Advanced Bash script, and use the classic case
Introduction: In linux, Bash script is very basic knowledge, you may feel a script on a very big, like a small series had just started to learn the same, the feeling will write the script is great God. Although the script is very complex brain burn, but when we skilled master usage and techniques of them, and then more practice, will one day become a handy script great God. Script in a production role, presumably small series I do not say, we all know, the script written by 6, can save a lot of complex operations, reduce their operating pressure. Well, ado, then, is the use of Bash scripts show.
First, conditions are selected, it is determined
1, conditions are selected if
(1) Usage format
if
the determination condition. 1
; the then
The condition is true branch code
elif
judgment conditions 2
; the then
The condition is true branch code
elif determination condition 3; then
The condition is true branch code
else
The above conditions are false branch code
be
To judge by the conditions, the first case of "true" condition, the implementation of its branches, then the whole end if.
(2) Classic Case:
① determine the age
#!/bin/bash
read -p "Please input your age: " age
if [[ $age =~ [^0-9] ]] ;then
echo "please input a int"
exit 10
elif [ $age -ge 150 ];then
echo "your age is wrong"
exit 20
elif [ $age -gt 18 ];then
echo "good good work,day day up"
else
echo "good good study,day day up"
fi
Analysis: Enter the age, comprising first determining whether the input character other than numbers, there is, on the error; no, continue to determine whether less than 150, is greater than 18.
② judge scores
#!/bin/bash
read -p "Please input your score: " score
if [[ $score =~ [^0-9] ]] ;then
echo "please input a int"
exit 10
elif [ $score -gt 100 ];then
echo "Your score is wrong"
exit 20
elif [ $score -ge 85 ];then
echo "Your score is very good"
elif [ $score -ge 60 ];then
echo "Your score is soso"
else
echo "You are loser"
fi
Analysis: Enter the results, determines whether the input contains the first character other than numbers, there is, on the error; no, continue to determine whether or not greater than 100, is greater than 85, it is greater than 60.
2, conditional case
(1) Usage format
case $name
in;
PART1)
cmd
;;
PART2)
cmd
;;
*)
cmd
;;
esac
Note: case supports glob-style wildcards:
*: Any character of any length
?: Any single character
[]: Any single character within the specified range
a | b: a certain b
(2) Case:
Determine yes or no
#!/bin/bash
read -p "Please input yes or no: " anw
case $anw in
[yY][eE][sS]|[yY])
echo yes
;;
[nN][oO]|[nN])
echo no
;;
*)
echo false
;;
esac
Analysis: Enter yes or no, answer Y / y, yes Yes for the various combinations of case; Answer N / n, No for the various combinations of case no.
Two, four cycles
1、for
(1) Usage format
For ①
name in
the list
; do
Loop
done
②
for (( exp1; exp2; exp3 )) ;do
cmd
done
exp1 performed only once, while the equivalent embedded for years in
③ enforcement mechanisms: in order to list the elements assigned to "variable name"; each assignment after the execution of a loop body; until the elements in the list is exhausted, the end of the cycle
Representation of the list, glob wildcards can, as {1..10}, * sh; may be a variable reference, such as:. `Seq 1 $ name`
(2) Case
① determined (1 + 2 + ... + n) sum
sum=0
read -p "Please input a positive integer: " num
if [[ $num =~ [^0-9] ]] ;then
echo "input error"
elif [[ $num -eq 0 ]] ;then
echo "input error"
else
for i in `seq 1 $num` ;do
sum=$[$sum+$i]
done
echo $sum
fi
unset zhi
Analysis: sum initial value 0, enter a number, comprising first determining whether the input character other than numbers, there is, on the error; not determined whether 0, for entering the loop is not 0, i ranging from 1 to input the number of cycles of each sum = sum + i, the end of the cycle, the sum of the last output value.
② determined (1 + 2 + ... + 100) sum
for (( i=1,num=0;i<=100;i++ ));do
[ $[i%2] -eq 1 ] && let sum+=i
done
echo sum=$sum
Analysis: i = 1, num = 0; if i <= 100, enter the circulation, if the modulo i ÷ 2 = 1, then the sum = sum + i, i = i + 1.
