diff --git a/bin/git-browse b/bin/git-browse
index 961603d55..98f315bb1 100755
--- a/bin/git-browse
+++ b/bin/git-browse
@@ -17,12 +17,7 @@ if [[ $remote == "" ]]; then
     exit 1
 fi
 
-# get remote url
-remote_url=$(git remote get-url "$remote")
-
-if [[ $? -ne 0 ]]; then
-    exit $?
-fi
+remote_url=$(git remote get-url "$remote") || exit $?
 
 if [[ $remote_url = git@* ]]; then
     url=$(echo "$remote_url" | sed -E -e 's/:/\//' -e 's/\.git$//' -e 's/.*@(.*)/http:\/\/\1/')
diff --git a/bin/git-browse-ci b/bin/git-browse-ci
index a554e653f..a4173f59f 100755
--- a/bin/git-browse-ci
+++ b/bin/git-browse-ci
@@ -15,12 +15,7 @@ then
     exit 1
 fi
 
-remote_url=$(git remote get-url "${remote}")
-
-if [[ $? -ne 0 ]]
-then
-    exit $?
-fi
+remote_url=$(git remote get-url "${remote}") || exit $?
 
 if [[ $remote_url = git@* ]]
 then
diff --git a/bin/git-brv b/bin/git-brv
index f2d83ab31..7b46b12a4 100755
--- a/bin/git-brv
+++ b/bin/git-brv
@@ -59,4 +59,4 @@ for b in "${ordered[@]}"; do
            "$color_branch_upstream" "-$uwidth" "${upstream[$b]}" "$reset" \
            "$color_diff_commit" "-$hwidth" "${hash[$b]}" "$reset" \
            "$msg"
-done
\ No newline at end of file
+done
diff --git a/bin/git-bulk b/bin/git-bulk
index 0a1da3d71..ff3021fa9 100755
--- a/bin/git-bulk
+++ b/bin/git-bulk
@@ -25,7 +25,7 @@ usage() {
 # add another workspace to global git config
 function addworkspace {
 	git config --global bulkworkspaces."$wsname" "$wsdir";
-	if [ ! -z "$source" ]; then
+	if [ -n "$source" ]; then
         if [ ! -d "$wsdir" ]; then echo 1>&2 "Path of workspace doesn't exist, make it first."; exit 1; fi
         regex='http(s)?://|ssh://|(git@)?.*:.*/.*'
         if [[ "$source" =~ $regex ]]; then
@@ -118,7 +118,7 @@ function wsnameToCurrent () {
 
 # helper to check number of arguments.
 function allowedargcount () {
-	if [ $paramcount -ne $1  ] && [ $paramcount -ne $2 ]; then
+	if [ "$paramcount" -ne "$1"  ] && [ "$paramcount" -ne "$2" ]; then
 		echo 1>&2 "error: wrong number of arguments" && usage;
 		exit 1;
 	fi
@@ -137,11 +137,11 @@ function executBulkOp () {
 
     allGitFolders=( $(eval find -L . -name ".git") )
 
-    for line in ${allGitFolders[@]}; do
+    for line in "${allGitFolders[@]}"; do
       local gitrepodir=${line::${#line}-5} # cut the .git part of find results to have the root git directory of that repository
       eval cd "\"$gitrepodir\"" # into git repo location
       local curdir=$PWD
-      local leadingpath=${curdir#${actual}}
+      local leadingpath=${curdir#"${actual}"}
       guardedExecution "$@"
       eval cd "\"$rwsdir\"" # back to origin location of last find command
     done
diff --git a/bin/git-changelog b/bin/git-changelog
index 482381ee7..0d1753fe6 100755
--- a/bin/git-changelog
+++ b/bin/git-changelog
@@ -233,7 +233,7 @@ commitList() {
   # fetch our tags
   local _ref _date _tag _tab='%x09'
   local _tag_regex='tag: *'
-  while IFS=$'\t' read _ref _date _tag; do
+  while IFS=$'\t' read -r _ref _date _tag; do
     [[ -z "${_tag}" ]] && continue
     # strip out tags form ()
     # git v2.2.0+ supports '%D', like '%d' without the " (", ")" wrapping. One day we should use it instead.
@@ -376,7 +376,7 @@ _exit() {
   # so we need to calculate the total column number(COL_NUM) of header first.
   # Why don't we just use the last column?
   # Because the body of CMD column may contain space and be treated as multiple fields.
-  pid_list=( $(ps -f | 
+  pid_list=( $(ps -f |
     awk -v ppid=$$ 'NR == 1 {
       COL_NUM = NF
     }
@@ -391,7 +391,7 @@ _exit() {
   local _pid
   for _pid in "${pid_list[@]}"; do
     echo "killing: ${_pid}"
-    kill -TERM ${_pid}
+    kill -TERM "${_pid}"
   done
 
