diff --git a/tools/tools/git/git-arc.sh b/tools/tools/git/git-arc.sh
--- a/tools/tools/git/git-arc.sh
+++ b/tools/tools/git/git-arc.sh
@@ -34,7 +34,7 @@
 
 warn()
 {
-    echo "$(basename "$0"): $1" >&2
+    printf '%s\n' "$(basename "$0"): $1" >&2
 }
 
 err()
@@ -154,7 +154,7 @@
 #
 get_bool_config()
 {
-    test "$(git config --bool --get "$1" 2>/dev/null || echo "$2")" != "false"
+    test "$(git config --bool --get "$1" 2>/dev/null || printf '%s\n' "$2")" != "false"
 }
 
 #
@@ -186,7 +186,7 @@
         err "invalid diff ID $diff"
     fi
 
-    echo '{"names":["'"$diff"'"]}' |
+    printf '%s\n' '{"names":["'"$diff"'"]}' |
         arc_call_conduit -- phid.lookup |
         jq -r "select(.response != []) | .response.${diff}.phid"
 }
@@ -201,7 +201,7 @@
     fi
 
     tmp=$(mktemp)
-    echo '{"names":["'"$diff"'"]}' |
+    printf '%s\n' '{"names":["'"$diff"'"]}' |
         arc_call_conduit -- phid.lookup > "$tmp"
     status=$(jq -r "select(.response != []) | .response.${diff}.status" < "$tmp")
     summary=$(jq -r "select(.response != []) |
@@ -215,10 +215,10 @@
 
     diff=$(git show -s --format=%B "$commit" |
         sed -nE '/^Differential Revision:[[:space:]]+(https:\/\/reviews.freebsd.org\/)?(D[0-9]+)$/{s//\2/;p;}')
-    if [ -n "$diff" ] && [ "$(echo "$diff" | wc -l)" -eq 1 ]; then
-        echo "$diff"
+    if [ -n "$diff" ] && [ "$(printf '%s\n' "$diff" | wc -l)" -eq 1 ]; then
+        printf '%s\n' "$diff"
     else
-        echo
+        printf '\n'
     fi
 }
 
@@ -228,7 +228,7 @@
 {
     local title
 
-    title=$(echo "$1" | sed 's/"/\\"/g')
+    title=$(printf '%s\n' "$1" | sed 's/"/\\"/g')
     arc_list --no-ansi |
         awk -F': ' '{
             if (substr($0, index($0, FS) + length(FS)) == "'"$title"'") {
@@ -247,7 +247,7 @@
     # log.
     diff=$(log2diff "$commit")
     if [ -n "$diff" ]; then
-        echo "$diff"
+        printf '%s\n' "$diff"
         return
     fi
 
@@ -257,11 +257,11 @@
     diff=$(title2diff "$title")
     if [ -z "$diff" ]; then
         err "could not find review for '${title}'"
-    elif [ "$(echo "$diff" | wc -l)" -ne 1 ]; then
+    elif [ "$(printf '%s\n' "$diff" | wc -l)" -ne 1 ]; then
         err "found multiple reviews with the same title"
     fi
 
-    echo "$diff"
+    printf '%s\n' "$diff"
 }
 
 create_one_review()
@@ -298,7 +298,7 @@
 
         childphid=$(diff2phid "$diff")
         parentphid=$(diff2phid "$parent")
-        echo '{
+        printf '%s\n' '{
             "objectIdentifier": "'"${childphid}"'",
             "transactions": [
                 {
@@ -320,15 +320,15 @@
     diff=$1
     reviewid=$(diff2phid "$diff")
     userids=$( \
-        echo '{
+        printf '%s\n' '{
                   "constraints": {"phids": ["'"$reviewid"'"]},
                   "attachments": {"reviewers": true}
               }' |
         arc_call_conduit -- differential.revision.search |
         jq '.response.data[0].attachments.reviewers.reviewers[] | select(.status == "accepted").reviewerPHID')
     if [ -n "$userids" ]; then
-        echo '{
-                  "constraints": {"phids": ['"$(echo -n "$userids" | tr '[:space:]' ',')"']}
+        printf '%s\n' '{
+                  "constraints": {"phids": ['"$(printf '%s' "$userids" | tr '[:space:]' ',')"']}
               }' |
             arc_call_conduit -- user.search |
             jq -r '.response.data[].fields.username'
@@ -379,7 +379,7 @@
         [ -n "$_commits" ] || err "invalid commit ID ${chash}"
         commits="$commits $_commits"
     done
-    echo "$commits"
+    printf '%s\n' "$commits"
 }
 