2、while
(1) Usage format
while
loop control condition
; do
cycle
done
Loop control conditions; before entering the loop, do first judge; every time to make a judgment before looping again; the condition is "true", then perform a loop; until the condition test status to "false" terminates the loop
(2) Special usage (each line traversing file):
while read line; do initialization control variables
Loop
done
< /PATH/FROM/SOMEFILE
或
cat /PATH/FROM/SOMEFILE
| while read line; do
Loop
done
Sequentially reads each line / PATH / FROM / SOMEFILE file, and will be assigned to the variable line row
(3) Case:
① Within all positive odd number of 100 and
sum=0
i=1
while [ $i -le 100 ] ;do
if [ $[$i%2] -ne 0 ];then
let sum+=i
let i++
else
let i++
fi
done
echo "sum is $sum"
Analysis: sum initial value 0, i is the initial value of 1; Please enter a number, comprising first determining whether the input character other than numbers, there is, on the error; no when i <100, into the circulation, is determined i ÷ modulo 2 if not 0, an odd number is not 0, sum = sum + i, i + 1, is 0, i + 1; end of the loop, the final output value of the sum.
3, an until loop
(1) Usage
unitl
loop condition
; do
cycle
done
Entry conditions: the loop condition is true; the exit condition: the loop condition is false; just
and while the opposite
, it is not commonly used by while on the line.
(2) Case
Monitoring xiaoming user, login to kill
until pgrep -u xiaoming &> /dev/null ;do
sleep 0.5
done
pkill -9 -u xiaoming
Analysis: scanning every 0.5 seconds, until you find xiaoming user logs on, kill the process, exit the script for monitoring user login.
4, the SELECT loop with the menu
(1) Usage
select variable
in list
do
Loop command
done
① select cycle primarily used to create a menu, the menu items shown in numerical order of the standard error will be displayed, and displays the PS3 prompt and waits for user input
② user enter a number in the menu list, perform the corresponding command
③ The user input is stored in the built-in variable REPLY
④ select an infinite loop, so keep in mind that exit the loop with the break command, or by using exit command to terminate the script. You can also exit the loop press ctrl + c
⑤ select and often used in conjunction with case
⑥ and for similar loop can be omitted in list, this time using the position quantity
(2) Case:
Build menu, and display the selected price
PS3="Please choose the menu: "
select menu in mifan huimian jiaozi babaozhou quit
do
case $REPLY in
1|4)
echo "the price is 15"
;;
2|3)
echo "the price is 20"
;;
5)
break
;;
*)
echo "no the option"
esac
done
Analysis: PS3 prompt is select, automatically generated menu, select 5break exit the loop.
Third, in some usage cycle
1, loop control statements
(1) grammar
Continue
[N]: early termination of
the current round of layer N
cycles, directly into the next round is determined; innermost layer a first layer
BREAK
[N]: ahead of the end
of the N layer
cycle, the first layer is the innermost
例：while CONDTITON1; do
CMD1
if CONDITION2; then
continue / break
be
CMD2
done
(2) Case:
① requirements (1 + 3 + ... + 49 + ... + 53 + 100) and
#!/bin/bash
sum=0
for i in {1..100} ;do
[ $i -eq 51 ] && continue
[ $[$i%2] -eq 1 ] && { let sum+=i;let i++; }
done
echo sum=$sum
Analysis: do cycle 2 + ... + 1 + 100, when i = 51, skip this cycle, but the entire cycle continues, the result is: sum = 2449
② requirements (1 + 3 + ... + 49) and
#!/bin/bash
sum=0
for i in {1..100} ;do
[ $i -eq 51 ] && break
[ $[$i%2] -eq 1 ] && { let sum+=i;let i++; }
done
echo sum=$sum
Analysis: do cycle 2 + ... + 1 + 100, when 51 i =, out of the entire cycle, the result is: sum = 625
2, shift command control loop
(1) the role of
The list of parameters for a specified number of list to the left, the far left of the parameters can be removed from the list, its parameters back into the cycle continues
(2) Case:
① create multiple user specified
#!/binbash
if [ $# -eq 0 ] ;then
echo "Please input a arg(eg:`basename $0` arg1)"
exit 1
else
while [ -n "$1" ];do
useradd $1 &> /dev/null
shift
done
fi
Analysis: If no input parameters (total parameter to 0), an error and exit; on the contrary, enter the circulation; if the first argument is not empty characters, create a user with the name of the first argument, and removes the first a parameter, followed by the parameters to the left as the first parameter, not until the first argument, quit.
