Shell

$ echo $SHELL
$ ls -l /bin/bash
$ ls -l /bin/zsh

# 运行Bash环境
$ chsh $USER -s /bin/bash

$ su $USER

# 切换到Bash运行环境
$ bash

# 确认命令行中运行的是Bash
$ echo $SHELL

# 确保执行的命令具有可执行权限
$ chmod +x ./shell/helloworld.sh

# 运行脚本
$ ./shell/helloworld.sh

$ bash ./shell/helloworld.sh

$ source ./shell/helloworld.sh

$ . ./shell/helloworld.sh

#!/bin/bash -v
# helloworld.sh

echo "Hello, World"

#!/bin/bash
# helloworld.sh

echo "Hello, World"

$ var_name="wangzhefeng"

$ var_name="wangzhefeng"
$ var_name="zfwang"

$ echo $var_name
$ echo ${var_name}

$ var_name="read only"
$ readonly var_name

$ var_name="wanzhefeng"
$ unset var_name

$ str='this is a string'

$ var="wangzhefeng"
$ str="Hello, I know you are \"$var\"! \n"
$ echo -e $str

$ var1="wangzhefeng"
$ greeting1="hello, "$var1" !"
$ greeting2="hello, ${var1} !"
$ echo $greeting1 $greeting2

$ var2="wangzhefeng"
$ greet1='hello, '$var2' !' # 单引号可以成对出现,作为字符串拼接的使用
$ greet2='hello, ${var2} !' # 单引号中的变量无效
$ echo greet1 greet2

string="abcd"
echo ${#string}

string="wangzhefeng is a man!"
echo ${string:0:11}

# 查找字符串`i`或`o`的位置(哪个字母先出现就计算哪个)
string="wangzhefeng is a man!"
echo `expr index "$string" io`

var="get the length of me"
echo ${var}

# method 1
echo ${#var}

# method 2
expr length "$var"

# method 3
echo $var awk '{printf("%d\n", length($0));}'

# method 4 
 echo -n $var | wc -c

echo $var | tr -cd g | wc -c
echo -n $var | sed -e 's/[^g]//g' | wc -c
echo -n $var | sed -e 's/[^gt]//g' | wc -c

echo $var | wc -w
echo "$var" | tr " " "\n" | grep get | uniq -c 
echo "$var" | tr " " "\n" | grep get | wc -l

:<<EOF 
注释
EOF

:<<'
注释
'

:<<!
注释
!

function func_comment() {
    注释
}

#!/bin/bash
# params.sh

echo "Shell 传递参数!"
echo "第一个参数: $1"
echo "第二个参数: $2"
echo "第三个参数: $3"
echo "传递的参数个数: $#"
echo "传递的参数以一个字符串显示: $*"
echo "传递的参数以多个字符串显示: $@"
echo "Shell使用的当前选项: $-"
echo "Shell最后命令的退出状态: $?"
echo "脚本运行的当前进程ID号: $$"
echo "脚本运行的最后一个进程ID号: $!"

echo "=======\$*的示例========"
for i in "$*"
do 
echo $i
done

echo "=======\$@的示例========"
for i in "$@"
do 
echo $i
done

arrayName=(elem_1 elem_2 ... elem_n)

arrayName=(
    elem_1
    elem_2
    ...
    elem_n
)

arrayName[0]=elem_1
arrayName[1]=elem_2
arrayName[n]=elem_n

${数组名[下标]}

value_n=${arrayName[n]}

echo ${arrayName[@]}

# 取得数组元素的个数
length=${#arrayName[@]}

# or
length=${#arrayName[*]}

# 取得数组单个元素的长度
length_n=${#arrayName[n]}

#!/bin/bash

val=`expr 2 + 2`
echo "两个之和为: $val"

echo "It is a test."

echo It is a test.

echo "\"It is a test\""

echo \"It is a test\"

#!/bin/bash

read name
echo "$name It is a test"

# -e: 开启转义
echo -e "OK! \n"
echo "It is a test"

#!/bin/bash

# -e: 开启转义, \c不换行
echo -e "OK! \c"

echo "It is a test" > myfile

echo '$name\'

echo `date`

printf format-string args

$ echo "wangzhefeng"

$ printf "wangzhefeng\n"

