diff --git a/README.md b/README.md
index 606d17b..a44e363 100644
--- a/README.md
+++ b/README.md
@@ -7,15 +7,15 @@ between presets.
 
 Switch on/off:
 
-`$ wled -f(nordcenter)|-w(wohnzimmer) on|off`
+`$ wled --fnordcenter|--wohnzimmer|--all on|off`
 
 Switch between presets 1 to 17 or list available presets:
 
-`$ wled -f|-w 1-17|l`
+`$ wled -f|-w|-a [1-17|l(ist)]`
 
 Change brightness:
 
-`$ wled -f|-w -b 1-255`
+`$ wled -f|-w|-a -b [1-255]`
 
 ## Requirements
 
diff --git a/wled b/wled
index 5811985..c99a225 100755
--- a/wled
+++ b/wled
@@ -8,21 +8,22 @@
 
 NAME="wled.sh"
 COMMAND="wled"
-VERSION="0.1.1"
+VERSION="0.1.2"
 
 print_usage() {
     echo "\
-Usage: $COMMAND -f(norcenter)|-w(wohnzimmer) [on|off]
-       $COMMAND -f|-w [1-17|list]
-       $COMMAND -f|-w -b [1-255]"
+Usage: $COMMAND -f(norcenter)|-w(wohnzimmer)|-a(ll) [on|off]
+       $COMMAND -f|-w|-a [1-17|list]
+       $COMMAND -f|-w|-a -b [1-255]"
 }
 
 print_help() {
     print_usage
     echo "
-host selection:
+instance selection:
     -f,--fnordcenter        select fnordcenter
     -w,--wohnzimmer         select wohnzimmer
+    -a,--all                select all known instances
 
 commands:
     on|off                  switch on/off
@@ -50,9 +51,16 @@ active_preset() {
         sed -n 's/.*"ps"[[:space:]]*:[[:space:]]*\(1\?[0-9]\).*/\1/p'
 }
 
-# Parse host argument.
-case "$1" in
-    ""|-h|--help) # Missing host parameter.
+arg_inst="$1"
+arg_cmnd="$2"
+arg_param="$3"
+
+# Clear positional arguments.
+set --
+
+# Parse instance argument and store hostnames as positional arguments.
+case "$arg_inst" in
+    ""|-h|--help) # Missing instance parameter.
         print_help
         exit 0
     ;;
@@ -60,93 +68,94 @@ case "$1" in
         echo "$NAME version $VERSION"
         exit 0
     ;;
+    -a|--all)
+        set -- 'wled-fnordcenter.local' \
+               'wled-wohnzimmer.local'
+    ;;
     -f|--fnordcenter)
-        wled_host='wled-fnordcenter.local'
+        set -- 'wled-fnordcenter.local'
     ;;
     -w|--wohnzimmer)
-        wled_host='wled-wohnzimmer.local'
+        set -- 'wled-wohnzimmer.local'
     ;;
-    *) # Unknown host parameter.
-        echo "Error: unknown host \"$1\"." >&2
+    *) # Unknown instance parameter.
+        echo "Error: unknown instance \"$arg_inst\"." >&2
         print_usage
         exit 1
     ;;
 esac
 
