feat(shellcheck): apply fixes throughout this repo

pre-commit_semantic-release.sh

@@ -14,9 +14,9 @@ sed -i -e "s_^\(version:\).*_\1 ${1}_" FORMULA
 sudo -H pip install m2r
 
 # Copy and then convert the `.md` docs
-cp *.md docs/
-cd docs/
-m2r --overwrite *.md
+cp ./*.md docs/
+cd docs/ || exit
+m2r --overwrite ./*.md
 
 # Change excess `H1` headings to `H2` in converted `CHANGELOG.rst`
 sed -i -e '/^=.*$/s/=/-/g' CHANGELOG.rst

ssf/files/default/git/git_10_prepare.sh

@@ -14,23 +14,23 @@ COMMENT='Command `'${STATE}'` run'
 # Check if PR branch already exists
 BRANCH=$(git branch -l "${BRANCH_PR}")
 COMMIT=
-if [ ! -z "${BRANCH}" ]; then
-    git checkout ${BRANCH_PR}
+if [ -n "${BRANCH}" ]; then
+    git checkout "${BRANCH_PR}"
     # This may end up as blank as well, so that's why a separate `if` is required below
     COMMIT=$(git log -n1 | grep "${COMMIT_GREP}")
 fi
 
 # Perform actions depending on if a commit was found or not
-if [ ! -z "${COMMIT}" ]; then
+if [ -n "${COMMIT}" ]; then
     CHANGED='False'
 else
-    git checkout ${BRANCH_UPSTREAM}
+    git checkout "${BRANCH_UPSTREAM}"
     git pull
     git status
     # If the branch existed but not the commit, assume the branch is stale (i.e. previous PR merged)
     # Remove it, ready to be recreated at the latest upstream commit
-    if [ ! -z "${BRANCH}" ]; then
-        git branch -d ${BRANCH_PR}
+    if [ -n "${BRANCH}" ]; then
+        git branch -d "${BRANCH_PR}"
     fi
     # TODO: Improve this part, should be able to remove with the duplication with the right solution
     # Don't want to resort to using `git branch -D` above, since that could be premature in certain situations
@@ -40,8 +40,10 @@ else
     if [ -z "${BRANCH}" ]; then
         NEW_BRANCH='-b'
     fi
-    git checkout ${NEW_BRANCH} ${BRANCH_PR}
-    git merge ${BRANCH_UPSTREAM}
+    # Disabling `SC2086` where double-quoting an empty variable introduces an error
+    # shellcheck disable=SC2086
+    git checkout ${NEW_BRANCH} "${BRANCH_PR}"
+    git merge "${BRANCH_UPSTREAM}"
 fi
 
 # Write the state line

ssf/files/default/git/git_20_commit_push.sh

@@ -10,10 +10,11 @@ COMMIT_GREP=${4}
 COMMIT_TITLE=${5}
 COMMIT_BODY=${6}
 COMMIT_OPTIONS=${7}
-PUSH_ACTIVE=$(echo ${8} | tr "[:upper:]" "[:lower:]")
-PUSH_VIA_PR=$(echo ${9} | tr "[:upper:]" "[:lower:]")
+PUSH_ACTIVE=$(echo "${8}" | tr "[:upper:]" "[:lower:]")
+PUSH_VIA_PR=$(echo "${9}" | tr "[:upper:]" "[:lower:]")
 REMOTE_FORK_NAME=${10}
-REMOTE_FORK_BRANCH=${11}
+# Currently unused but leaving here as a placeholder
+# REMOTE_FORK_BRANCH=${11}
 REMOTE_UPSTREAM_NAME=${12}
 REMOTE_UPSTREAM_BRANCH=${13}
 # Prepare initial state line variables
@@ -22,7 +23,7 @@ COMMENT='Command `'${STATE}'` run'
 
 # Prepare git options depending on if a commit was found or not
 COMMIT=$(git log -n1 | grep "${COMMIT_GREP}")
-if [ ! -z "${COMMIT}" ]; then
+if [ -n "${COMMIT}" ]; then
     AMEND='--amend'
     FORCE='-f'
 else
@@ -31,15 +32,18 @@ else
 fi
 
 # Perform actions
+# Disabling `SC2086` where double-quoting an empty variable introduces errors
+# shellcheck disable=SC2086
 git commit ${AMEND} "${COMMIT_OPTIONS}" -m "${COMMIT_TITLE}" -m "${COMMIT_BODY}"
 if ${PUSH_ACTIVE}; then
     if ${PUSH_VIA_PR}; then
-        git push ${FORCE} -u ${REMOTE_FORK_NAME} ${BRANCH_PR}
+        # shellcheck disable=SC2086
+        git push ${FORCE} -u "${REMOTE_FORK_NAME}" "${BRANCH_PR}"
     else
-        git checkout ${BRANCH_UPSTREAM}
-        git merge ${BRANCH_PR}
-        git push ${REMOTE_UPSTREAM_NAME} HEAD:${REMOTE_UPSTREAM_BRANCH}
-        git branch -d ${BRANCH_PR}
+        git checkout "${BRANCH_UPSTREAM}"
+        git merge "${BRANCH_PR}"
+        git push "${REMOTE_UPSTREAM_NAME}" "HEAD:${REMOTE_UPSTREAM_BRANCH}"
+        git branch -d "${BRANCH_PR}"
     fi
 fi
 

ssf/files/default/git/git_30_create_PR.sh

@@ -22,18 +22,18 @@ COMMENT='Command `'${STATE}'` run'
 
 # Only create the PR if it doesn't already exist
 # If it already exists, the `git push` done earlier will have updated the PR already
-PR_EXISTS=$(curl -i https://api.github.com/repos/${REPO_OWNER}/${REPO_NAME}/pulls | grep "${GH_USER}:${BRANCH_PR}")
-if [ ! -z "${PR_EXISTS}" ]; then
+PR_EXISTS=$(curl -i "https://api.github.com/repos/${REPO_OWNER}/${REPO_NAME}/pulls" | grep "${GH_USER}:${BRANCH_PR}")
+if [ -n "${PR_EXISTS}" ]; then
     CHANGED='False'
 else
     curl -H "Authorization: bearer ${GH_TOKEN}" -d '
         {
             "title": "'"${COMMIT_TITLE}"'",
             "body":  "'"${COMMIT_BODY}"'",
-            "head":  "'${GH_USER}':'${BRANCH_PR}'",
-            "base":  "'${REPO_BRANCH}'"
+            "head":  "'"${GH_USER}"':'"${BRANCH_PR}"'",
+            "base":  "'"${REPO_BRANCH}"'"
         }
-    ' https://api.github.com/repos/${REPO_OWNER}/${REPO_NAME}/pulls >> ${FILE_API_RESPONSE}
+    ' "https://api.github.com/repos/${REPO_OWNER}/${REPO_NAME}/pulls" >> "${FILE_API_RESPONSE}"
 fi
 
 # Write the state line

ssf/files/default/pre-commit_semantic-release.sh

@@ -14,9 +14,9 @@ sed -i -e "s_^\(version:\).*_\1 ${1}_" FORMULA
 sudo -H pip install m2r
 
 # Copy and then convert the `.md` docs
-cp *.md docs/
-cd docs/
-m2r --overwrite *.md
+cp ./*.md docs/
+cd docs/ || exit
+m2r --overwrite ./*.md
 
 # Change excess `H1` headings to `H2` in converted `CHANGELOG.rst`
 sed -i -e '/^=.*$/s/=/-/g' CHANGELOG.rst