bash-101.sh

#!/usr/bin/env bash

LINE=$(printf '%0.s=' $(seq 1 ${COLUMNS:-$(tput cols)}))
BLD="\e[1m"   #Bold
BLK="\e[5m"   #Blink
YLW="\e[33m"  #Yellow Text
GRN="\e[32m"  #Green Text
RED="\e[31m"  #Red Text

YLWBG="\e[43m"      #Yellow Background
GRNBG="\e[42m"      #Green Background
REDBG="\e[41m"      #Red Background

E="\e[0m"     #Erase all attributes


echo -e $RED$LINE$E
echo -e $BLD Some Examples: $E '\n'

echo -e Some texts are better $BLD bold $E '\n'
echo -e $RED$LINE$E '\n'
echo -e Some are better when they are $BLK blinking $E ! '\n'

echo -e $RED$LINE$E '\n'
echo -e "Some are even better in $GRNBG background $E or $GRN foreground $E colors :) \n"

echo -e $RED$LINE$E
echo -e "Here's how you parse arguments\n"

# A POSIX variable
OPTIND=1         # Reset in case getopts has been used previously in the shell.

# Initialize our own variables:
output_file=""
verbose=0

while getopts "h?vf:" opt; do
    case "$opt" in
    h|\?)
        echo -e "args: -v for verbosity, -f to define the file etc"
        exit 0
        ;;
    v)  verbose=1
        ;;
    f)  output_file=$OPTARG
        ;;
    esac
done

shift $((OPTIND-1))

[ "${1:-}" = "--" ] && shift

echo -e "verbose=$verbose, output_file='$output_file', Leftovers: $@"


echo -e "\n$GRN simple FOR loop $E"
echo -e $RED$LINE$E

for OUTPUT in $(printenv)
do
	echo $OUTPUT
done

echo -e "\n$GRN simple WHILE loop $E"
echo -e $RED$LINE$E

x=1
while [ $x -le 5 ]
do
  echo -e "Welcome $x times"
  x=$(( $x + 1 ))
done

echo -e "\n$GRN simple IF statement $E"
echo -e $RED$LINE$E

if date +%s
then
   echo -e "I've successfully printed out the date!"
else
   echo -e "I made a mistake in the command"
fi