loops.sh

#!/bin/bash

# Make the script to abort if any command fails. Use set +e to change the behaviour and ignore failed command.
set -e

# Uncomment below line to print the commands as it is executed. Useful for debugging. Use set +x to disable debugging.
# set -x

while [[ $# -gt 0 ]]
do
  KEY="$1"
  case $KEY in
      "--conditional-while")
        OPERATION="CONDITIONAL_WHILE"
        shift
        CONDITIONAL_WHILE_COUNT="$1"
        shift
        ;;
      "--print-file")
        OPERATION="PRINT_FILE"
        shift
        FILE_TO_PRINT="$1"
        shift
        ;;
      "--infinite-while-read")
        OPERATION="INFINITE_WHILE_READ"
        shift
        ;;
      "--infinite-while-sleep")
        OPERATION="INFINITE_WHILE_SLEEP"
        shift
        ;;
      "--print-array-for")
        OPERATION="PRINT_ARRAY_FOR"
        shift
        ARRAY_TO_PRINT=( "$@" )
        shift
        ;;
      "--sum-for-loop")
        OPERATION="SUM_FOR_LOOP"
        shift
        ARRAY_TO_SUM=( "$@" )
        shift
        ;;
      "--iterative-for-loop")
        OPERATION="ITERATIVE_FOR_LOOP"
        shift
        ITERATION_COUNT="$1"
        shift
        ;;
      -h|--help)
        OPERATION="HELP"
        shift
        ;;
      *)
        shift
        ;;
  esac
done

function print_usage() 
{
    echo "Usage:"
    echo "bash loops.sh --conditional-while 5"
    echo "bash loops.sh --print-file /tmp/testfile.txt"
    echo "bash loops.sh --infinite-while-read"
    echo "bash loops.sh --infinite-while-sleep"
    echo "bash loops.sh --print-array-for \"value 1\" \"value 2\" \"skip\" \"break\" \"value 3\""
    echo "bash loops.sh --sum-for-loop 3 5 60 1"
    echo "bash loops.sh --iterative-for-loop 6"
}

# Display usage of the script
if [[ "$DISPLAY_HELP" == "yes" ]]
then
    print_usage
    exit 0
fi

function conditional_while()
{
    x=1
    while [[ $x -le $1 ]]
    do
        echo "Welcome $x times"
        x=$(( $x + 1 ))
    done
}

function print_file()
{
    if [[ ! ( -f $1 ) && ! ( -r $1 ) ]]
    then
        echo "File $1 doesn't exist or doesn't have read permission"
        exit 1
    fi
    cat "$1" | while read line
    do 
        echo "$line"
    done
}

function infinite_while_read()
{
    while :
    do
        read -p "Enter two numbers ( -1 to quit, 0 to skip ) : " a b
        if [[ $a -eq -1 ]]
        then
            break
        elif [[ $a == 0 ]]
        then
            continue
        fi
        echo "$a + $b" | bc
    done
}

function infinite_while_sleep()
{
    while :
    do
        echo "Sleeping for 1.5 seconds, Time before sleep"
        date
        sleep 1.5
        echo "Woke up after 1.5 seconds, Time after wake up"
        date
        echo "Press Ctrl+C to exit"
        date
    done
}

function print_array_for()
{
    for i in "$@"
    do 
        if [[ $i == "break" ]]
        then
            break
        elif [[ $i == "skip" ]]
        then
            continue
        else
            echo "Hello $i"
        fi        
    done
}

function sum_array_for_loop()
{
    SUM=0
    for i in "$@"
    do 
        SUM=$(echo "$SUM + $i" | bc)
    done
    echo $SUM
}

function iterative_for_loop()
{
    for (( c=1; c<=$1; c=$c+1 ))
    do  
        echo "Welcome $c times"
    done
}

case "$OPERATION" in
    "CONDITIONAL_WHILE")
        conditional_while $CONDITIONAL_WHILE_COUNT
        ;;
    "PRINT_FILE")
        print_file "$FILE_TO_PRINT"
        ;;
    "INFINITE_WHILE_READ")
        infinite_while_read
        ;;
    "INFINITE_WHILE_SLEEP")
        infinite_while_sleep
        ;;
    "PRINT_ARRAY_FOR")
        print_array_for "${ARRAY_TO_PRINT[@]}"
        ;;
    "SUM_FOR_LOOP")
        sum_array_for_loop "${ARRAY_TO_SUM[@]}"
        ;;
    "ITERATIVE_FOR_LOOP")
        iterative_for_loop $ITERATION_COUNT
        ;;
    "HELP")
        print_usage
        ;;
    *)
        echo "Unknown operation" >&2
        print_usage
        exit 1
        ;;
esac