shell script 编程入门

参考《linux shell scripting cookbook》

控制台输出

结构化输出

#!/bin/bash

#Filename: printf.sh

printf "%-5s %-10s %-4s\n" No Name Mark

printf "%-5s %-10s %-4.2f\n" 1 Sarath 80.3456

printf "%-5s %-10s %-4.2f\n" 2 James 90.9989

printf "%-5s %-10s %-4.2f\n" 3 Jeff 77.564

结果：

No    Name       Mark

1     Sarath     80.35

2     James      91.00

3     Jeff       77.56

输出彩色文字

echo -e "\e[1;33m This is red text \e[0m"

\e[1;31m 是设置颜色为红色 \e[0m 是重置颜色 , 这样就不会影响后面的输出

前景色:

reset = 0, black = 30, red = 31,

green = 32, yellow = 33, blue = 34, magenta = 35, cyan = 36, and white = 37

背景色:

reset = 0, black = 40, red = 41, green = 42, yellow = 43, blue = 44,

magenta = 45, cyan = 46, and white=47

字符替换

cat c1.sh

eqeqeqweqe eqeweqwewqe eqwewqeqweq   wqeqweqwewqe

eqwewqe;wqewqewqewqqdfewfr;erqrqrqwrwq;

空格或者; 替换为换行符

cat c1.sh | tr ' |;' '\n'

eqeqeqweqe

eqeweqwewqe

eqwewqeqweq

wqeqweqwewqe

eqwewqe

wqewqewqewqqdfewfr

erqrqrqwrwq

字符串的长度

root@kali:~# content='hello world'

root@kali:~# echo ${#content}

11

识别当前的shell

root@kali:~# echo $SHELL

/bin/bash

root@kali:~# echo $0

bash

检测当前脚本执行用户是不是超级用户

#!/bin/bash

if [ $UID -ne 0 ]; then

 echo Non root user. Please run as root.

else

 echo Root user

fi

root@kali:~/shell# ./c1.sh

Root user

kali@kali:/root/shell$ ./c1.sh

Non root user. Please run as root.

文件操作

0: stdin (standard input)

1: stdout (standard output)

2: stderr (standard error)

正常的输出重定向到文件

root@kali:~# echo aa > stdout.txt

root@kali:~# cat stdout.txt

aa

异常的输出重定向到文件

这种写不进去

root@kali:~# ls + > stderr.txt

ls: cannot access '+': No such file or directory

root@kali:~# cat stderr.txt

root@kali:~#

这样可以

root@kali:~# ls + 2> stderr.txt

root@kali:~# cat stderr.txt

ls: cannot access '+': No such file or directory

也可以

root@kali:~# ls + &>> stderr.txt

root@kali:~# cat stderr.txt

ls: cannot access '+': No such file or directory

ls: cannot access '+': No such file or directory

输入重定向

root@kali:~/shell# cat domains.txt

www.baidu.com

root@kali:~/shell# exec 3< domains.txt

root@kali:~/shell# cat <&3

www.baidu.com

root@kali:~/shell#

输出重定向

root@kali:~/shell# exec 4> output.txt

root@kali:~/shell#

root@kali:~/shell# cat output.txt

root@kali:~/shell# echo haha >&4

root@kali:~/shell# cat output.txt

haha

root@kali:~/shell#

数组

root@kali:~/shell# array_var=(a b c d e f)

root@kali:~/shell#

root@kali:~/shell# echo ${array_var[*]}

a b c d e f

root@kali:~/shell# echo ${array_var[2]}

c

root@kali:~/shell# echo ${#array_var[*]}

6

root@kali:~/shell# echo ${array_var[@]}

a b c d e f

root@kali:~/shell#

别名

del 替换 rm 防止误操作

alias rm='echo "rm is disabled, use del instead."'

alias del='/bin/rm'

如果要在其他窗口生效,添加到~/.bashrc

编写高质量的 shell 脚本

cat 输出

root@kali:~/shell# cat in.txt

iinnniniii

root@kali:~/shell# ls -l |cat - in.txt

total 12

-rwxr-xr-x 1 root root 110 Oct 17 11:34 c1.sh

-rw-r--r-- 1 root root  11 Oct 17 15:59 in.txt

-rw-r--r-- 1 root root  28 Oct 17 15:55 out.txt

iinnniniii

find 正则查找

root@kali:~/shell# find . -regex ".*\(\.txt\|\.sh\)$"