#!/bin/bash

printf "%-10s %-8s %-4s\n" 姓名 性别 体重kg
printf "%-10s %-8s %-4.2s\n" name1 gender1 66.1234
printf "%-10s %-8s %-4.2s\n" name2 gender2 77.2234
printf "%-10s %-8s %-4.2s\n" name3 gender3 88.3234

printf "%d %s\n" 1 "abc"
printf '%d %s\n' 1 "abc"
printf %s abcdef

# 格式只指定了一个参数, 但多出的参数仍然会按照该格式输出, format-string 被重用
printf %s abc def
printf "%s\n" abc def
printf "%s %s %s\n" a b c d e f g h i j k

# 如果没有 arguments, 那么 %s 用NULL代替, %d 用 0 代替
printf "%s and %d \n"

printf "a string, no processing:<%s>\n" "A\nB"
printf "a string, no processing:<%b>\n" "A\nB"

num1=100
num2=100

if test $[num1] -eq $[num2]
then
echo "两个数字相等"
else
echo "两个数字不相等"
if

#!/bin/bash

a=5
b=6

result=$[a+b]
echo "result 是: $result"

str1="wangzhefeng"
str2="tinker"

if test $str1 = $str2
then
echo "两个字符串相等"
else
echo "两个字符串不相等"
fi

cd /bin

if test -e ./bash
then
echo "文件已存在"
else
echo "文件不存在"
fi

cd /bin

if test -e ./notfile -o -e ./bash
then 
echo "至少有一个文件存在"
else
echo "两个文件都不存在"
fi

if [test] condition
then 
command1
command2
...
commandN
fi

if condition then commands fi

if [test] condition
then 
command1
command2
...
commandN
else
commandM
fi

if [test] condition1
then 
command1
elif [test] condition2
then 
command2
else
command3
fi

case value in
mode1)
command1
command2
...
commandN
;;
mode2)
command1
command2
...
commandN
;;
esac

echo "输入1到4之间的数字:"
echo "你输入的数字为:"
read aNum

case $aNum in
1) echo "你选择了 1"
;;
1) echo "你选择了 2"
;;
1) echo "你选择了 3"
;;
1) echo "你选择了 4"
;;
*) echo "你没有输入1到4之间的数字"
;;
esac

for var in item1 item2 ... itemN
do 
command1
command2
...
commandN
done

for var in item1 item2 ... itemN do command1 command2 ... commandN done

for (( ; ;))

while condition
do 
command
done

while :
do
command
done

while true
do
command
done

#!/bin/bash

int=1
while (($int<=5))
do 
echo $int
let "int++"
done

until condition
do 
command
done

#!/bin/bash

a=0
until [!$a -lt 10]
do 
echo $a
a=`expr $a + 1`
done

#!/bin/bash

while :
do
echo -n "输入1到5之间的数字:"
read aNum
case $aNum in
	1|2|3|4|5) echo "你输入的数字是: $aNum"
	;;
	*) echo "你输入的数字不是1到5之间的; "
		break
	;;
esac
done

#!/bin/bash

while :
do 
echo -n "输入1到5之间的数字:"
read aNum
case $aNum in
	1|2|3|4|5) echo "你输入的数字为: $aNum !"
	;;
	*) echo "你输入的数字不是1到5之间的; "
		continue
		echo "游戏结束"
	;;
esac
done

function fun_name(){
action;

return
}

fun_name(){
action;
return
}

fun_name param1, param2, param3, ...

#!/bin/bash
# author: zfwang
# file: demo.sh

demoFun(){
  echo "This is my first Shell function!"
}

# 函数调用
echo "-----函数开始执行-----"
demoFun
echo "-----函数执行完毕-----"

#!/bin/bash
# author: zfwang
# file: funWithReturn.sh

funWithReturn(){
  echo "这个函数会对输入的两个数字进行相加运算..."
  echo "输入第一个数字: "
  read aNum
  echo "输入第二个数字: "
  read anothreNum
  echo "两个数字分别位 $aNum 和 $anotherNum !"
  return ${$aNum+$anotherNum}
}

# 函数调用
funWithReturn
echo "输入的两个数字之和为: $? !"

#!/bin/bash
# author: zfwang
# file: funWithParam.sh

funWithParam(){
echo "第一个参数为 $1 !"
   echo "第二个参数为 $2 !"
   echo "第十个参数为 $10 !"
   echo "第十个参数为 ${10} !"
   echo "第十一个参数为 ${11} !"
   echo "参数总数有 $# 个!"
   echo "作为一个字符串输出所有参数 $* !"
}