-# Parse and execute command argument.
-case "$2" in
-    on) # Switch on.
-        api_resp=$(curl_send '{"on":true}' "http://$wled_host/json")
-    ;;
-    off) # Switch off.
-        api_resp=$(curl_send '{"on":false}' "http://$wled_host/json")
-    ;;
-    -b|--brightness) # Set brightness.
-        if test -z "$3"; then
-            echo "Error: missing parameter for brightness." >&2
+# Parse and execute command argument against given instances.
+while test $# -gt 0; do
+    case "$arg_cmnd" in
+        on) # Switch on.
+            api_resp=$(curl_send '{"on":true}' "http://$1/json")
+        ;;
+        off) # Switch off.
+            api_resp=$(curl_send '{"on":false}' "http://$1/json")
+        ;;
+        -b|--brightness) # Set brightness.
+            if test -z "$arg_param"; then
+                echo "Error: missing parameter for brightness." >&2
+                exit 1
+            fi
+            # Try to convert 3rd parameter to an integer between 1 an 255.
+            bright=$(printf '%u' "$arg_param" 2>/dev/null)
+            if test $? -gt 0; then # Conversion failed.
+                echo "Error: unable to parse parameter for brightness." >&2
+                exit 1
+            elif test "$bright" -lt 1 -o "$bright" -gt 255; then
+                echo "Error: parameter for brightness is out of range." >&2
+                exit 1
+            fi
+            api_resp=$(curl_send "{'bri':$bright}" "http://$1/json")
+        ;;
+        [1-9]|1[0-7]) # Switch to preset.
+            api_resp=$(curl_send "{'ps':$arg_cmnd}" "http://$1/json")
+        ;;
+        l|list) # List presets.
+            printf "loading ...\r"
+            active_ps=$(active_preset "$1")
+            curl_fetch "http://$1/presets.json" | \
+                # Split into lines - one line per preset.
+                sed --sandbox 's/"1\?[0-9]"[[:space:]]*:/\n&/g' | \
+                # Extract number and name of every preset. Right-align numbers.
+                # Drop everything else.
+                sed --sandbox -n \
+                    '/^"\(1\?[0-9]\)"[[:space:]]*:.*"n"[[:space:]]*:[[:space:]]*"\([[:alnum:] _-]*\)".*$/{
+                        s//\1: \2/
+                        s/^[0-9]:/ &/
+                        p
+                    }' | \
+                # Sort.
+                sort -b -n | \
+                # Prepend description and mark active preset.
+                sed --sandbox -e "1i\\Presets on $1:" \
+                              -e "s/^ \?$active_ps:.*/& */"
+        ;;
+        "") # Missing command.
+            echo "Error: missing command." >&2
+            print_usage
             exit 1
-        fi
-        # Try to convert 3rd parameter to an integer between 1 an 255.
-        bright=$(printf '%u' "$3" 2>/dev/null)
-        if test $? -gt 0; then # Conversion failed.
-            echo "Error: unable to parse parameter for brightness." >&2
+        ;;
+        *) # Unknown command.
+            echo "Error: unknown command \"$arg_cmnd\"." >&2
+            print_usage
             exit 1
-        elif test "$bright" -lt 1 -o "$bright" -gt 255; then
-            echo "Error: parameter for brightness is out of range." >&2
-            exit 1
-        fi
-        api_resp=$(curl_send "{'bri':$bright}" "http://$wled_host/json")
-    ;;
-    [1-9]|1[0-7]) # Switch to preset.
-        api_resp=$(curl_send "{'ps':$2}" "http://$wled_host/json")
-    ;;
-    l|list) # List presets.
-        printf "loading ...\r"
-        active_ps=$(active_preset "$wled_host")
-        curl_fetch "http://$wled_host/presets.json" | \
-            # Split into lines - one line per preset.
-            sed --sandbox 's/"1\?[0-9]"[[:space:]]*:/\n&/g' | \
-            # Extract number and name of every preset. Right-align numbers.
-            # Drop everything else.
-            sed --sandbox -n \
-                '/^"\(1\?[0-9]\)"[[:space:]]*:.*"n"[[:space:]]*:[[:space:]]*"\([[:alnum:] _-]*\)".*$/{
-                    s//\1: \2/
-                    s/^[0-9]:/ &/
-                    p
-                }' | \
-            # Sort.
-            sort -b -n | \
-            # Prepend description and mark active preset.
-            sed --sandbox -e "1i\\Presets on $wled_host:" \
-                          -e "s/^ \?$active_ps:.*/& */"
-        exit $?
-    ;;
-    dump) # Dump JSON response from API.
-        curl_fetch -w '\n' "http://$wled_host/json"
-        exit 0
-    ;;
-    "") # Missing command.
-        echo "Error: missing command." >&2
-        print_usage
-        exit 1
-    ;;
-    *) # Unknown command.
-        echo "Error: unknown command \"$2\"." >&2
-        print_usage
-        exit 1
-    ;;
-esac
+        ;;
+    esac
 
-# Check curl exit status
-curl_exit=$?
-if test $curl_exit -ne 0; then
-    echo "Error: curl exited with exit code $curl_exit." >&2
-    exit 1
-fi
+    # Check curl exit status
+    curl_exit=$?
+    if test $curl_exit -ne 0; then
+        echo "Error: curl exited with exit code $curl_exit." >&2
+    fi
 
-# Check API responce.
-if echo "$api_resp" | grep -qv '{\s*"success"\s*:\s*true\s*}'; then
-    echo "Error: unexpected responce from WLED API." >&2
-    exit 1
-fi
+    # Check API responce.
+    if test -n "$api_resp" && echo "$api_resp" | grep -qv '{\s*"success"\s*:\s*true\s*}'; then
+        echo "Warning: unexpected responce from WLED API." >&2
+    fi
+
+    shift
+done