Shell Scripting常用範例說明

建議開頭

#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
export LANG="en_US.UTF-8"

註解

#user comment

定義變數與列印變數

VAR="hello world"
echo $VAR

printf "\33[1;31m"
printf "Color Version: $VAR"
printf "\33[0m\n"

正常結束

exit 0

if-else判斷式

if [ "$INPUT" == "Yes" ]; then
  echo "result is Yes"
elif [ "$INPUT" == "No" ]; then
  echo "result is No"
else
  echo "wrong input"
fi

讀取argument

if [ ! -z "$1" ]; then
  ARGS=$1
fi
echo $ARGS

檢查執行者身份

whoami_ret="$(whoami)"
if [ "$whoami_ret" != "root" ]; then
  echo "This script must be run as root"
  exit
fi

使用者輸入

read -p "Please input (Y/N), default is N:" ANSWER
if [ "$ANSWER" == "Y" -o "$ANSWER" == "y" ]; then
  echo "result is Yes"
fi

執行指令的結果

pyOpenSSL_ret="$(rpm -q python-openssl | grep install | wc -l)"
if [ "$pyOpenSSL_ret" == "1" ]; then
  echo "python-openssl is not installed, please install python-openssl"
  exit
fi  

類似traverse陣列

SERVER_LIST=(192.168.0.1 192.168.0.2 192.168.0.3)
for IP in ${SERVER_LIST[@]}
do
  echo "IP address: $IP"
done

Switch case

case $CAR in
  AUDI | audi)
    echo "audi"
  ;;
  VOLVO | volvo)
    echo "volvo"
  ;;
  BENZ | benz)
    echo "benz"
  ;;
  *) 
    echo "wrong role type"
    exit
  ;;
esac

Loop

until [ "$ANSWER" == "yes" ]
do
  read -p "Please input \"yes\":" ANSWER
done

i=0
while [ "$i" != "10" ]
do
  i=$(($i+1))
  echo $i
done

for CAR in AUDI VOLVO BENZ
do
 echo ${CAR}
done

for i in $(seq 1 10)
do
  echo ${i}
done

for (( i=1; i<=10; i=i+1 ))
do
  echo $i
done

等候某個事件發生

FILE_EXISTED=0;
while [ $FILE_EXISTED -ne "1" ]; 
do
  if [ -z "/root/test_file" ];then
    FILE_EXISTED=1
  fi
  sleep 1;
done

Function

function PRINT_FUNCTION(){
  echo "args is $1"
}

PRINT_FUNCTION "first_args"

參考 http://tldp.org/LDP/abs/html/ http://linux.vbird.org/linux_basic/0340bashshell-scripts.php