   wait; stty sane; exit 1
@@ -474,10 +474,10 @@ main() {
     esac
     shift
   done
-  
+
   # The default log format unless already set
   [[ -z "$CUR_GIT_LOG_FORMAT" ]] && CUR_GIT_LOG_FORMAT="$GIT_LOG_FORMAT"
-  
+
   local _tag="$(_valueForKeyFakeAssocArray "start_tag" "${option[*]}")"
   local start_commit="$(_valueForKeyFakeAssocArray "start_commit" "${option[*]}")"
 
@@ -487,7 +487,6 @@ main() {
       return 1
     fi
 
-    start_commit="$start_commit"
     start_tag="$(git describe --tags --contains "$start_commit" 2>/dev/null || echo 'null')"
     if [[ -z "$start_tag" ]]; then
       _error "Could find the associative tag for the start-commit!"
@@ -569,12 +568,11 @@ main() {
   else
     cp -f "$tmpfile" "$changelog"
     rm -f "$tmpfile"
-    # Use `eval` to handle GIT_EDITOR which contains space and options,
-    # like ""C:\Program Files (x86)\Notepad++\notepad++.exe" -multiInst ".
-    # Thanks @JanSchulz to inspire me this solution
-    [[ -n "$GIT_EDITOR" ]] && eval $GIT_EDITOR "$changelog"
-    if [[ $? -ne 0 ]]; then
-      _exit
+
+    if [[ -n "$GIT_EDITOR" ]]; then
+      $GIT_EDITOR "$changelog" || _exit
+    else
+      less "$changelog" || _exit
     fi
   fi
 
diff --git a/bin/git-delete-merged-branches b/bin/git-delete-merged-branches
index da93bafa5..f5c4f7731 100755
--- a/bin/git-delete-merged-branches
+++ b/bin/git-delete-merged-branches
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-branches=$(git branch --no-color --merged | grep -vE "^(\*|\+)" | grep -v $(git_extra_default_branch) | grep -v svn)
+branches=$(git branch --no-color --merged | grep -vE "^(\*|\+)" | grep -v "$(git_extra_default_branch)" | grep -v svn)
 if [ -n "$branches" ]
 then
     echo "$branches" | xargs -n 1 git branch -d
diff --git a/bin/git-delete-squashed-branches b/bin/git-delete-squashed-branches
index 94b5eb7e7..6245b6b30 100755
--- a/bin/git-delete-squashed-branches
+++ b/bin/git-delete-squashed-branches
@@ -12,7 +12,7 @@ fi
 git for-each-ref refs/heads/ "--format=%(refname:short)" | while read -r branch; do
     mergeBase=$(git merge-base "$targetBranch" "$branch")
 
-    if [[ $(git cherry "$targetBranch" $(git commit-tree $(git rev-parse $branch\^{tree}) -p $mergeBase -m _)) == "-"* ]]; then
+    if [[ $(git cherry "$targetBranch" "$(git commit-tree "$(git rev-parse "$branch^{tree}")" -p "$mergeBase" -m _)") == "-"* ]]; then
         git branch -D "$branch"
     fi
 done
diff --git a/bin/git-delete-tag b/bin/git-delete-tag
index fbb554515..2c738f1a7 100755
--- a/bin/git-delete-tag
+++ b/bin/git-delete-tag
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 # Assert there is at least one tag provided
-test -z $1 && echo "tag required." 1>&2 && exit 1
+test -z "$1" && echo "tag required." 1>&2 && exit 1
 
