Shell編程示例

把我以前爲別人寫的給你吧  不過我沒有註釋
說以下大致的功能
一  每隔30分鐘將cpu 內存 使用的情況寫入日誌
#!/bin/bash

LOGPATH="."

info() {
echo ""  >> $LOGPATH/log.txt
echo ""  >> $LOGPATH/log.txt
echo -n "============" >> $LOGPATH/log.txt
date >> $LOGPATH/log.txt

#cpu
mpstat -A >> $LOGPATH/log.txt
echo "" >>  $LOGPATH/log.txt

#memory
free -l  >> $LOGPATH/log.txt
echo "" >>  $LOGPATH/log.txt

#disk
df -h >> $LOGPATH/log.txt
echo "" >>  $LOGPATH/log.txt

# network
# nload 
}

echo "" > $LOGPATH/log.txt
while [ 2 -gt 1 ]; do
 info;
 sleep 1800;
done

二  做一個菜單 包誇4項功能 輸入數字 選擇相應的功能
第1項 顯示指定的信息（如用戶/shell等） 
第2項 任意輸入兩個數，選擇加減乘除 做一運算 給出結果
第3項 輸入一串以0結尾的大寫字字母串 給出其中最小的一個字母（按ascii碼）
第4項  確認並退出
#!/bin/bash

PS3='Input option(1-4):'
stack="Display Cacluate Sort Quit"
select choice in $stack; do
    if [ "$choice" = "Display" ]; then
       read -p "Input you want to display[name/path/shell/cal]"  info
       if [ "$info" = "name" ]; then
  echo "$USER"
       elif [ "$info" = "path" ]; then
  echo "$HOME"
       elif [ "$info" = "shell" ]; then
  echo "$SHELL"
       elif [ "$info" = "cal" ]; then
  cal 2011
       fi
    elif [ "$choice" = "Cacluate" ]; then
 read -p "Input one number: " num1
        read -p "Input the other number: " num2
 read -p "Input method[A/S/M/D]: "  mod
 case $mod in
     'A' ) echo "$num1 + $num2 is $((num1+num2))";;
     'S' ) echo "$num1 - $num2 is $((num1-num2))";;
     'M' ) echo "$num1 * $num2 is $((num1*num2))";;
     'D' ) echo "$num1 / $num2 is $((num1/num2))";;
             *  ) echo "wrong method";;
        esac
    elif [ "$choice" = "Sort" ]; then
 read -p "Input an string with 0 ended:" str
        res=`echo $str | awk -F"0" '{print $1}'`
 echo $res | awk -F "" '{ a=$1; for(i=2;i<NF;i++) if( $i < a) a=$i; print a}'
    elif [ "$choice" = "Quit" ]; then
 read -s -n1 -p "Do you really want to quit?(Y)"
 if [ "$REPLY" = "Y" ];then
     exit 0;
        fi
    else
 echo "Invalid selection, Please input number."
    fi
done