② printing characters right triangle
#!/binbash
while (( $# > 0 ))
do
echo "$*"
shift
done
3, the return value of the result
true
always return a successful result
: null command ,什么也不干，返回成功结果
false 永远返回错误结果
创建无限循环
while true ;do
循环体
done
4、循环中可并行执行，使脚本运行更快
（1）用法
for name in 列表 ;do
{
循环体
}&
done
wait
（2）实例：
搜寻自己指定ip（子网掩码为24的）的网段中，UP的ip地址
read -p "Please input network (eg:192.168.0.0): " net
echo $net |egrep -o "\<(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\>"
[ $? -eq 0 ] || ( echo "input error";exit 10 )
IP=`echo $net |egrep -o "^([0-9]{1,3}\.){3}"`
for i in {1..254};do
{
ping -c 1 -w 1 $IP$i &> /dev/null && \
echo "$IP$i is up"
}&
done
wait
分析：请输入一个IP地址例192.168.37.234，如果格式不是0.0.0.0 则报错退出；正确则进入循环，IP变量的值为192.168.37. i的范围为1-254，并行ping 192.168.37.1-154，ping通就输出此IP为UP。直到循环结束。
四、信号捕获trap
1、用法格式
trap ' 触发指令' 信号，自定义进程收到系统发出的指定信号后，将执行触发指令，而不会执行原操作
trap '' 信号，忽略信号的操作
trap '-' 信号，恢复原信号的操作
trap -p，列出自定义信号操作
信号可以3种表达方法：信号的数字2、全名SIGINT、缩写INT
2、常用信号
1) SIGHUP: 无须关闭进程而让其重读配置文件
2) SIGINT: 中止正在运行的进程；相当于Ctrl+c
3) SIGQUIT: 相当于ctrl+\
9) SIGKILL: 强制杀死正在运行的进程
15) SIGTERM ：终止正在运行的进程（默认为15）
18) SIGCONT ：继续运行
19) SIGSTOP ：后台休眠
9 信号，强制杀死，捕获不住
3、案例
① 打印0-9，ctrl+c不能终止
#!/bin/bash
trap 'echo press ctrl+c' 2
for ((i=0;i<10;i++));do
sleep 1
echo $i
done
分析：i=0，当i<10，每休眠1秒，i+1，捕获2信号，并执行echo press ctrl+c
② 打印0-3，ctrl+c不能终止，3之后恢复，能终止
#!/bin/bash
trap '' 2
trap -p
for ((i=0;i<3;i++));do
sleep 1
echo $i
done
trap '-' SIGINT
for ((i=3;i<10;i++));do
sleep 1
echo $i
done
分析：i=0，当i<3，每休眠1秒，i+1，捕获2信号；i>3时，解除捕获2信号。
五、脚本小知识（持续更新）
1、生成随机字符 cat /dev/urandom
生成8个随机大小写字母或数字 cat /dev/urandom |tr -dc [:alnum:] |head -c 8
2、生成随机数 echo $RANDOM
确定范围 echo $[RANDOM%7] 随机7个数（0-6）
echo $[$[RANDOM%7]+31] 随机7个数（31-37）
3、echo打印颜色字
echo -e "\033[31malong\033[0m" 显示红色along
echo -e "\033[1;31malong\033[0m" 高亮显示红色along
echo -e "\033[41malong\033[0m" 显示背景色为红色的along
echo -e "\033[31;5malong\033[0m" 显示闪烁的红色along
color=$[$[RANDOM%7]+31]
echo -ne "\033[1;${color};5m*\033[0m" 显示闪烁的随机色along
六、分享几个有意思的小脚本
1、9x9乘法表
#!/bin/bash
for a in {1..9};do
for b in `seq 1 $a`;do
let c=$a*$b ;echo -e "${a}x${b}=$c\t\c"
done
echo
done
2、彩色等腰三角形
#!/bin/bash
read -p "Please input a num: " num
if [[ $num =~ [^0-9] ]];then
echo "input error"
else
for i in `seq 1 $num` ;do
xing=$[2*$i-1]
for j in `seq 1 $[$num-$i]`;do
echo -ne " "
done
for k in `seq 1 $xing`;do
color=$[$[RANDOM%7]+31]
echo -ne "\033[1;${color};5m*\033[0m"
done
echo
done
fi
3、国际象棋棋盘
#!/bin/bash
red="\033[1;41m \033[0m"
