backup.sh

#!/bin/bash

# This checks if the number of arguments is correct
# If the number of arguments is incorrect ( $# != 2) print error message and exit
if [[ $# != 2 ]]
then
  echo "backup.sh target_directory_name destination_directory_name"
  exit
fi

# This checks if argument 1 and argument 2 are valid directory paths
if [[ ! -d $1 ]] || [[ ! -d $2 ]]
then
  echo "Invalid directory path provided"
  exit
fi

# [TASK 1]
targetDirectory="$1"
destinationDirectory="$2"

# [TASK 2]
echo "First argument: $1"
echo "Second argument: $2"

# [TASK 3]
currentTS=$(date +%s)

# [TASK 4]
backupFileName="backup_${currentTS}.tar.gz"


# We're going to:
  # 1: Go into the target directory
  # 2: Create the backup file
  # 3: Move the backup file to the destination directory

# To make things easier, we will define some useful variables...

# [TASK 5]
origAbsPath=$(pwd)

# [TASK 6]
cd "$destinationDirectory"
destDirAbsPath=$(pwd)


# [TASK 7]
cd  "$origAbsPath"
cd "$targetDirectory"

# [TASK 8]
yesterdayTS=$(($currentTS - 24 * 60 * 60))
#find /path/to/directory -type f -newermt "$(date -d @$yesterdayTS '+%Y-%m-%d %H:%M:%S')"


declare -a toBackup

for file in * # [TASK 9]
do
  # [TASK 10]
  file_last_modified_date=$(date -r "$file" +%s)
  if [[ $file_last_modified_date -gt $yesterdayTS ]]
  then
    # [TASK 11]
    toBackup+=($file)
  fi
done

# [TASK 12]
if [ ${#toBackup[@]} -gt 0 ];
then
  tar -czvf $backupFileName ${toBackup[@]}
# [TASK 13]
mv "$backupFileName" "$destDirAbsPath"
echo "Backup moved to: $destDirAbsPath"
else
   echo "No files were modified in the last 24 hours."
fi