 gitarc__create()
@@ -444,7 +444,7 @@
 
     for commit in $commits; do
         chash=$(git show -s --format='%C(auto)%h' "$commit")
-        echo -n "${chash} "
+        printf '%s' "${chash} "
 
         diff=$(log2diff "$commit")
         if [ -n "$diff" ]; then
@@ -455,17 +455,17 @@
         # This does not use commit2diff as it needs to handle errors
         # differently and keep the entire status.
         title=$(git show -s --format=%s "$commit")
-        diff=$(echo "$openrevs" | \
+        diff=$(printf '%s\n' "$openrevs" | \
             awk -F'D[1-9][0-9]*: ' \
-                '{if ($2 == "'"$(echo "$title" | sed 's/"/\\"/g')"'") print $0}')
+                '{if ($2 == "'"$(printf '%s\n' "$title" | sed 's/"/\\"/g')"'") print $0}')
         if [ -z "$diff" ]; then
-            echo "No Review            : $title"
-        elif [ "$(echo "$diff" | wc -l)" -ne 1 ]; then
-            echo -n "Ambiguous Reviews: "
-            echo "$diff" | grep -E -o 'D[1-9][0-9]*:' | tr -d ':' \
+            printf '%s\n' "No Review            : $title"
+        elif [ "$(printf '%s\n' "$diff" | wc -l)" -ne 1 ]; then
+            printf '%s' "Ambiguous Reviews: "
+            printf '%s\n' "$diff" | grep -E -o 'D[1-9][0-9]*:' | tr -d ':' \
                 | paste -sd ',' - | sed 's/,/, /g'
         else
-            echo "$diff" | sed -e 's/^[^ ]* *//'
+            printf '%s\n' "$diff" | sed -e 's/^[^ ]* *//'
         fi
     done
 }
@@ -493,7 +493,7 @@
     case "${addr}" in
     *.*) ;;		# external user
     *)
-	echo "${name} <${addr}@FreeBSD.org>"
+	printf '%s\n' "${name} <${addr}@FreeBSD.org>"
 	return
 	;;
     esac
@@ -501,16 +501,16 @@
     # Choice 2: author_addr and author_name were set in the bundle, so use
     # that. We may need to filter some known bogus ones, should they crop up.
     if [ -n "$author_name" -a -n "$author_addr" ]; then
-	echo "${author_name} <${author_addr}>"
+	printf '%s\n' "${author_name} <${author_addr}>"
 	return
     fi
 
     # Choice 3: We can find this user in the FreeBSD repo. They've submited
     # something before, and they happened to use an email that's somewhat
     # similar to their phab username.
-    email=$(git log -1 --author "$(echo "${addr}" | tr _ .)" --pretty="%aN <%aE>")
+    email=$(git log -1 --author "$(printf '%s\n' "${addr}" | tr _ .)" --pretty="%aN <%aE>")
     if [ -n "${email}" ]; then
-	echo "${email}"
+	printf '%s\n' "${email}"
 	return
     fi
 
@@ -518,10 +518,10 @@
     # to use the same name, unless the name has the word 'user' in it. This
     # might not be a good idea, since names can be somewhat common (there
     # are two Andrew Turners that have contributed to FreeBSD, for example).
-    if ! (echo "${name}" | grep -w "[Uu]ser" -q); then
+    if ! (printf '%s\n' "${name}" | grep -w "[Uu]ser" -q); then
 	email=$(git log -1 --author "${name}" --pretty="%aN <%aE>")
 	if [ -n "$email" ]; then
-	    echo "$email"
+	    printf '%s\n' "$email"
 	    return
 	fi
     fi
@@ -531,13 +531,13 @@
     # Annoying fun fact: Phab replaces all non alpha-numerics with _, so we
     # don't know if the prior _ are _ or + or any number of other characters.
     # Since there's issues here, prompt
-    a=$(printf "%s <%s>\n" "${name}" $(echo "$addr" | sed -e 's/\(.*\)_/\1@/'))
-    echo "Making best guess: Truning ${addr} to ${a}"
+    a=$(printf "%s <%s>\n" "${name}" $(printf '%s\n' "$addr" | sed -e 's/\(.*\)_/\1@/'))
+    printf '%s\n' "Making best guess: Truning ${addr} to ${a}"
     if ! prompt; then
-       echo "ABORT"
+       printf '%s\n' "ABORT"
        return
     fi
-    echo "${a}"
+    printf '%s\n' "${a}"
 }
 
