Shell Programming and Scripting

#!/bin/bash
#This is mycat. Similar to cat.
#For detailed information use path/to/mycat.sh -h option

arguments=$#

if [[ "$arguments" -eq 0 ]] #in case of standard input
then
while [[ "$input" != "EndInput" ]]
do
read input
echo $input
done
else
case $1 in #take action according to specified option
  	"-n")
		nl < $2 #number lines
  		;;

  	"-E")
   	sed 's/$/$/' < $2 #redirect file and add $ at the end of each line
  		;;

        "-A"
        sed 's/   /^I/g' < $2 > newfile.list
        sed l < newfile.list
                ;;

        "-T"
        sed 's/   /^I/g'
                ;;

  	"-h")
		echo
		echo "mycat. Concatenates and/or displays files from standard input to standard output for free."
		echo
		echo "SYNOPSIS"
		echo "   /path/to/mycat.sh [OPTION] [FILE]"
		echo
		echo "OPTIONS"
		echo "   -n                         number all output lines"
		echo "   -E                         displays $ at the end of each line"
		echo "   -h                         to display help"
		echo "   -T                         display tabs as ^I"
                echo "   -A                         show -all"
                echo
		echo "EndInput to end"
		;;

  *) #case with more than one file.
  while [ "$arguments" -ne 0 ]
  do
  line_number=1
  last_line=$(tail -1 < $1) 
  while [[ "$last_line" != "$line_to_display" ]] #go through the whole file
  do
  last_line=$(tail -1 < $1)
  line_to_display=$(head -$line_number < $1 | tail -1) #display current line
  echo "$line_to_display"
  ((line_number++))
  done
  shift #go to next file and decrease $# with 1
  arguments=$# 
  done;;
 esac
fi
exit 0

#/bin/bash
# A program to emulate the "rm" command in UNIX.


# INITIALIZE VARIABLES
NO_ARGS=0
FLAG_R=""
FLAG_F_I=""
FLAG_V=""
TRASH=$HOME/deleted

# FUNCTIONS

function errors() {
if [ "$#" -eq  "$NO_ARGS" ] ; then
      echo "rm: too few arguments"
      echo "Try \`rm --help' for more information."
      exit 0
elif [[  ! -f "$1"  && ! -d "$1"   ]] ; then
      echo "rm: cannot remove $ARG : no such file or directory"
      exit 0
elif [[ -d $ARG  &&  "$FLAG_R" = ""  ]] ; then
      echo "rm: \`$ARG' is a directory"
      exit 0
else
     checkExisting $1
fi
}


function checkExisting (){
if [ -d $TRASH/$1 ]; then

     find "$TRASH/$1" -type f -exec shred -fu {} \; 2>/dev/null
     find "$TRASH/$1" -type d -exec rmdir -p  {} \; 2>/dev/null
     directoryDelete $1
else
     directoryDelete $1

fi

}

function directoryDelete () {
if [[ -d "$1"  &&  "$FLAG_R" == "R" && "$FLAG_F_I" == "i" ]]; then
echo -n "rm: descend into directory \`$1'?"
     read A
     if [[ "$A" = [Yy] ]] ; then
echo  "removing all entries of directory \`$1'?"

for FILE in $1/*
do
       if [ -d $FILE ] ; then
       directoryDelete $FILE
   else
       writePro $FILE
fi
done
     echo -n "rm: remove directory \`$1'?"
     read A
     if [[ "$A" = [Yy] ]] ; then
     mv  $1 $TRASH 2>/dev/null
echo "rm: removing directory itself: \`$1'"
fi
fi
else
    writePro $1
fi
}

function writePro () {
if ! [ -w  "$1" ] ; then
echo -n "rm: remove write-protected file \`$*'?"
     read A
     if [[ "$A" = [Yy] ]] ; then
     delete $1
     fi
else
     delete $1
fi

}

function delete() {
if [ "$FLAG_F_I" = "i" ] &&  [ -w  "$1" ] ; then
   interactive $1
elif [ "$FLAG_F_I" = "f"  ] ; then
   force $1
elif [ "$FLAG_R" = "R"  ] ; then
   remove $1
else
   remove $1
fi

}

function force () {

mv -f $1 $TRASH 2>/dev/null
verbose $1
}


function remove () {
mv  $1 $TRASH 2>/dev/null
verbose $1
}

function interactive () {
echo -n "rm: remove $1 ?"
     read A
     if [[ "$A" = [Yy] ]] ; then
     remove $1
     else
     exit 0
fi
}
function verbose () {
if [ "$FLAG_V" = "v" ] ; then
echo "removing \`$1'"
fi
}


# PARSE OPTIONS WITH GETOPTS

while getopts :rRfvi o
do    case $o in
           r|R) FLAG_R=R
             ;;
             f) FLAG_F_I=f
             ;;
             v) FLAG_V=v
             ;;
             i) FLAG_F_I=i
             ;;
             *) echo "rm: invalid option -$1"
                echo "try \`rm --help' for more information"
                exit 0
      esac
done
shift `expr $OPTIND - 1`

# START OF FLOW

if ! [ -d "$HOME/deleted" ] ; then
     mkdir $HOME/delete
elif  [ $# -eq $NO_ARGS ] ; then
errors
else
   for ARG in $@
   do
   errors $ARG
   done
fi