 # Detect the default remote exists or not
 default_remote=$(git config git-extras.default-remote)
diff --git a/bin/git-effort b/bin/git-effort
index 152ef5b92..32edd3fce 100755
--- a/bin/git-effort
+++ b/bin/git-effort
@@ -59,14 +59,14 @@ active_days() {
 
 color_for() {
   if [ "$to_tty" = true ]; then
-    if   [ $1 -gt 200 ]; then color="$(tputq setaf 1)$(tputq bold)"
-    elif [ $1 -gt 150 ]; then color="$(tputq setaf 1)"  # red
-    elif [ $1 -gt 125 ]; then color="$(tputq setaf 2)$(tputq bold)"
-    elif [ $1 -gt 100 ]; then color="$(tputq setaf 2)"  # green
-    elif [ $1 -gt 75 ]; then color="$(tputq setaf 5)$(tputq bold)"
-    elif [ $1 -gt 50 ]; then color="$(tputq setaf 5)"  # purplish
-    elif [ $1 -gt 25 ]; then color="$(tputq setaf 3)$(tputq bold)"
-    elif [ $1 -gt 10 ]; then color="$(tputq setaf 3)"  # yellow
+    if   [ "$1" -gt 200 ]; then color="$(tputq setaf 1)$(tputq bold)"
+    elif [ "$1" -gt 150 ]; then color="$(tputq setaf 1)"  # red
+    elif [ "$1" -gt 125 ]; then color="$(tputq setaf 2)$(tputq bold)"
+    elif [ "$1" -gt 100 ]; then color="$(tputq setaf 2)"  # green
+    elif [ "$1" -gt 75 ]; then color="$(tputq setaf 5)$(tputq bold)"
+    elif [ "$1" -gt 50 ]; then color="$(tputq setaf 5)"  # purplish
+    elif [ "$1" -gt 25 ]; then color="$(tputq setaf 3)$(tputq bold)"
+    elif [ "$1" -gt 10 ]; then color="$(tputq setaf 3)"  # yellow
     else color="$(tputq sgr0)" # default color
     fi
   else
@@ -84,20 +84,21 @@ effort() {
     local color reset_color commits len dot f_dot i msg active
     reset_color=""
     test "$to_tty" = true && reset_color="$(tputq sgr0)"
-    commit_dates=$(dates "$path")
-    [ $? -gt 0 ] && exit 255
+    if ! commit_dates=$(dates "$path"); then
+      exit 255
+    fi
 
     # Ensure it's not just an empty line
-    if [ -z "$(head -c 1 <<<$(echo $commit_dates))" ]
+    if [ -z "$(head -c 1 <<<"$commit_dates")" ]
     then
       exit 0
     fi
 
-    commits=$(wc -l <<<"$(echo "$commit_dates")")
+    commits=$(wc -l <<<"$commit_dates")
     color='90'
 
     # ignore <= --above
-    test $commits -le $above && exit 0
+    test "$commits" -le "$above" && exit 0
 
     # commits
     color_for $(( commits - above ))
@@ -109,12 +110,12 @@ effort() {
       i=$((i+1))
     done
 
-    msg=$(printf "  ${color}%s %-10d" "$f_dot" $commits)
+    msg=$(printf "  ${color}%s %-10d" "$f_dot" "$commits")
 
     # active days
     active=$(active_days "$commit_dates")
     color_for $(( active - above ))
-    msg="$msg $(printf "${color} %d${reset_color}\n" $active)"
+    msg="$msg $(printf "${color} %d${reset_color}\n" "$active")"
     echo "$msg"
 }
 
diff --git a/bin/git-feature b/bin/git-feature
index 6b23e8991..7b1e726a1 100755
--- a/bin/git-feature
+++ b/bin/git-feature
@@ -17,7 +17,7 @@ do
       shift # shift -a|-alias
       branch_prefix=$1
     else
-      argv+=($1) # treat tail '-a' as <name>
+      argv+=("$1") # treat tail '-a' as <name>
     fi
     ;;
   -r|--remote )
@@ -37,7 +37,7 @@ do
     shift
     ;;
   * )
-    argv+=($1)
+    argv+=("$1")
     ;;
   esac
   shift
diff --git a/bin/git-force-clone b/bin/git-force-clone
index 62c15e16e..a4c4d3225 100755
--- a/bin/git-force-clone
+++ b/bin/git-force-clone
@@ -67,17 +67,17 @@ main() {
 
