shell_sequencer/sequencer.sh

#!/bin/bash

# Automatic sequence control script

#
## Start of customization part

function step_1 {
  echo -e "Eins"
  cat .nofile
  saveReturn $?
}

function step_2 {
  echo -e "Zwei"
  endReturn
  echo zwo
}

function step_3 {
  echo -e "Drei"
  echo drei
}

function step_10 {
  echo -e "Zehn"
  echo zehn 
}

function step_11 {
  echo -e"Elf"
  echo elf
}

help() {
  echo "Usage: ${0##*/} [Options] [Step Number(s)]" 
  echo
  echo "  [Options]"
  echo "    -q : Don't ask for permission to execute next step"
  echo "         If called without starting step number only this help is shown"
  echo 
  echo "  [Step Number(s) 1-255]"
  echo "      Single step number  : starting point of process"
  echo "    Multiple step numbers : execute only given steps"
  echo "                            execute only one step with using special step 0"
  echo "                            ( e.g. only execute step 4: $0 4 0 )" 
  echo "  Step Documentation"
  echo "    1: Step with failure and saveReturn"
  echo "    2: Step with endReturn at the beginning"
  echo "    3: Regular step without return check (last step when starting with 1 or 2)"
  echo
  echo "   10: Regular step without return check (staring point for separate sequence)"
  echo "   11: Regular step without return check (last step of sequence starting with 10)"
}

#
## Start of generic script part
## (do not change)

QUIET=0
ERNO=0

# endCheckEmpty [VariableName] [DESCRIPTION]
#    DESCRIPTION : Optional text for error
function endCheckEmpty() {
   local errorText=$1
   eval 'local ref=$'$1
   
   if [ ! -z "$2" ] ; then
	errorText=$2
   fi
   if [ -z $ref ] ; then
	echo -e "[Error] $errorText must not be empty.\nAborting installation."
	exit 666
  fi 
}

function saveReturn() {
  if [ $1 -ne 0 ] ; then
    ERNO=$1
  fi
}

# endReturn [-f]
#   -f : force exit with $ERNO without user input
function endReturn() {
  if [[ ( $ERNO -ne 0 && $QUIET -ne 0 ) || ( $ERNO -ne 0 && ! -z $1 && $1 == "-f" ) ]] ; then
    echo
    echo -e "[Error] Return value $ERNO detected.\nAborting installation."
    exit $ERNO
  fi
  if [ $ERNO -ne 0 ] ; then
    echo
    echo "[Error] Return value $ERNO detected."
    read -p "End installation: y(default)/n? " answer
    case $answer in
      [nN])
         echo
         echo Continuing installation...
         ;;
      *)
         echo
         echo Installation aborted
         exit $ERNO; 
         ;;
    esac
  fi
}

# execute [-q] <Step Number>
#    -q: don't stop and don't report step functions which cannot be found 
# execute given step_<Step Number> function
function execute() {
  local NOTFOUND=0
  local NOREPORT=0
  
  if [ $1 == "-q" ] ; then
    NOREPORT=1
    shift
  fi

  # check if step function exists
  declare -F step_$1 &>>/dev/null || NOTFOUND=1
  if [ $NOTFOUND -eq 1 ] && [ $NOREPORT -ne 1 ] ; then
    echo "Step $1 not found" 
    exit 1;
  fi

  # don't execute step functions which are not available
  if [ $NOTFOUND -eq 1 ] ; then
    return $NOTFOUND
  fi 

  echo -en "\n[STEP $1] "
  if [ $QUIET -ne 1 ] ; then
    read -p "Start: y/n(default)? " answer
    case $answer in
      [yY])
         step_$1 $1
         ;;
      *)
         echo Aborting installation at step $1
         exit 1; 
         ;;
    esac
  else
    step_$1 $1
  fi
}

# continous <Starting Step Number>
# (max 255)
# execute installation continously from given starting step
function continous() {
  for ((i=$1; i<=255; i++)); do
    execute -q $i
    local res=$?
    if [ $res -ne 0 ] ; then
      break;
    fi
  done
}

# selection <Step Number List (separated by space)>
# execute given step list
# e.g.: selection -q 1 4 12
function selection() {
  for i in $@ ; do
  # stop on step 0 
  if [ $i -eq 0 ] ; then
    break
  else 
    execute $i
  fi
  done
}

main() {
  # detect if option quiet is available
  if [ ! -z "$1" ] && [ $1 == "-q" ] ; then
    QUIET=1
    shift
  fi

  # display help  
  if [ -z "$1" ] ; then
    help
    START=1
    if [ $QUIET -eq 1 ] ; then
      exit 1;
    fi
  else
    START=$1
  fi

  # check if more than one step is given and select execution mode
  if [ ! -z $2 ] ; then
    selection $@  
  else
    continous $START
  fi

  echo
  echo "${0##*/} finished"
}

main "$@"
exit 0;