Fix shellcheck(1) warning SC2181

"Check exit code directly with e.g. 'if mycmd;', not indirectly with $?."

diff --git a/bin/backup-script b/bin/backup-script
index 9530410dee0e8d85b7e7b18ad9cefdba4d6cc00f..f2df4db98220e0b12472249e53a883c0ff0db2d0 100755 (executable)
--- a/bin/backup-script
+++ b/bin/backup-script
@@ -72,8 +72,7 @@ Usage() {
 CleanUp() {
        if [[ -n "$pre_exec" && $PREPOSTEXEC -ne 0 ]]; then
                echo "Executing \"$post_exec\" ..."
-               sh -c $post_exec
-               if [ $? -ne 0 ]; then
+               if ! sh -c $post_exec; then
                        echo "Warning: post-exec command failed!"
                fi
                echo
@@ -322,13 +321,11 @@ echo -n "Started: "; date
 echo -e "$config_info"
 
 # Check rsync and its protocol version
-rsync=$(which "rsync" 2>/dev/null)
-if [ $? -ne 0 ]; then
+if ! rsync=$(which "rsync" 2>/dev/null); then
        echo "Failed to detect rsync(1)! Is it installed in your \$PATH?"
        exit 1
 fi
-rsync_proto=$($rsync --version 2>/dev/null | head -n 1 | sed 's/.*  protocol version \([0-9]*\)$/\1/')
-if [ $? -ne 0 ]; then
+if ! rsync_proto=$($rsync --version 2>/dev/null | head -n 1 | sed 's/.*  protocol version \([0-9]*\)$/\1/'); then
        echo "Failed to detect protocol version of $rsync!"
        exit 1
 fi
@@ -351,8 +348,7 @@ fi
 
 if [[ -n "$setup_exec" && $PREPOSTEXEC -ne 0 ]]; then
        echo "Executing \"$setup_exec\" ..."
-       sh -c $setup_exec
-       if [ $? -ne 0 ]; then
+       if ! sh -c $setup_exec; then
                echo "Error: setup command failed!"; echo
                echo "Aborting backup."; echo
                exit 5
@@ -372,8 +368,7 @@ if [ -e "$PIDFILE" ]; then
        echo
        exit 4
 fi
-touch "$PIDFILE" 2>/dev/null
-if [ $? -ne 0 ]; then
+if ! touch "$PIDFILE" 2>/dev/null; then
        echo "Warning: can't create PID file \"$PIDFILE\"!"
        echo
 else
@@ -382,8 +377,7 @@ fi
 
 if [[ -n "$pre_exec" && $PREPOSTEXEC -ne 0 ]]; then
        echo "Executing \"$pre_exec\" ..."
-       sh -c $pre_exec
-       if [ $? -ne 0 ]; then
+       if ! sh -c $pre_exec; then
                echo "Error: pre-exec command failed!"; echo
                CleanUp
                echo "Aborting backup."; echo
@@ -464,8 +458,7 @@ for f in "${sys[@]}"; do
        [[ "$local" -eq 1 ]] && tags="$tags,LOCAL"
        # Check tags
        if [[ -n "$TAG" && "$TAG" != "ALL" ]]; then
-               echo "$tags" | grep -E "(^|,)$TAG(,|$)" >/dev/null 2>&1
-               if [ $? -ne 0 ]; then
+               if ! echo "$tags" | grep -E "(^|,)$TAG(,|$)" >/dev/null 2>&1; then
                        if [ "$DRYRUN" -ne 0 ]; then
                                echo "Tags of system \"$system\" don't match \"$TAG\": \"$tags\". Skipped."
                                echo
@@ -520,11 +513,11 @@ for f in "${sys[@]}"; do
        sys_root="$sys_target"
        if [[ "$DRYRUN" -eq 0 && ! -e "$sys_target" ]]; then
                if [ $generations -gt 0 ]; then
-                       CreateSubvolume "$sys_target"
+                       CreateSubvolume "$sys_target"; r=$?
                else
-                       mkdir -p "$sys_target"
+                       mkdir -p "$sys_target"; r=$?
                fi
-               if [ $? -ne 0 ]; then
+               if [ $r -ne 0 ]; then
                        echo "Can't create \"$sys_target\"!? \"$system\" skipped!"
                        echo; continue
                fi
@@ -532,8 +525,7 @@ for f in "${sys[@]}"; do
 
        if [[ "$local" -eq 0 && "$ping" -ne 0 ]]; then
                # Check if system is alive
-               ping -c 1 "$system" >/dev/null 2>&1
-               if [ $? -ne 0 ]; then
+               if ! ping -c 1 "$system" >/dev/null 2>&1; then
                        echo "Host \"$system\" seems not to be alive!? Skipped."
                        echo; continue
                fi
@@ -554,8 +546,7 @@ for f in "${sys[@]}"; do
                if [[ -n "$last" && ! -e "$last/.stamp" ]]; then
                        # Old backup directory without "stamp file", continue
                        echo "Found incomplete snapshot in \"$last\", reusing and renaming it ..."
-                       RenameSubvolume "$last" "$sys_target"
-                       if [ $? -ne 0 ]; then
+                       if ! RenameSubvolume "$last" "$sys_target"; then
                                echo "Failed to rename last snapshot \"$last\" to \"$sys_target\"!? \"$system\" skipped!"
                                echo; continue
                        fi
@@ -724,9 +715,8 @@ for f in "${sys[@]}"; do
                                # shellcheck disable=SC2086
                                echo "Removing backup from" $last "..."
                                if [ "$DRYRUN" -eq 0 ]; then
-                                       DeleteSubvolume "$dir"
-                                       [ $? -eq 0 ] || \
-                                         echo "Failed to delete \"$dir\"!"
+                                       DeleteSubvolume "$dir" \
+                                               || echo "Failed to delete \"$dir\"!"
                                fi
                        done
                        echo -n "Clean up finished: "; date