name: Install dependencies
+          command: apk add bash git openssh-client grep
+      - checkout
+      - run:
+          name: Run static analysis on bash scripts
+          command: ./dev-scripts/check-bash
   build_python:
     docker:
       - image: circleci/python:3.7.3
@@ -49,6 +60,7 @@ workflows:
   test:
     jobs:
       - check_whitespace
+      - check_bash
       - build_python
       - format_frontend
       - e2e

.shellcheckrc

@@ -0,0 +1,3 @@
+# Stop shellcheck from complaining about references to files that don't
+# exist. They'll exist in a production environment, so these flags are noise.
+disable=SC1091

CONTRIBUTING.md

@@ -10,6 +10,7 @@ The steps below show you how to quickly set up a development environment for Tin
 
 * Python 3.7 or higher
 * Node.js 13.x or higher
+* [shellcheck](https://github.com/koalaman/shellcheck#installing)
 
 ### Install packages
 

dev-scripts/build

@@ -11,5 +11,6 @@ set -u
 
 ./dev-scripts/check-trailing-whitespace
 ./dev-scripts/check-trailing-newline
+./dev-scripts/check-bash
 ./dev-scripts/build-python
 ./dev-scripts/check-frontend-format

dev-scripts/check-bash

@@ -0,0 +1,21 @@
+#!/bin/bash
+#
+# Run static analysis on bash scripts.
+
+# Exit on first failing command.
+set -e
+
+# Exit on unset variable.
+set -u
+
+BASH_SCRIPTS=()
+
+while read -r line; do
+  if head -n 1 "${line}" | grep --quiet "#!/bin/bash"; then
+    BASH_SCRIPTS+=("${line}")
+  fi
+done < <(git ls-files)
+
+readonly BASH_SCRIPTS
+
+shellcheck "${BASH_SCRIPTS[@]}"

dev-scripts/check-trailing-newline

@@ -7,23 +7,18 @@ set -e
 # Exit on unset variable.
 set -u
 
-readonly TEXT_FILES=$(grep \
-  ".*" \
-  --files-with-matches \
-  --binary-files=without-match \
-   --exclude="*.svg" \
-   --exclude="*third-party*" \
-   $(git ls-files | xargs)
-)
-
 success=0
 
-for text_file in ${TEXT_FILES[*]}
-do
-  if ! [[ -s "${text_file}" && -z "$(tail -c 1 "${text_file}")" ]]; then
-    printf "File must end in a trailing newline: ${text_file}\n" >&2
-    success=-1
+while read -r line; do
+  if ! [[ -s "${line}" && -z "$(tail -c 1 "${line}")" ]]; then
+    printf "File must end in a trailing newline: %s\n" "${line}" >&2
+    success=255
   fi
-done
+done < <(git ls-files \
+  | xargs grep ".*" \
+    --files-with-matches \
+    --binary-files=without-match \
+    --exclude="*.svg" \
+    --exclude="*third-party*")
 
 exit "${success}"

dev-scripts/check-trailing-whitespace

@@ -7,12 +7,15 @@ set -e
 # Exit on unset variable.
 set -u
 
-if grep \
-  "\s$" \
-  --line-number \
-  --binary-files=without-match \
-  --exclude="*third-party*" \
-  $(git ls-files | xargs); then
-  echo "ERROR: Found trailing whitespace";
-  exit 1;
-fi
+while read -r line; do
+  if grep \
+    "\s$" \
+    --line-number \
+    --with-filename \
+    --binary-files=without-match \
+    --exclude="*third-party*" \
+    "${line}"; then
+    echo "ERROR: Found trailing whitespace";
+    exit 1;
+  fi
+done < <(git ls-files)

e2e/docker-test

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # Echo commands to stdout.
 set -x

e2e/test

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # Echo commands to stdout.
 set -x

quick-install

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # Echo commands to stdout.
 set -x
@@ -69,7 +69,7 @@ readonly EXTRA_VARS_PATH
 # Check if the user is accidentally downgrading from TinyPilot Pro.
 HAS_PRO_INSTALLED=0
 
-SCRIPT_DIR="$(dirname $0)"
+SCRIPT_DIR="$(dirname "$0")"
 # If they're piping this script in from stdin, guess that TinyPilot is
 # in the default location.
 if [ "$SCRIPT_DIR" = "." ]; then
@@ -101,7 +101,7 @@ if [ "$HAS_PRO_INSTALLED" = 1 ]; then
     printf "type the following:\n\n"
     printf "  export FORCE_DOWNGRADE=1\n\n"
     printf "And then run your previous command again.\n"
-    exit -1
+    exit 255
   fi
 fi
 

scripts/upgrade

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # The canonical way to update is through the update script below,
 # but this file is here for backwards compatibility.