diff --git a/run.sh b/run.sh
index d3a0a03..8a4c28c 100755
--- a/run.sh
+++ b/run.sh
@@ -4,10 +4,12 @@
 # CONSTANTS #
 #############
 
+# commands
 env_exe="$(command -v env)"
 ionice_exe="$(command -v ionice)"
 duplicity_exe="$(command -v duplicity)"
 
+# check if uses encryption
 if [ -n "${GPG_KEY_ID}" ]; then
     # gpg key given
     env_changes="PASSPHRASE='${GPG_PASSPHRASE}'"
@@ -22,91 +24,122 @@ fi
 # FUNCTIONS #
 #############
 
-trim_options() {
-    # if args are given, trim whitespace, then add a space in front
-    if [ -n "${1}" ]; then
-        echo " $( echo "${1}" | xargs )"
+append_options() {
+    ao_cmdline="${1}"
+    ao_options="${2}"
+    shift 1
+
+    # remove leading whitespace characters
+    ao_options="${ao_options#"${ao_options%%[![:space:]]*}"}"
+    # remove trailing whitespace characters
+    ao_options="${ao_options%"${ao_options##*[![:space:]]}"}"
+
+    # if options are given, stitch together with a space
+    if [ -n "${ao_options}" ]; then
+        echo "${ao_cmdline} ${ao_options}"
+    else
+        echo "${ao_cmdline}"
     fi
 }
 
 print_command() {
-    task="${1}"
+    pc_task="${1}"
     shift 1
 
+    # if environment should be changed, call with "env"
     if [ -n "${env_changes}" ]; then
-        # should change environment
-        cmdline="${env_exe} ${env_changes} "
+        pc_cmdline="${env_exe} ${env_changes} "
     else
-        cmdline=""
+        pc_cmdline=""
     fi
 
-    cmdline="${cmdline}${ionice_exe} -c 3 ${duplicity_exe} ${encrypt_opts}"
+    pc_cmdline="${pc_cmdline}${ionice_exe} -c 3 ${duplicity_exe} ${encrypt_opts}"
 
-    case "${task}" in
+    case "${pc_task}" in
         backup)
-            cmdline="${cmdline} --allow-source-mismatch --volsize '${BACKUP_VOLSIZE}' --full-if-older-than '${FULL_BACKUP_FREQUENCY}'"
-            cmdline="${cmdline}$( trim_options "${OPTIONS_BACKUP}" )"
-            cmdline="${cmdline} /backup/source"
+            pc_cmdline="${pc_cmdline} --allow-source-mismatch --volsize ${BACKUP_VOLSIZE} --full-if-older-than ${FULL_BACKUP_FREQUENCY}"
+            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_BACKUP} /backup/source" )"
             ;;
         
         cleanup)
-            cmdline="${cmdline} cleanup --force"
-            cmdline="${cmdline}$( trim_options "${OPTIONS_CLEAN}" )"
+            pc_cmdline="${pc_cmdline} cleanup --force"
+            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_CLEAN}" )"
             ;;
         
         rmfull)
-            cmdline="${cmdline} remove-older-than '${BACKUP_RETENTION_TIME}' --force"
-            cmdline="${cmdline}$( trim_options "${OPTIONS_RMFULL}" )"
+            pc_cmdline="${pc_cmdline} remove-older-than ${BACKUP_RETENTION_TIME} --force"
+            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_RMFULL}" )"
             ;;
         
         rmincr)
-            cmdline="${cmdline} remove-all-inc-of-but-n-full '${KEEP_NUM_FULL_CHAINS}' --force"
-            cmdline="${cmdline}$( trim_options "${OPTIONS_RMINCR}" )"
+            pc_cmdline="${pc_cmdline} remove-all-inc-of-but-n-full ${KEEP_NUM_FULL_CHAINS} --force"
+            pc_cmdline="$( append_options "${pc_cmdline}" "${OPTIONS_RMINCR}" )"
             ;;
     esac
 