       # Delete all remotes
       for remote in $(git remote); do
-        git remote rm ${remote}
+        git remote rm "${remote}"
       done
 
       # Add origin
-      git remote add origin ${remote_url}
+      git remote add origin "${remote_url}"
       git fetch origin
 
       # Set default branch
       if [ -z "${branch:-}" ]; then
         branch=$(LC_ALL=C git remote show origin | grep -oP '(?<=HEAD branch: )[^ ]+$')
-        git remote set-head origin ${branch}
+        git remote set-head origin "${branch}"
       else
         git remote set-head origin -a
       fi
@@ -87,8 +87,8 @@ main() {
       git reset --hard HEAD
 
       # Get on the desired branch
-      git checkout ${branch}
-      git reset --hard origin/${branch}
+      git checkout "${branch}"
+      git reset --hard "origin/${branch}"
 
       # Delete all other branches
       branches=$(git branch | grep -v \* | xargs)
@@ -97,7 +97,7 @@ main() {
       fi
     )
   elif [ -n "${branch:-}" ]; then
-    git clone -b ${branch} "${remote_url}" "${destination_path}"
+    git clone -b "${branch}" "${remote_url}" "${destination_path}"
   else
     git clone "${remote_url}" "${destination_path}"
   fi
diff --git a/bin/git-fork b/bin/git-fork
index d274b55af..ba85283f6 100755
--- a/bin/git-fork
+++ b/bin/git-fork
@@ -35,13 +35,14 @@ fi
 [[ -z "$project" || -z "$owner" ]] && abort "github repo needs to be specified as an argument"
 
 # create fork
-curl -qsf \
+if ! curl -qsf \
   -X POST \
   -u "$user:$github_personal_access_token" \
   -H "X-GitHub-OTP: $MFA_CODE" \
   "https://api.github.com/repos/$owner/$project/forks"
-
-[ $? = 0 ] || abort "fork failed"
+then
+  abort "fork failed"
+fi
 
 echo "Add GitHub remote branch via SSH (you will be prompted to verify the server's credentials)? (y/n)"
 read -r use_ssh
diff --git a/bin/git-ignore-io b/bin/git-ignore-io
index fa5e40c6b..f18903bc1 100755
--- a/bin/git-ignore-io
+++ b/bin/git-ignore-io
@@ -46,12 +46,11 @@ search() {
 }
 
 print_last_modified_time() {
-    gi_list_date=$(stat -c "%y" "$default_path" 2> /dev/null)
-    if [ "$?" -ne 0 ]; then
-        gi_list_date=$(stat -f "%t%Sm" "$default_path" 2> /dev/null)
-        if [ "$?" -ne 0 ]; then
-            gi_list_date=$(date -r "$default_path" +%s 2> /dev/null)
-            [ "$?" -ne 0 ] && gi_list_date=0
+    if ! gi_list_date=$(stat -c "%y" "$default_path" 2> /dev/null); then
+        if ! gi_list_date=$(stat -f "%t%Sm" "$default_path" 2> /dev/null); then
+            if ! gi_list_date=$(date -r "$default_path" +%s 2> /dev/null); then
+                gi_list_date=0
+            fi
         fi
     fi
     echo "Last update time: $gi_list_date"
diff --git a/bin/git-pr b/bin/git-pr
index 3633d1c74..4ec209e53 100755
--- a/bin/git-pr
+++ b/bin/git-pr
@@ -12,10 +12,10 @@ pull() {
     ref="refs/pull/$id/merge"
   fi
 
