Bash snippets

check_if_file_exists.sh

#If the file doesn't exist, create the folder and the file in it.

if [ ! -f "$FILE" ]; then
  mkdir -p $FOLDER
  touch "$FOLDER/$FILE"
fi

ifhour_thenmessage.sh

H=$(date +%H)
if (( 5 <= 10#$H && 10#$H < 12 )); then 
    echo "Good morning, $USER."
elif (( 12 <= 10#$H && 10#$H < 17 )); then 
    echo "Good afternoon, $USER."
else
    echo "Good evening, $USER."
fi

options_sample.sh

titles="1) Use Terminal \n2) Upgrade packages \n3) Check mail \n4) Browse the net \n5) Open the IM \n6) Study \n7) Watch a movie \n8) Open TOR \n9) Open Telegram" 

options=("Use Terminal" "Upgrade packages" "Check mail" "Browse the net" "Open Finch IM" "Study" "Watch a movie" "Open TOR" "Open Telegram")
select opt in "${options[@]}"
do
    case $opt in
        "Upgrade packages")
            echo "Ok, wait."
	    sleep 0.5
	    bash ~/Script/update.sh
            clear
	    echo -e $titles
	    ;;
        "Watch a movie")
            bash ~/Script/movie.sh
            clear
	    echo -e $titles
	    ;;
        "Check mail")
            bash ~/Script/mail.sh
	    clear
	    echo -e $titles
	    ;;
	"Use Terminal")
	    echo "Bye!"
	    sleep 0.5
	    gnome-terminal
            exit
            ;;
	"Browse the net")
	    bash ~/Script/elinks.sh
	    clear
	    echo -e $titles
	    ;;
	"Open Finch IM")
	    bash ~/Script/finch.sh
	    clear
	    echo -e $titles
	    ;;
	"Study")
	    bash ~/Script/study.sh
	    clear
	    echo -e $titles
	    ;;
	"Open TOR")
	    bash ~/Script/tor.sh
	    clear
	    echo -e $titles
	    ;;
	"Open Telegram")
	    bash ~/Script/telegram.sh
	    clear
	    echo -e $titles
	    ;;
        *) echo actually this is not an option...please write a number from the list.;;
    esac
done

print_line_7.sh

sed -n '7p' file

progress_bar.sh

```
Use \r to go back to the beginning of the line without writing \n to the terminal.

Write \n when you're done to advance the line.

Use echo -ne to:

    not print \n and
    to recognize escape sequences like \r.

Here's a demo:
```

echo -ne '#####                     (33%)\r'
sleep 1
echo -ne '#############             (66%)\r'
sleep 1
echo -ne '#######################   (100%)\r'
echo -ne '\n'

write_to_file.sh

write_to_file () {

   # initialize local configuration file
   LOCAL_FOLDER="/path/to/dir"
   FILE="file.txt"
   
   # enter a while loop in order to write into the file
   while true; do
      read  -p " " INPUT
      if [ "$INPUT" == ":Q:" ]; then
         # Quit the editor
         echo " All the lines have been written on your FILE"
         return
      else
         # push INPUT to FILE
         echo "$INPUT" >> "$LOCAL_FOLDER/$FILE"
      fi
   done
}