learnyoubash

1-hello.bash

#!/usr/bin/env bash

echo "Hello, world!"



#1.touch hello.bash
#2.chmod +x hello.bash
#3. ./hello.bash

10-functions.bash

#!/usr/bin/env bash

greater_even() {
  # return if it's out of range
  [[ $1 -lt $2 ]] || return

  indent="$3"
  if [[ $(( $1 % 2 )) -eq 0 ]]; then
    i=0
    for (( i = 0; i < $indent; i++ )); do
      echo -n ' '
    done
    echo $1

    # update indent only if number is even
    indent=$(( indent + 1 ))
  fi

  greater_even $(( $1 + 1 )) $2 $indent
}

main() {
  echo $FUNCNAME
  greater_even $1 $2 1
}

main $1 $2

11-debugging.bash

#!/usr/bin/env bash 
set -vn
echo $@
touch $@
mkdir ./folder
mv file* ./folder
cd ./folder
ls
set +vn

2-variables.bash

#!/usr/bin/env bash

    echo "User $USER in directory $PWD."

3-parameters.bash

#!/usr/bin/env bash
echo "1: $1"
echo "3: $3"
echo "5: $5"

4-arrays.bash

#!/usr/bin/env bash
output=(I am "${@:2:2}" and "${@:4:1}")

echo "${output[*]}"

5-expansions.bash

#!/usr/bin/env bash
RESULT=$(( ($3 + $2) * $1))

echo project-$RESULT/{src,dest,test}/{index,util}.js

6-lists.bash

#!/usr/bin/env bash
$1 || echo "First parameter is false."

$2 && pwd

$3 && ls || echo "Third parameter is false."

7-if.bash

#!/usr/bin/env bash
if [[ $1 -ge 0 && $1 -lt 12 ]]; then
  echo "Good morning!"
elif [[ $1 -ge 12 && $1 -lt 18 ]]; then
  echo "Good afternoon!"
elif [[ $1 -ge 18 && $1 -lt 24 ]]; then
  echo "Good evening!"
else
  echo "Error!"
fi

8-case.bash

#!/usr/bin/env bash
case "$1" in
  ("jpg"|"jpeg")
    echo 'It is jpeg.'
  ;;
  "png")
    echo 'It is png.'
  ;;
  "gif")
    echo 'It is gif.'
  ;;
  *)
    echo "$1 is not an image!"
esac

9-loops.bash

#!/usr/bin/env bash

i=$1
while [[ $i -lt $2 ]]; do
      [ ! $(( $i % 2 )) -eq 0 ] || echo $i
        i=$(( $i + 1 ))
    done