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/pgp-lint.sh

@@ -6,7 +6,8 @@
 
 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 "${repo_toplevel}"
@@ -35,7 +36,7 @@ else
     find)
       files="$(find . -type f \( -name '*.asc' -o -name '*.gpg' \) | sort -d)"
       ;;
-    *) echo "Unsupported find tool" >&2; exit 1;;
+    *) printf '%s\n' "Unsupported find tool" >&2; exit 1;;
   esac
 fi
 
@@ -46,14 +47,14 @@ fi
 for key in ${files}; do
   data="$(gpg --no-keyring --no-auto-check-trustdb --no-autostart \
     --with-colons --show-keys "${key}")"
-  nr="$(echo "${data}" | grep -Ec -e '^(p|s)ub:')"
+  nr="$(printf '%s\n' "${data}" | grep -Ec -e '^(p|s)ub:')"
   ## Threshold in days.
   threshold="${PGP_LINT_THRESHOLD:-30}"
   tty_stderr=0
   if test -t 2; then
     tty_stderr=1
   fi
-  echo "${data}" | awk -v fail="0" -v key="${key}" -v nr="${nr}" \
+  printf '%s\n' "${data}" | awk -v fail="0" -v key="${key}" -v nr="${nr}" \
     -v threshold="${threshold}" -v now="${now}" -v color="${tty_stderr}" \
     -F ':' '
     BEGIN {