# 函数调用
funWithParam 1 2 3 4 5 6 7 8 9 34 73

command > file
command >> file

# 将命令的完整的输出重定向到users文件中
who > users

# 查看users文件中的内容
cat users

# 将输出重定向覆盖users文件中的内容
echo "This is a test command by wangzhefeng" > users

# 查看users文件中的内容
cat users

# 将输出重定向追加到users文件的末尾
echo "This is another test command by wangzhefeng" >> users

command < file

# 统计users文件中的行数(会输出文件名users)
wc -l users

# 统计users文件中的行数(不会输出文件名users)
wc -l < users

# 同时替换输入和输出,执行command,从文件infile读取内容, 然后将输出写入到outfile中
command < infile > outfile

# 将两个delimiter之间的内容(document)作为输入传递给command
command << delimiter
document
delimiter

# 通过wc -l 命令计算Here Document的行数
wc -l << EOF
test line 1
test line 2
test line 3
EOF

#!/bin/bash
# hereDocument.sh

cat << EOF
test line 1
test line 2
EOF

command > /dev/null

# 屏蔽stdout和stderr
command > /dev/null 2>&1

. fileName

# or

source fileName

#!/bin/bash
# file: test1.sh

string1="wangzhefeng in test1.sh"

#!/bin/bash
# file: test2.sh

# 使用`.`来引用test1.sh文件
. ./shell/test1.sh

# 使用`source`来引用test1.sh文件
source ./shell/test1.sh

echo "在test1.sh中的字符串为: $string1"

chmod +x ./shell/test2.sh
./shell/test2.sh

# test

$ if true;then echo "YES"; else echo "NO"; fi
$ if false;then echo "YES"; else echo "NO"; fi

if true && true;then echo "YES"; else echo "NO"; fi
if true && false;then echo "YES"; else echo "NO"; fi
if false && false;then echo "YES"; else echo "NO"; fi
if false && true;then echo "YES"; else echo "NO"; fi

if true || true;then echo "YES"; else echo "NO"; fi
if true || false;then echo "YES"; else echo "NO"; fi
if false || false;then echo "YES"; else echo "NO"; fi
if false || true;then echo "YES"; else echo "NO"; fi

if ! false;then echo "YES"; else echo "NO"; fi
if ! true;then echo "YES"; else echo "NO"; fi

stat file_name
ls -l file_name

ls -l

test

test

$ touch regular_file
$ mkdir directory_file

$ ln regular_file regular_file_hard_link
$ ln -s regular_file regular_file_soft_link

$ mkfifo fifo_pipe
$ mknod hda1_block_dev_file b 3 1
$ mknod null_char_dev_file c 1 3

rm regular_file
rmdir directory_file
rm -r directory_file_not_empty

$ cp regular_file regular_file_copy
$ cp -r directory_file directory_file_copy

# 创建家目录、指定登录 Shell
$ useradd -s /bin/bash -m test
$ groups test

# 创建家目录、指定登录 Shell、加入所属组
$ useradd -s /bin/bash -m -G docker test
$ groups test

# 删除用户以及家目录
$ userdel -r test

# 常常用来修改默认的 Shell
$ usermod -s /bin/bash test

# 把用户加入某个新安装软件所属的组
$ usermod -a -G docker test

# 修改登录用户名并搬到新家
$ usermod -d /home/new_test -m -l new_test test

# 禁用某个账号
$ usermod -L test
$ usermod -expiredate 1 test

$ passwd test

# 让用户 test 无需密码登录(密码为空), 这个很方便某些安全无关紧要的条件下(比如已登录主机中的虚拟机), 可避免每次频繁输入密码
$ passwd -d test

$ passwd test

$ passwd -l user

$ dscl . list /Groups
$ dscl . list /Users

$ sudo dscl . -list /Groups GroupMembership
$ sudo dscl . -append /Groups/groupname GroupMembership username
$ sudo dscl . -delete /Groups/groupname GroupMembership username

$ sudo dscl . -create /Groups/test

$ sudo dscl . -create /Users/redis

$ sudo dscl . -delete /Groups/test

$ sudo dscl . -delete /Users/redis