./c1.sh

./in.txt

./out.txt

文件的类型:

时间类型,单位(天)

Access time (-atime): 访问时间

Modification time (-mtime): 修改时间(内容)

Change time (-ctime): 修改时间(元数据,权限什么的)

单位(分钟)

-amin (access time)

-mmin (modification time)

-cmin (change time)

查找类型为f,最近访问在7天之前的

find . -type f -atime +7

文件大小

b: 512 byte blocks

c: Bytes

w: Two-byte words

k: Kilobyte (1024 bytes)

M: Megabyte (1024 kilobytes)

G: Gigabyte (1024 megabytes)

find . -type f -atime +7 -size +10M

查找并删除

find . -name out.txt -delete

xargs 改变输出的排版

root@kali:~/shell# cat in.txt

iinnniniii

sds

dsds

dsd

dsds

ds

dsd

1 2

3 4 5 678 99 0 0 -fg  gd gdfg dfh 

dsfdsgdsg  ghgf g f

root@kali:~/shell# cat in.txt | xargs

iinnniniii sds dsds dsd dsds ds dsd 1 2 3 4 5 678 99 0 0 -fg gd gdfg dfh dsfdsgdsg ghgf g f

root@kali:~/shell# cat in.txt | xargs -n 3

iinnniniii sds dsds

dsd dsds ds

dsd 1 2

3 4 5

678 99 0

0 -fg gd

gdfg dfh dsfdsgdsg

ghgf g f

root@kali:~/shell# echo "splitXsplitXsplitXsplit" | xargs -d X

split split split split

前面的输出作为后面的输入

find . -type f -name "*.txt"  -print | xargs rm -f

tr 转换

大小写

root@kali:~/shell# echo "HELLO WHO IS THIS" | tr 'A-Z' 'a-z'

hello who is this

替换和删除

root@kali:~/shell# echo "HELLO WHO IS THIS 123" | tr 'A-Za-z'   ' '

                  123

root@kali:~/shell# echo "HELLO WHO IS THIS 123" | tr -d 'A-Za-z'

    123

root@kali:~/shell# echo "HELLO WHO IS THIS 123" | tr -d 'A-Za-z '

123

互补性删除(下面就是删除非 0-9 的字符 )

root@kali:~/shell# echo "HELLO WHO IS THIS 123" | tr -d -c '0-9\n'

123

压缩空格

root@kali:~/shell# echo "HELLO   WHO IS  THIS   123" | tr -d ' '

HELLOWHOISTHIS123

root@kali:~/shell#

root@kali:~/shell#

root@kali:~/shell# echo "HELLO   WHO IS  THIS   123" | tr -s ' '

HELLO WHO IS THIS 123

累加

root@kali:~/shell# cat sum.txt

1

2

3

4

5

root@kali:~/shell# cat sum.txt | echo $[ $(tr '\n' '+' ) 0 ]

15

文件加密解密

base64 sum.txt > sum.txt.b64

root@kali:~/shell# cat sum.txt.b64

MQoyCjMKNAo1Cgo=

root@kali:~/shell# base64 -d sum.txt.b64

1

2

3

4

5

文件操作

排序

root@kali:~/shell# cat a.txt

apple

orange

gold

silver

steel

iron

root@kali:~/shell# sort a.txt

apple

gold

iron

orange

silver

steel

找到公共的内容

首先要把内容排序

root@kali:~/shell# source a.txt -o  a.txt

root@kali:~/shell# sort b.txt -o  b.txt

root@kali:~/shell# comm a.txt b.txt 

apple

	    carrot

	    cookies

		            gold

iron

		            orange

silver

steel

只显示公共部分

root@kali:~/shell# comm a.txt b.txt -1 -2

gold

orange

不显示公共部分

root@kali:~/shell# comm a.txt b.txt -3

apple

	    carrot

	    cookies

iron

silver

steel

联合执行指令

结束所有的Windows进程

root@kali:~# ps -aux |grep windows |awk '{print $2}' | xargs kill -9