 patch_commit()
@@ -548,31 +548,31 @@
     diff=$1
     reviewid=$(diff2phid "$diff")
     # Get the author phid for this patch
-    review_data=$(echo '{
+    review_data=$(printf '%s\n' '{
                   "constraints": {"phids": ["'"$reviewid"'"]}
 		}' |
         arc_call_conduit -- differential.revision.search)
-    authorid=$(echo "$review_data" | jq -r '.response.data[].fields.authorPHID' )
+    authorid=$(printf '%s\n' "$review_data" | jq -r '.response.data[].fields.authorPHID' )
     # Get metadata about the user that submitted this patch
-    user_data=$(echo '{
+    user_data=$(printf '%s\n' '{
                   "constraints": {"phids": ["'"$authorid"'"]}
 		}' |
             arc call-conduit -- user.search | grep -v ^Warning: |
             jq -r '.response.data[].fields')
-    user_addr=$(echo "$user_data" | jq -r '.username')
-    user_name=$(echo "$user_data" | jq -r '.realName')
+    user_addr=$(printf '%s\n' "$user_data" | jq -r '.username')
+    user_name=$(printf '%s\n' "$user_data" | jq -r '.realName')
     # Dig the data out of querydiffs api endpoint, although it's deprecated,
     # since it's one of the few places we can get email addresses. It's unclear
     # if we can expect multiple difference ones of these. Some records don't
     # have this data, so we remove all the 'null's. We sort the results and
     # remove duplicates 'just to be sure' since we've not seen multiple
     # records that match.
-    diff_data=$(echo '{
+    diff_data=$(printf '%s\n' '{
 		"revisionIDs": [ '"${diff#D}"' ]
 		}' | arc_call_conduit -- differential.querydiffs |
 	     jq -r '.response | flatten | .[]')
-    author_addr=$(echo "$diff_data" | jq -r ".authorEmail?" | sort -u)
-    author_name=$(echo "$diff_data" | jq -r ".authorName?" | sort -u)
+    author_addr=$(printf '%s\n' "$diff_data" | jq -r ".authorEmail?" | sort -u)
+    author_name=$(printf '%s\n' "$diff_data" | jq -r ".authorName?" | sort -u)
     author=$(find_author "$user_addr" "$user_name" "$author_addr" "$author_name")
 
     # If we had to guess, and the user didn't want to guess, abort
@@ -582,10 +582,10 @@
     fi
 
     tmp=$(mktemp)
-    echo "$review_data" | jq -r '.response.data[].fields.title' > $tmp
-    echo >> $tmp
-    echo "$review_data" | jq -r '.response.data[].fields.summary' >> $tmp
-    echo >> $tmp
+    printf '%s\n' "$review_data" | jq -r '.response.data[].fields.title' > $tmp
+    printf '\n' >> $tmp
+    printf '%s\n' "$review_data" | jq -r '.response.data[].fields.summary' >> $tmp
+    printf '\n' >> $tmp
     # XXX this leaves an extra newline in some cases.
     reviewers=$(diff2reviewers "$diff" | sed '/^$/d' | paste -sd ',' - | sed 's/,/, /g')
     if [ -n "$reviewers" ]; then
@@ -621,7 +621,7 @@
 
     for rev in "$@"; do
         arc patch --skip-dependencies --nocommit --nobranch --force "$rev"
-        echo "Applying ${rev}..."
+        printf '%s\n' "Applying ${rev}..."
         [ $? -eq 0 ] || break
 	if ${commit}; then
 	    patch_commit $rev