Bash语法讲解

1. 首个字符必须为字母（a-z，A-Z）
2. 中间不能有空格，可以使用下划线_
3. 不能使用标点符号
4. 不能使用bash里的关键字（help查看保留关键字）

如: a=1 b=“hello”

readonly a=“nochange”

names="I like python"
names=(hello world python)
 
if [[ "${names[@]}"  =~ "python" ]]; then
    echo '字符串存在'
fi

array=()
array+=("first")
echo ${array[@]}

IPS=(192.168.12.11 192.168.12.12 192.168.12.13 192.168.12.14)
 
key=$(( $RANDOM % ${#IPS[*]} ))
value=${IPS[$key]}
 
echo $key $value

redisService=([1020]=marco [1021]=shanks [1022]=yupoo [1023]=updns [1024]=robin)
echo ${#redisService[*]}
 
for port in ${!redisService[*]};do
   name=${redisService[$port]}
   echo $name, $port
done

如： if while for

if…then…fi
if…then…else..fi
if…then…elif…then…else…fi
case…in…esac

score="90"
 
if [ $score -ge 90 ];then
        echo "A"
elif [ $score -ge 80 ];then
        echo "B"
elif [ $score -ge 70 ];then
        echo "C"
else
        echo "D"
fi

case "$1" in
        start)
                echo "start server...";;
        stop)
                echo "stop server...";;
        *)
                echo "unknown action";;
esac

for …in …do…done
while …do…done
while read…do…done

total=0
 
#for((i=0;i<=100;i++));do
for i in `seq 1 100`;do
        ((total+=i))
done
 
echo $total

total=0
i=0
while [ $i -le 100 ];do
        total=$[$total+$i]
        ((i++))
done
 
echo $total

#!/bin/sh
verbose=''
 
while getopts 'af:v' flag; do
    case "${flag}" in
        a) echo "aaa";;
        f) files="${OPTARG}" ;;
        v) verbose='1.0.0' ;;
        *) echo "Unexpected option ${flag}" ;;
    esac
done
[ ! -z $files ] && echo $files
[ ! -z $verbose ] && echo $verbose

注意：如果字符后跟冒号(例如f:)，则该选项预期具有参数。

用法示例：./script -v -a -b -f filename

#!/bin/sh
while read -r LINE;do
       echo $LINE
done < test.txt

MENU="TV Movie Game Sport"
echo "which do you like?"
select list in $MENU Quit;do
        [ $list = "Quit" ] && echo "ByeBye" && break;
        echo "Oh,you like $list !"
done

#!/bin/sh
read -t15 -n5 -p "请输入你的编号（<=5位数）" userid
read -t5  -n5 -s -p "请输入你的密码（限时5秒）"  userpass
 
printf "\n%10s : %10s\n" $userid $userpass

#!/bin/bash 
read -n1 -p "Do you want to continue [Y/N]? " answer 
case $answer in 
Y|y) 
    echo "fine ,continue";; 
N|n) 
    echo "ok,good bye";; 
*) 
    echo "error choice";; 
esac
exit 0

#!/bin/sh
BONDING="bond0|eth0@eth1@eth2@eth3@eth4@eth5|0|118.123.118.134|255.255.255.224|118.123.118.129|1500"
xx=$IFS;IFS="|";read -r nick devs mode ip mask gw mtu <<<"$BONDING";IFS=$xx

#!/bin/bash
printf "%-10s %-8s %-4s\n" 姓名 性别 体重kg  
printf "%-10s %-8s %-4.2f\n" 郭靖 男 66.1234 
printf "%-10s %-8s %-4.2f\n" 杨过 男 48.6543 
printf "%-10s %-8s %-4.2f\n" 郭芙 女 47.9876

ctrl-a 跳转到行首 
ctrl-e 跳转到行尾 
ctrl-b 往后移动字符
ctrl-f  往前移动字符
ctrl-w 回退剪切一个单词 
ctrl-u 剪切至行首  
ctrl-k 剪切至行尾 
ctrl-y 粘贴剪切板内容 
ctrl-r 反向搜索历史命令 

下表是linux终端所支持的基本颜色的代码：

除了基本的色彩代码，linux还支持一些额外的样式控制代码，如下表所示：

演示代码

#/bin/bash
for STYLE in 0 1 4 5 7 8; do
    for FG in 30 31 32 33 34 35 36 37; do
        for BG in 40 41 42 43 44 45 46 47; do
            CTRL="\033[${STYLE};${FG};${BG}m"
            echo -en "${CTRL}"
            echo -n "${STYLE};${FG};${BG}"
            echo -en "\033[0m"
        done
        echo
    done
    echo
done
# Reset
 
echo -e "\033[0m"