yellow="\033[1;43m \033[0m"
for i in {1..8};do
if [ $[i%2] -eq 0 ];then
for i in {1..4};do
echo -e -n "$red$yellow";
done
echo
else
for i in {1..4};do
echo -e -n "$yellow$red";
done
echo
fi
done
前言：在linux中，Bash脚本是很基础的知识，大家可能一听脚本感觉很高大上，像小编当初刚开始学一样，感觉会写脚本的都是大神。虽然复杂的脚本是很烧脑，但是，当我们熟练的掌握了其中的用法与技巧，再多加练习，总有一天也会成为得心应手的脚本大神。脚本在生产中的作用，想必小编我不说，大家也都知道，脚本写的6，可以省下很多复杂的操作，减轻自己的工作压力。好了，废话不多说，接下来，就是Bash脚本的用法展示。
一、条件选择、判断
1、条件选择if
（1）用法格式
if 判断条件 1
; then
条件为真的分支代码
elif 判断条件 2
; then
条件为真的分支代码
elif 判断条件 3 ; then
条件为真的分支代码
else
以上条件都为假的分支代码
fi
逐条件进行判断，第一次遇为“真”条件时，执行其分支，而后结束整个if。
（2）经典案例：
① 判断年纪
#!/bin/bash
read -p "Please input your age: " age
if [[ $age =~ [^0-9] ]] ;then
echo "please input a int"
exit 10
elif [ $age -ge 150 ];then
echo "your age is wrong"
exit 20
elif [ $age -gt 18 ];then
echo "good good work,day day up"
else
echo "good good study,day day up"
fi
分析：请输入年纪，先判断输入的是否含有除数字以外的字符，有，就报错；没有，继续判断是否小于150，是否大于18。
② 判断分数
#!/bin/bash
read -p "Please input your score: " score
if [[ $score =~ [^0-9] ]] ;then
echo "please input a int"
exit 10
elif [ $score -gt 100 ];then
echo "Your score is wrong"
exit 20
elif [ $score -ge 85 ];then
echo "Your score is very good"
elif [ $score -ge 60 ];then
echo "Your score is soso"
else
echo "You are loser"
fi
分析：请输入成绩，先判断输入的是否含有除数字以外的字符，有，就报错；没有，继续判断是否大于100，是否大于85，是否大于60。
2、条件判断 case
（1）用法格式
case $name
in;
PART1)
cmd
;;
PART2)
cmd
;;
*)
cmd
;;
esac
注意：case 支持glob 风格的通配符：
*: 任意长度任意字符
?: 任意单个字符
[] ：指定范围内的任意单个字符
a|b: a 或b
（2）案例：
判断yes or no
#!/bin/bash
read -p "Please input yes or no: " anw
case $anw in
[yY][eE][sS]|[yY])
echo yes
;;
[nN][oO]|[nN])
echo no
;;
*)
echo false
;;
esac
分析：请输入yes or no，回答Y/y、yes各种大小写组合为yes；回答N/n、No各种大小写组合为no。
二、四个循环
1、for
（1）用法格式
① for
name in 列表
;do
循环体
done
②
for (( exp1; exp2; exp3 )) ;do
cmd
done
exp1只执行一次，相当于在for里嵌了while
③ 执行机制：依次将列表中的元素赋值给“变量名”; 每次赋值后即执行一次循环体; 直到列表中的元素耗尽，循环结束
列表的表示方法，可以glob 通配符，如{1..10} 、*.sh ；也可以变量引用，如： `seq 1 $name`
（2）案例
① 求出（1+2+...+n）的总和
sum=0
read -p "Please input a positive integer: " num
if [[ $num =~ [^0-9] ]] ;then
echo "input error"
elif [[ $num -eq 0 ]] ;then
echo "input error"
else
for i in `seq 1 $num` ;do
sum=$[$sum+$i]
done
echo $sum
fi
unset zhi
分析：sum初始值为0，请输入一个数，先判断输入的是否含有除数字以外的字符，有，就报错；没有判断是否为0，不为0进入for循环，i的范围为1~输入的数，每次的循环为sum=sum+i，循环结束，最后输出sum的值。
② 求出（1+2+...+100）的总和
for (( i=1,num=0;i<=100;i++ ));do
[ $[i%2] -eq 1 ] && let sum+=i
done
echo sum=$sum
分析：i=1,num=0；当i<=100，进入循环，若i÷2取余=1，则sum=sum+i，i=i+1。
