Fix shellcheck(1) warning SC2181: "Check exit code directly"

See <https://github.com/koalaman/shellcheck/wiki/SC2181> for details.

diff --git a/bin/backup-audit b/bin/backup-audit
index 1aa83a7e17bc16091e11ec7d2812ad3e27008580..6785adc5e9089467cf3c4fc132a091de15b1c1b7 100755 (executable)
--- a/bin/backup-audit
+++ b/bin/backup-audit
@@ -212,8 +212,7 @@ DiffGenerations() {
                        [[ -r "${gen1_d}${file}" ]] || continue
 
                        [[ $VERBOSE -ne 0 ]] && echo "Checking \"$file\" ..."
-                       diff -U 3 "${gen1_d}${file}" "${gen2_d}${file}" >"$tmp_diff"
-                       if [[ $? -ne 0 ]]; then
+                       if ! diff -U 3 "${gen1_d}${file}" "${gen2_d}${file}" >"$tmp_diff"; then
                                BeginDiff "\"$file\""
                                tail -n +3 "$tmp_diff" | PipeDiff
                                EndDiff
@@ -241,8 +240,7 @@ DiffGenerations() {
                        [[ $VERBOSE -ne 0 ]] && echo "Checking \"$dir\" ..."
                        ListDirectory "${gen1_d}" "${dir}" >"$tmp_1"
                        ListDirectory "${gen2_d}" "${dir}" >"$tmp_2"
-                       diff -U 0 "$tmp_1" "$tmp_2" >"$tmp_diff"
-                       if [[ $? -ne 0 ]]; then
+                       if ! diff -U 0 "$tmp_1" "$tmp_2" >"$tmp_diff"; then
                                BeginDiff "\"$dir\" directory"
                                tail -n +3 "$tmp_diff" | egrep -v '^@@ ' | PipeDiff
                                EndDiff
@@ -254,8 +252,7 @@ DiffGenerations() {
                        [[ $VERBOSE -ne 0 ]] && echo "Checking list of installed packages ..."
                        chroot "${gen1_d}" dpkg --get-selections >"$tmp_1" || return 2
                        chroot "${gen2_d}" dpkg --get-selections >"$tmp_2" || return 2
-                       diff -U 0 "$tmp_1" "$tmp_2" >"$tmp_diff"
-                       if [[ $? -ne 0 ]]; then
+                       if ! diff -U 0 "$tmp_1" "$tmp_2" >"$tmp_diff"; then
                                BeginDiff "list of installed packages"
                                tail -n +3 "$tmp_diff" | grep -v '^@@ ' | PipeDiff
                                EndDiff
@@ -266,8 +263,7 @@ DiffGenerations() {
                # scp Backup type
                file=$(basename "$files")
                [[ $VERBOSE -ne 0 ]] && echo "Checking \"$file\" ..."
-               diff -U 3 "${gen1_d}/${file}" "${gen2_d}/${file}" >"$tmp_diff"
-               if [[ $? -ne 0 ]]; then
+               if ! diff -U 3 "${gen1_d}/${file}" "${gen2_d}/${file}" >"$tmp_diff"; then
                        BeginDiff "\"$file\""
                        tail -n +3 "$tmp_diff" | PipeDiff
                        EndDiff
@@ -340,8 +336,8 @@ for f in "${sys[@]}"; do
                        ;;
        esac
 
-       HandleSystem "$fname" >"$tmp_out" 2>&1
-       [[ $QUIET -eq 0 || $? -ne 0 ]] && cat "$tmp_out"
+       HandleSystem "$fname" >"$tmp_out" 2>&1; result=$?
+       [[ $QUIET -eq 0 || $result -ne 0 ]] && cat "$tmp_out"
 done
 CleanUp