test.sh

#!/bin/bash

# 賦值
pathName='hello world'
# echo 是列印值，印出變數 pathName 內容 demo.sh
echo ${pathName}

# $$ 目前 process PID
#  ${0} 為檔名

# 刪除值
unset pathName
# 空值
echo ${pathName}

# 運算式
result=`expr 10 + 2`

# 12
echo "Result: $result"

# if else 
# == 為等於
# != 為不等於
# -gt （greater than 縮寫）
# -lt （less than 縮寫）
# -ge （greater equal 縮寫)
# -le（less equal 縮寫

value1=20
value2=30
value3=30

if [ $value1 -gt $value2 ]; then
   echo "value1 is greater than value2"
elif [ $value1 == $value3 ]; then
   echo "value1 is equal to value3"
else
   echo "other result"
fi

# switch
language='Java'

case $language in
    Java*) echo "是 Java！"
            ;;
    Python*) echo "是 Python！"
            ;;
    C*)     echo "是 C！"
            ;;
    *)      echo "沒 match 到！"
esac

# for
# 可加上 break, continue
for loop in 1 2 3; do
    echo "number: $loop"
done

# while
counter=0
while [ $counter -le 5 ]; do
    counter=`expr $counter + 1`
    echo $counter
done

echo "======="

# until
# 從 0 印出數字直到 10
counter=0
until [ $counter -gt 10 ]; do
   echo $counter
   counter=`expr $counter + 1`
done

echo "======="

# function
function echoHello() {
    # hello world, rock!!
    # ${0} 為檔名
    echo "${0} hello ${1}, ${2}!!"
}

echoHello 'world' 'rock'

# 執行指令, 以下兩種方式皆可
test=$(pwd)
test=`pwd`
echo $test

DIRS=(\
backend/testdata/temp \
slideworker/static)

for i in "${DIRS[@]}"; do
    echo $i
done

# 將多行寫到檔案內
test_file="test_file.txt"
cat <<EOF > $test_file
line1
line2

EOF