-  git fetch -fu $remote $ref:$branch && \
-  git checkout $branch && \
-  git config --local --replace branch.$branch.merge $ref && \
-  git config --local --replace branch.$branch.remote $remote;
+  git fetch -fu "$remote" "$ref:$branch" && \
+  git checkout "$branch" && \
+  git config --local --replace "branch.$branch.merge" "$ref" && \
+  git config --local --replace "branch.$branch.remote" "$remote"
 }
 
 pull_pr_if_matched() {
@@ -54,8 +54,8 @@ done
 test -z "$1" && echo "pr number required." 1>&2 && exit 1
 
 if test "$1" = "clean"; then
-  git for-each-ref refs/heads/pr/* --format='%(refname)' | while read ref; do
-    git branch -D ${ref#refs/heads/}
+  git for-each-ref refs/heads/pr/* --format='%(refname)' | while read -r ref; do
+    git branch -D "${ref#refs/heads/}"
   done
 
 elif [[ "$1" =~ ^[0-9]+$ ]]; then
diff --git a/bin/git-psykorebase b/bin/git-psykorebase
index 2194714eb..778adcc38 100755
--- a/bin/git-psykorebase
+++ b/bin/git-psykorebase
@@ -50,7 +50,7 @@ fi
 
 if [[ "$CONTINUE" == "yes" ]]; then
     TARGET_BRANCH=$(current_branch)
-    set $(echo "$TARGET_BRANCH" | sed -e "s/-rebased-on-top-of-/\n/g")
+    set "$(echo "$TARGET_BRANCH" | sed -e "s/-rebased-on-top-of-/\n/g")"
     if [[ $# != 2 ]]; then
         echo "Couldn't continue rebasing on ${TARGET_BRANCH}"
         exit 30  # Impossible to detect PRIMARY_BRANCH AND SECONDARY_BRANCH
diff --git a/bin/git-scp b/bin/git-scp
index 668b82d17..7aa2131d4 100755
--- a/bin/git-scp
+++ b/bin/git-scp
@@ -18,7 +18,7 @@ function _test_git_scp()
 function set_remote()
 {
 	remote=$1
-	if [ $(git remote | grep -c -- ^$remote$) -eq 0 ]
+	if [ "$(git remote | grep -c -- "^$remote$")" -eq 0 ]
 	then
 		COLOR_RED
 		echo "Remote $remote does not exist in your git config"
@@ -39,8 +39,9 @@ function php_lint()
 		test ! -f "$i" && continue
 		case "$i" in
 			*\.php|*\.phtml)
-				php -l "$i" > /dev/null
-				[ $? -gt 0 ] && error_count[${#error_count[@]}]="$i"
+				if ! php -l "$i" > /dev/null; then
+					error_count[${#error_count[@]}]="$i"
+				fi
 			;;
 		esac
 	done
@@ -83,7 +84,7 @@ function scp_and_stage
 	if [ -n "$refhead" ]
 	then
 		shift
-		[ $(git branch --contains "$refhead" | grep -c '\*') -eq 0 ] &&
+		[ "$(git branch --contains "$refhead" | grep -c '\*')" -eq 0 ] &&
 			_error "refhead provided is not part of current branch"
 	fi
 
@@ -99,8 +100,8 @@ function scp_and_stage
 		list=$(git diff --name-only)
 	fi
 
-	deleted=$(for i in $list; do [ -f $i ] || echo $i; done)
-	   list=$(for i in $list; do [ -f $i ] && echo $i; done)
+	deleted=$(for i in $list; do [ -f "$i" ] || echo "$i"; done)
+	   list=$(for i in $list; do [ -f "$i" ] && echo "$i"; done)
 
 	if [ -n "$list" ]
 	then
@@ -113,12 +114,12 @@ function scp_and_stage
 		rm "$_TMP"
 	fi
 
-	deleted=$(for i in $deleted; do echo $(git config remote.$remote.url | cut -d: -f2)/$i; done)
+	deleted=$(for i in $deleted; do echo "$(git config "remote.$remote.url" | cut -d: -f2)/$i"; done)
 
