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等號(hào)兩邊不能有空格

變量名不能以數(shù)字開頭

值有空格要用單引號(hào)或雙引號(hào)括起來；雙引號(hào)里面的特殊符號(hào)，比如$是有特殊含義的，如果用單引號(hào)就只是表示一個(gè)符號(hào)，失去了特殊的含義

#!/bin/bash

#read接收鍵盤輸入信息姓名，寫入變量name

read -p? "please your name : " name

echo $name

#read接收鍵盤輸入信息密碼，寫入變量passwd

read -p? "please you passwd : " passwd

echo -e "\r"

echo $passwd

#read接收鍵盤輸入信息性別，寫入變量sex

read -n 1 -p "please input youn sex [M/F]: " sex

#if多分支判斷是男還是女

if [ $sex == "M" ];then

? ? ? ? echo -e "\r"

? ? ? ? echo "$sex"

elif? [ $sex == "F" ];then

? ? ? ? echo? -e "\r"

? ? ? ? echo "$sex"

else

? ? ? ? echo -e "\r"

? ? ? ? echo "please input right sex [M/F]."

fi

#!/bin/bash

#num1和num2兩個(gè)變量賦值位置參數(shù)變量$1、$2

num1=$1

num2=$2

#變量sum求和的值是num1加num2

sum=$(($num1+$num2))

#打印輸出變量sum的值

echo $sum

bash?預(yù)定義變量

$?

$$

$!

#!/usr/bin/env?bash????
arg1=$1????
arg2=$2????
#??????
num=$(($arg1?+?$arg2))????
#??????
str=$((arg1?+?arg2))????
echo?"num:?\$arg1?+?\$arg2?=?$num"????
#?-e?換行????
echo?-e?"\n"????
echo?"str:?arg1?+?arg2?=?$str"????
#?DEMO????
#?./str.sh?1?2????
#?num:?$arg1?+?$arg2?=?3????
#?str:?arg1?+?arg2?=?3

zsh bug

https://stackoverflow.com/questions/18428374/commands-not-found-on-zsh

for loop

for i in $*

? do

? ? ?echo "參數(shù) i" $i?

? done

#!/usr/bin/env bash

echo ? emoji ^-v-^

# -e 換行

echo -e "\n"

arg1=$1

arg2=$2

arg3=$3

arg4=$4

arg5=$5

arg6=$6

arg7=$7

arg8=$8

arg9=$9

# >= 10, $n => ${n} ?

arg10=${10}

arg11=${11}

arg12=${12}

# arg10=$10

# arg11=$11

# arg12=$12

echo $arg1

echo $arg2

echo $arg3

echo $arg4

echo $arg5

echo $arg6

echo $arg7

echo $arg8

echo $arg9

echo $arg10

echo $arg11

echo $arg12

# ? ?, 參數(shù)可以為空

all=$((arg1 + arg2 + arg3 + arg4 + arg5 + arg6 + arg7 + arg8 + arg9 + arg10 + arg11 + arg12))

# -e 換行

echo -e "\n"

echo $all

# DEMO

# ./dollar-args.sh 1 2 3 4 5 6 7 8 9 10 11 12

# 55 + 23 = 78

# const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];

# arr.reduce((acc, item) => acc += item, 0);

$n, $0, $1~$9, ${10}~${n}

$* , 參數(shù)整體

$@， 參數(shù)列表

$#，參數(shù)個(gè)數(shù)

export PATH=/usr/local/nginx/sbin/:$PATH (網(wǎng)上查找的添加進(jìn)環(huán)境變量的命令) 注意 自定義的路徑在環(huán)境變量$PATH之前 并且用分號(hào)＂：＂分隔

變量疊加的應(yīng)用

PATH="$PATH":/root/sh

PATH : 系統(tǒng)搜索命令的路徑

常用環(huán)境變量

Linux中所有的命令都是小寫