-    cmdline="${cmdline} '${BACKUP_TARGET}'"
-    echo "${cmdline}"
+    pc_cmdline="${pc_cmdline} ${BACKUP_TARGET}"
+    echo "${pc_cmdline}"
 }
 
 print_cron_schedule() {
-    min="$(     echo "${1}" | cut -d' ' -f1 )"
-    hour="$(    echo "${1}" | cut -d' ' -f2 )"
-    day="$(     echo "${1}" | cut -d' ' -f3 )"
-    month="$(   echo "${1}" | cut -d' ' -f4 )"
-    weekday="$( echo "${1}" | cut -d' ' -f5 )"
-    command="${2}"
+    pcs_min="$(     echo "${1}" | awk '{print $1}' )"
+    pcs_hour="$(    echo "${1}" | awk '{print $2}' )"
+    pcs_day="$(     echo "${1}" | awk '{print $3}' )"
+    pcs_month="$(   echo "${1}" | awk '{print $4}' )"
+    pcs_weekday="$( echo "${1}" | awk '{print $5}' )"
+    pcs_command="${2}"
+    shift 2
     
-    printf '%-8s%-8s%-8s%-8s%-8s%s' "${min}" "${hour}" "${day}" "${month}" "${weekday}" "${command}"
-}
-
-print_cron_header() {
-    # don't split the '#' from 'min'
-    print_cron_schedule '#_min hour day month weekday' 'command' | tr '_' ' '
+    printf '%-8s%-8s%-8s%-8s%-8s%s\n' "${pcs_min}" "${pcs_hour}" "${pcs_day}" "${pcs_month}" "${pcs_weekday}" "${pcs_command}"
 }
 
 print_crontab() {
     echo   '# crontab generated for kiwi-backup'
     printf '# generation time: '; date
     echo   '#'
-    echo   "$( print_cron_header )"
-    echo   "$( print_cron_schedule "${SCHEDULE_BACKUP}"  "$( print_command backup )" )"
-    echo   "$( print_cron_schedule "${SCHEDULE_CLEANUP}" "$( print_command cleanup )" )"
-    echo   "$( print_cron_schedule "${SCHEDULE_RMFULL}"  "$( print_command rmfull )" )"
-    echo   "$( print_cron_schedule "${SCHEDULE_RMINCR}"  "$( print_command rmincr )" )"
+
+    # don't split the '#' from 'min'
+    print_cron_schedule '#_min hour day month weekday' 'command' | tr '_' ' '
+
+    print_cron_schedule "${SCHEDULE_BACKUP}"  "$( print_command backup )"
+    print_cron_schedule "${SCHEDULE_CLEANUP}" "$( print_command cleanup )"
+    print_cron_schedule "${SCHEDULE_RMFULL}"  "$( print_command rmfull )"
+    print_cron_schedule "${SCHEDULE_RMINCR}"  "$( print_command rmincr )"
 }
 
 ########
 # MAIN #
 ########
 
-if [ "${1}" = '-n' ]; then
-    # dry-run
-    print_crontab
-    exit 0
+
+if [ "${#}" -gt 0 ]; then
+    # run a command
+    case "${1}" in
+        print-crontab)
+            print_crontab
+            ;;
+
+        print-backup|print-cleanup|print-rmfull|print-rmincr)
+            print_command "${1##*-}"
+            ;;
+
+        # execute single command
+        backup|cleanup|rmfull|rmincr)
+            print_command "${1}"
+            cmd="$(print_command "${1}")"
+            ${cmd}
+            ;;
+
+        *)
+            >&2 echo "Unknown command '${1}'."
+            exit 1
+            ;;
+    esac
+
+else
+    # default run: replace crontab, then start crond
+    print_crontab | crontab -
+    crond -fl 8
 fi
 
-# replace crontab, start crond
-print_crontab | crontab -
-crond -fl 8
-exit 0
+exit 0
\ No newline at end of file