2、while
（1）用法格式
while 循环控制条件
;do
循环
done
循环控制条件；进入循环之前，先做一次判断；每一次循环之后会再次做判断；条件为“true” ，则执行一次循环；直到条件测试状态为“false” 终止循环
（2）特殊用法（遍历文件的每一行）：
while read line; do控制变量初始化
循环体
done
< /PATH/FROM/SOMEFILE
或
cat /PATH/FROM/SOMEFILE
| while read line; do
循环体
done
依次读取/PATH/FROM/SOMEFILE文件中的每一行，且将行赋值给变量line
（3）案例：
① 100以内所有正奇数之和
sum=0
i=1
while [ $i -le 100 ] ;do
if [ $[$i%2] -ne 0 ];then
let sum+=i
let i++
else
let i++
fi
done
echo "sum is $sum"
分析：sum初始值为0，i的初始值为1；请输入一个数，先判断输入的是否含有除数字以外的字符，有，就报错；没有当i<100时，进入循环，判断 i÷2取余 是否不为0，不为0时为奇数，sum=sum+i，i+1，为0，i+1；循环结束，最后输出sum的值。
3、until 循环
（1）用法
unitl 循环条件
;do
循环
done
进入条件：循环条件为true ；退出条件：循环条件为false；刚好
和while相反，所以不常用，用while就行。
（2）案例
监控xiaoming用户，登录就杀死
until pgrep -u xiaoming &> /dev/null ;do
sleep 0.5
done
pkill -9 -u xiaoming
分析：每隔0.5秒扫描，直到发现xiaoming用户登录，杀死这个进程，退出脚本，用于监控用户登录。
4、select 循环与菜单
（1）用法
select variable
in list
do
循环体命令
done
① select 循环主要用于创建菜单，按数字顺序排列的示菜单项将显示在标准错误上，并显示PS3 提示符，等待用户输入
② 用户输入菜单列表中的某个数字，执行相应的命令
③ 用户输入被保存在内置变量 REPLY 中
④ select 是个无限循环，因此要记住用 break 命令退出循环，或用 exit 按 命令终止脚本。也可以按 ctrl+c退出循环
⑤ select 和 经常和 case 联合使用
⑥ 与for循环类似，可以省略 in list， 此时使用位置参量
（2）案例：
生成菜单，并显示选中的价钱
PS3="Please choose the menu: "
select menu in mifan huimian jiaozi babaozhou quit
do
case $REPLY in
1|4)
echo "the price is 15"
;;
2|3)
echo "the price is 20"
;;
5)
break
;;
*)
echo "no the option"
esac
done
分析：PS3是select的提示符，自动生成菜单，选择5break退出循环。
三、循环里的一些用法
1、循环控制语句
（1）语法
continue [N]：提前结束
第N层的本轮循环，而直接进入下一轮判断；最内层为第1层
break [N]：提前结束
第N层循环，最内侧为第1层
例：while CONDTITON1; do
CMD1
if CONDITION2; then
continue / break
fi
CMD2
done
（2）案例：
① 求（1+3+...+49+53+...+100）的和
#!/bin/bash
sum=0
for i in {1..100} ;do
[ $i -eq 51 ] && continue
[ $[$i%2] -eq 1 ] && { let sum+=i;let i++; }
done
echo sum=$sum
分析：做1+2+...+100的循环，当i=51时，跳过这次循环，但是继续整个循环，结果为：sum=2449
② 求（1+3+...+49）的和
#!/bin/bash
sum=0
for i in {1..100} ;do
[ $i -eq 51 ] && break
[ $[$i%2] -eq 1 ] && { let sum+=i;let i++; }
done
echo sum=$sum
分析：做1+2+...+100的循环，当i=51时，跳出整个循环，结果为：sum=625
2、循环控制shift命令
（1）作用
用于将参数列表list左移指定次数，最左端的那个参数就从列表中删除，其后边的参数继续进入循环
（2）案例：
① 创建指定的多个用户
#!/binbash
if [ $# -eq 0 ] ;then
echo "Please input a arg(eg:`basename $0` arg1)"
exit 1
else
while [ -n "$1" ];do
useradd $1 &> /dev/null
shift
done
fi
分析：如果没有输入参数（参数的总数为0），提示错误并退出；反之，进入循环；若第一个参数不为空字符，则创建以第一个参数为名的用户，并移除第一个参数，将紧跟的参数左移作为第一个参数，直到没有第一个参数，退出。
② 打印直角三角形的字符
#!/binbash
while (( $# > 0 ))
do
echo "$*"
shift
done
3、返回值结果
true 永远返回成功结果
: null command ,什么也不干，返回成功结果
false 永远返回错误结果
