bash variables plus operator All In One

bash variables plus operator All In One

Errors

missing pass params

#!/usr/bin/env bash

# echo  emoji ^-v-^
# echo " emoji ^-v-^"

# = 两边不可以有空格
# arg1 = $1
# OK， no space
arg1=$1
arg2=$2
sum=$(($arg1 + $arg2))

echo $arg1
echo $arg2
# -e 换行
echo -e "\n"
echo $sum

#!/bin/bash

# OK， no space
arg1=$1
arg2=$2
sum=$(($arg1 + $arg2))

echo $arg1
echo $arg2
# -e 换行
echo -e "\n"
echo $sum

Solutions

just need pass args OR 参数可以为空

#!/usr/bin/env bash

# echo  emoji ^-v-^
# echo " emoji ^-v-^"

# = 两边不可以有空格
# arg1 = $1
# OK， no space
arg1=$1
arg2=$2
#  , 参数可以为空
sum=$((arg1 + arg2))
# OR
# ,  参数不可以为空
# sum=$(($arg1 + $arg2))

echo $arg1
echo $arg2
# -e 换行
echo -e "\n"
echo $sum

# DEMO
# ./sum.sh 1 2

#!/bin/bash

# OK， no space
arg1=$1
arg2=$2
#  , 参数可以为空
sum=$((arg1 + arg2))
# OR
# ,  参数不可以为空
# sum=$(($arg1 + $arg2))

echo $arg1
echo $arg2
# -e 换行
echo -e "\n"
echo $sum

# DEMO
# ./add.sh 1 2

bash add operator

#!/bin/bash

#!/usr/bin/env bash

arg1=$1
arg2=$2

#
num=$(($arg1 + $arg2))

#
str=$((arg1 + arg2))

echo "num: \$arg1 + \$arg2 = $num"
# -e 换行
echo -e "\n"
echo "str: arg1 + arg2 = $str"

# DEMO
# ./num.sh 1 2

# num: $arg1 + $arg2 = 3

# str: arg1 + arg2 = 3

#!/usr/bin/env bash

arg1=$1
arg2=$2

#
num=$(($arg1 + $arg2))

#
str=$((arg1 + arg2))

echo "num: \$arg1 + \$arg2 = $num"
# -e 换行
echo -e "\n"
echo "str: arg1 + arg2 = $str"

# DEMO
# ./str.sh 1 2

# num: $arg1 + $arg2 = 3

# str: arg1 + arg2 = 3

https://github.com/xgqfrms/linux/blob/master/zsh/num.sh

https://github.com/xgqfrms/linux/blob/master/zsh/str.sh

refs

https://www.imooc.com/notepad/2582fb

https://www.imooc.com/u/1066707/notepad/336

https://www.howtogeek.com/442332/how-to-work-with-variables-in-bash/

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