fix: avoid echo usage

Echo can interpret operand as an option and checking every variable to
be echoed is troublesome while with printf, if the format specifier is
present before the operand, printing as string can be enforced.

scripts/unicode-lint.sh

@@ -8,7 +8,8 @@
 
 set -eu
 
-command -v git >/dev/null || { echo "Missing program: git" >&2; exit 1; }
+command -v git >/dev/null ||
+  { printf '%s\n' "Missing program: git" >&2; exit 1; }
 repo_toplevel="$(git rev-parse --show-toplevel)"
 test -d "${repo_toplevel}" || exit 1
 cd "${repo_toplevel}"
@@ -22,7 +23,7 @@ if test -n "${1-}"; then
   fi
 fi
 
-files="$(echo "${files}" | sort -u)"
+files="$(printf '%s\n' "${files}" | sort -u)"
 # shellcheck disable=SC2086
 unicode_match="$(grep -oPrHn --exclude-dir=.git --exclude-dir=LICENSES \
                   -e "[^\x00-\x7F]" -- ${files} || true)"
@@ -30,14 +31,14 @@ unicode_match="$(grep -oPrHn --exclude-dir=.git --exclude-dir=LICENSES \
 match_found=""
 if test -n "${unicode_match}"; then
   for line in ${unicode_match}; do
-    line_file="$(echo "${line}" | cut -d ":" -f1)"
+    line_file="$(printf '%s\n' "${line}" | cut -d ":" -f1)"
     case "${line_file}" in
       git/*|LICENSES/*|.reuse/dep5|*.asc) continue;;
       *) ;;
     esac
-    line_number="$(echo "${line}" | cut -d ":" -f2)"
-    line_unicode="$(echo "${line}" | cut -d ":" -f3 | od -A n -vt c)"
-    echo "${line_file}:${line_number}:${line_unicode}"
+    line_number="$(printf '%s\n' "${line}" | cut -d ":" -f2)"
+    line_unicode="$(printf '%s\n' "${line}" | cut -d ":" -f3 | od -A n -vt c)"
+    printf '%s\n' "${line_file}:${line_number}:${line_unicode}"
     match_found="1"
   done
   if test "${match_found}" = 1; then