创建无限循环
while true ;do
循环体
done
4、循环中可并行执行，使脚本运行更快
（1）用法
for name in 列表 ;do
{
循环体
}&
done
wait
（2）实例：
搜寻自己指定ip（子网掩码为24的）的网段中，UP的ip地址
read -p "Please input network (eg:192.168.0.0): " net
echo $net |egrep -o "\<(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\>"
[ $? -eq 0 ] || ( echo "input error";exit 10 )
IP=`echo $net |egrep -o "^([0-9]{1,3}\.){3}"`
for i in {1..254};do
{
ping -c 1 -w 1 $IP$i &> /dev/null && \
echo "$IP$i is up"
}&
done
wait
分析：请输入一个IP地址例192.168.37.234，如果格式不是0.0.0.0 则报错退出；正确则进入循环，IP变量的值为192.168.37. i的范围为1-254，并行ping 192.168.37.1-154，ping通就输出此IP为UP。直到循环结束。
四、信号捕获trap
1、用法格式
trap ' 触发指令' 信号，自定义进程收到系统发出的指定信号后，将执行触发指令，而不会执行原操作
trap '' 信号，忽略信号的操作
trap '-' 信号，恢复原信号的操作
trap -p，列出自定义信号操作
信号可以3种表达方法：信号的数字2、全名SIGINT、缩写INT
2、常用信号
1) SIGHUP: 无须关闭进程而让其重读配置文件
2) SIGINT: 中止正在运行的进程；相当于Ctrl+c
3) SIGQUIT: 相当于ctrl+\
9) SIGKILL: 强制杀死正在运行的进程
15) SIGTERM ：终止正在运行的进程（默认为15）
18) SIGCONT ：继续运行
19) SIGSTOP ：后台休眠
9 信号，强制杀死，捕获不住
3、案例
① 打印0-9，ctrl+c不能终止
#!/bin/bash
trap 'echo press ctrl+c' 2
for ((i=0;i<10;i++));do
sleep 1
echo $i
done
分析：i=0，当i<10，每休眠1秒，i+1，捕获2信号，并执行echo press ctrl+c
② 打印0-3，ctrl+c不能终止，3之后恢复，能终止
#!/bin/bash
trap '' 2
trap -p
for ((i=0;i<3;i++));do
sleep 1
echo $i
done
trap '-' SIGINT
for ((i=3;i<10;i++));do
sleep 1
echo $i
done
分析：i=0，当i<3，每休眠1秒，i+1，捕获2信号；i>3时，解除捕获2信号。
五、脚本小知识（持续更新）
1、生成随机字符 cat /dev/urandom
生成8个随机大小写字母或数字 cat /dev/urandom |tr -dc [:alnum:] |head -c 8
2、生成随机数 echo $RANDOM
确定范围 echo $[RANDOM%7] 随机7个数（0-6）
echo $[$[RANDOM%7]+31] 随机7个数（31-37）
3、echo打印颜色字
echo -e "\033[31malong\033[0m" 显示红色along
echo -e "\033[1;31malong\033[0m" 高亮显示红色along
echo -e "\033[41malong\033[0m" 显示背景色为红色的along
echo -e "\033[31;5malong\033[0m" 显示闪烁的红色along
color=$[$[RANDOM%7]+31]
echo -ne "\033[1;${color};5m*\033[0m" 显示闪烁的随机色along
六、分享几个有意思的小脚本
1、9x9乘法表
#!/bin/bash
for a in {1..9};do
for b in `seq 1 $a`;do
let c=$a*$b ;echo -e "${a}x${b}=$c\t\c"
done
echo
done
2、彩色等腰三角形
#!/bin/bash
read -p "Please input a num: " num
if [[ $num =~ [^0-9] ]];then
echo "input error"
else
for i in `seq 1 $num` ;do
xing=$[2*$i-1]
for j in `seq 1 $[$num-$i]`;do
echo -ne " "
done
for k in `seq 1 $xing`;do
color=$[$[RANDOM%7]+31]
echo -ne "\033[1;${color};5m*\033[0m"
done
echo
done
fi
3、国际象棋棋盘
#!/bin/bash
red="\033[1;41m \033[0m"
yellow="\033[1;43m \033[0m"
for i in {1..8};do
if [ $[i%2] -eq 0 ];then
for i in {1..4};do
echo -e -n "$red$yellow";
done
echo
else
for i in {1..4};do
echo -e -n "$yellow$red";
done
echo
fi
done