Variables

mission_name=mars-mission
rocket_status=$(rocket-status $mission_name)
echo "Status of launch: ${rocket_status}_state"

Command Line Arguments

• mission_name=$1

Input

• read mission_name
• read -p "Enter mission name:" mission_name

Arithmetic Operations

• expr $A + $B
• expr $A - $B
• expr $A / $B
• expr $A \* $B
• echo $(( A + B ))
• echo $(( A - B ))
• echo $(( A / B ))
• echo $(( A * B ))
• echo $(( ++A ))
• echo $(( --A ))
• echo $(( A++ ))
• echo $(( A-- ))

Conditional Logic

if

mission_name=mars-mission
rocket_status=$(rocket-status $mission_name)

if [ $rocket_status = "failed" ]
then
	rocket-debug $mission_name
elif [ $rocket_status = "failed" ]
then
	echo "This is successful"
else
	echo "The state is not failed or successed"
fi

for

for mission in $(cat mission-names.txt)
do
	create-and-launch-rocket $mission
done

for mission in 1 2 3 4 5 6 
do
	create-and-launch-rocket mission-$mission
done

for mission in {1..100}
do
	create-and-launch-rocket mission-$mission
done

while

while [ $rocket_status = "launching" ]
do
	sleep 2
    rocket_status=$(rocket-status $mission_name)
done

case statements

echo "1. shutdown"
echo "2. Restart"
echo "3. Exit Menu"
read -p "Enter your choice: " choice

case $choice in
	1) shutdown now ;;
    2) shutdown -r now ;;
    3) break ;;
    #) continue ;;
esac

Conditional Operators

• [ "abc" = "abc" ]
• [ "abc" != "abc" ]
• [ 5 -eq 5 ] - equal
• [ 5 -ne 5 ] - not equal
• [ 6 -gt 5 ] - greater than
• [ 5 -lt 6 ] - less than

• [[ "abcd" = "*bc*" ]]
• [[ "abc" = ab[cd] ]]
• [[ "abc" > "bcd" ]]

• [[ A -gt 4 && A -lt 10 ]]
• [[ A -gt 4 || A -lt 10 ]]

• [ -e <file> ] - 파일 존재 여부
• [ -d <file-or-directory> ] - 파일 또는 디렉토리 존재 여부
• [ -s <file> ] - 파일 크기가 0보다 큰지 여부
• [ -x <file> ] - 파일 실행 가능 여부
• [ -z <file> ] - 빈 파일 체크

ETC

shebang

#!/bin/bash

exit codes

echo $?

function

function launch-rocket() {
  mission_name=$1
  mkdir $mission_name
  rocket-add $mission_name

  rocket-start-power $mission_name
  rocket-internal-power $mission_name
  rocket-start-sequence $mission_name
  rocket-start-engine $mission_name
  rocket-lift-off $mission_name
  rocket_status=$(rocket-status $mission_name)
  w
  hile [ $rocket_status == "launching" ]
  do
    sleep 2
    rocket_status=$(rocket-status $mission_name)
  done
  
  if [$rocket_status = "failed" ]
  then
    rocket-debug $mission_name
    exit 1
  fi
}

launch-rocket saturn-mission
LUNAR_STATUS_CODE=$?