 	[ -n "$deleted" ] &&
 	COLOR_RED &&
 	echo Deleted remote files &&
-	ssh $(git config remote.$remote.url | cut -d: -f1) -t "rm $deleted" &&
+	ssh "$(git config "remote.$remote.url" | cut -d: -f1)" -t "rm $deleted" &&
 	echo "$deleted"
 	COLOR_RESET
 }
diff --git a/bin/git-standup b/bin/git-standup
index 871c74d90..be6b198dd 100755
--- a/bin/git-standup
+++ b/bin/git-standup
@@ -210,7 +210,7 @@ GIT_LOG_COMMAND="git --no-pager log \
     --color=$COLOR
     --pretty=format:'$GIT_PRETTY_FORMAT'
     --date='$GIT_DATE_FORMAT'"
-if [[ ! -z "$MAX_COMMIT_NUM" ]]; then
+if [[ -n "$MAX_COMMIT_NUM" ]]; then
     GIT_LOG_COMMAND="$GIT_LOG_COMMAND --max-count=$MAX_COMMIT_NUM"
 fi
 
@@ -221,7 +221,7 @@ git_output() {
         for branch in $branches; do
             # shellcheck disable=SC2086
             if output=$(eval $GIT_LOG_COMMAND "$branch"); then
-                if [[ ! -z "$output" ]] ;  then
+                if [[ -n "$output" ]] ;  then
                     echo "${GREEN}${branch}${NORMAL}"
                     echo "$output"
                     echo ""
diff --git a/bin/git-summary b/bin/git-summary
index ef2dcf0c9..4a650b227 100755
--- a/bin/git-summary
+++ b/bin/git-summary
@@ -212,9 +212,9 @@ print_summary_by_line() {
 print_summary() {
   if [ "$OUTPUT_STYLE" == "tabular" ]; then
     tabular_headers="# Repo $SP Age $SP Last active $SP Active on $SP Commits $SP Uncommitted"
-    echo -e "$tabular_headers\n$project $SP $(repository_age) $SP $(last_active) $SP $(active_days $commit) days $SP $(commit_count $commit) $SP $(uncommitted_changes_count)" | column -t -s "$COLUMN_CMD_DELIMTER"
+    echo -e "$tabular_headers\n$project $SP $(repository_age) $SP $(last_active) $SP $(active_days "$commit") days $SP $(commit_count "$commit") $SP $(uncommitted_changes_count)" | column -t -s "$COLUMN_CMD_DELIMTER"
   elif [ "$OUTPUT_STYLE" == "oneline" ]; then
-    echo "$project / age: $(repository_age) / last active: $(last_active) / active on $(active_days $commit) days / commits: $(commit_count $commit) / uncommitted: $(uncommitted_changes_count)"
+    echo "$project / age: $(repository_age) / last active: $(last_active) / active on $(active_days "$commit") days / commits: $(commit_count "$commit") / uncommitted: $(uncommitted_changes_count)"
   else
     echo
     echo " project     : $project"
diff --git a/bin/git-undo b/bin/git-undo
index 47f8d4960..18689c03f 100755
--- a/bin/git-undo
+++ b/bin/git-undo
@@ -69,4 +69,4 @@ if [[ ! $parm2 =~ ^[1-9][0-9]*$ ]]; then
     exit 1
 fi
 
-_undo $parm1 $parm2 $parm3
+_undo "$parm1" "$parm2" "$parm3"
diff --git a/bin/git-utimes b/bin/git-utimes
index 321b5fc2d..2b76372ea 100755
--- a/bin/git-utimes
+++ b/bin/git-utimes
@@ -39,5 +39,5 @@ else
            <(git status -z --porcelain | tr '\0' '\n' | cut -c 4- | sort) \
   | cut -c ${#prefix}- \
   | tr '\n' '\0' \
-  | xargs -0 -P${NPROC:-1} -n 24 $opt_r git utimes --touch "$1"
+  | xargs -0 -P"${NPROC:-1}" -n 24 $opt_r git utimes --touch "$1"
 fi