建设电子商务网站流程,做建材网站,网站地域分站怎么做,京东官网登录概念
把复杂的命令执行过程#xff0c;通过逻辑代码#xff0c;组成一个脚本文件的方式就叫做shell脚本。 shebang #! /bin/bash
#! /bin/perl
#! /bin/python执行脚本的方式 source my_first.sh
. my_first.shbash my_first.sh
./my_first.sh变量引用 ${var} 取出变量结果 …概念
把复杂的命令执行过程通过逻辑代码组成一个脚本文件的方式就叫做shell脚本。 shebang #! /bin/bash
#! /bin/perl
#! /bin/python执行脚本的方式 source my_first.sh
. my_first.shbash my_first.sh
./my_first.sh变量引用 ${var} 取出变量结果 $() 在括号中执行命令且拿到命令的执行结果 在括号中执行命令且拿到命令的执行结果 $var 取出变量结果 () 开启子shell执行命令 xiao123xiao123:~/Downloads/shscripts$ echo 当前用户是$(whoami)
当前用户是xiao123
xiao123xiao123:~/Downloads/shscripts$ echo 当前用户是whoami
当前用户是xiao123
xiao123xiao123:~/Downloads/shscripts$ varxiao123
xiao123xiao123:~/Downloads/shscripts$ echo 当前用户是${var}
当前用户是xiao123
xiao123xiao123:~/Downloads/shscripts$ echo 当前用户是$var
当前用户是xiao123
xiao123xiao123:~/Downloads/shscripts$数学计算 支持的运算符展示 Linux用于计算的命令展示 shell基础命令只支持整数小数运算需要使用bc命令 双小括号(())
用法 演示
xiao123xiao123:~/Downloads/shscripts$ echo $((57)) #为True1
1
xiao123xiao123:~/Downloads/shscripts$ echo $((57)) #为Fase0
0
xiao123xiao123:~/Downloads/shscripts$脚本开发 1.想好脚本的功能作用以及需求 2.转换为shell代码 开发一个接收用户输入数字且对运算符号判断最终的出结果的一个计算脚本 接收用户输入对用户输入的不是数字进行判断对输入的运算符进行判断最终进行结果计算输出打印 代码
xiao123xiao123:~/Downloads/shscripts$ cat ./calculation.sh
#! /bin/bashdo_usage() {printf Please input an integer!!!\nexit 1
}read -p Please input first number: firstif [ -n echo ${first}|sed s/[0-9]//g ];
thendo_usage
firead -p Please input an operator: operatorif [ ${operator} ! ] [ ${operator} ! - ] [ ${operator} ! / ] [ ${operator} ! * ];
thenecho Please input [/-/*//]!!!exit 2
firead -p Please input second number: secondif [ -n echo ${second}|sed s/[0-9]//g ];
thendo_usage
fiecho ${first}${operator}${second} $((${first}${operator}${second}))
xiao123xiao123:~/Downloads/shscripts$运行结果
xiao123xiao123:~/Downloads/shscripts$ ./calculation.sh
Please input first number: qew123
Please input an integer!!!
xiao123xiao123:~/Downloads/shscripts$ ./calculation.sh
Please input first number: 123
Please input an operator: eeee
Please input [/-/*//]!!!
xiao123xiao123:~/Downloads/shscripts$ ./calculation.sh
Please input first number: 123
Please input an operator:
Please input second number: 12
12312 135
xiao123xiao123:~/Downloads/shscripts$let命令运算 let命令的执行效果等同于双小括号(()) 但是双小括号(())效率更高 #对比
xiao123xiao123:~/Downloads/shscripts$ num5
xiao123xiao123:~/Downloads/shscripts$ numnum5
xiao123xiao123:~/Downloads/shscripts$ echo ${num}
num5
xiao123xiao123:~/Downloads/shscripts$ num55
xiao123xiao123:~/Downloads/shscripts$ echo ${num}
55
xiao123xiao123:~/Downloads/shscripts$
#let命令
xiao123xiao123:~/Downloads/shscripts$ num5
xiao123xiao123:~/Downloads/shscripts$ let numnum5
xiao123xiao123:~/Downloads/shscripts$ echo ${num}
10
xiao123xiao123:~/Downloads/shscripts$ let num55
xiao123xiao123:~/Downloads/shscripts$ echo ${num}
10
xiao123xiao123:~/Downloads/shscripts$脚本开发对于nginx运行状态检测 #! /bin/bashCheckUrl(){timeout5fails0success0while truedowget --timeout${timeout} --tries1 http://www.baidu.com -q -o /dev/nullif [ $? -ne 0 ];thenlet failsfails1elselet successsuccess1fiif [ ${success} -ge 1 ];thenecho 恭喜你服务运行正常exit 0fiif [ ${fails} -ge 2 ];thenecho 糟糕了服务运行异常请检查服务器状态exit 2fidone
}CheckUrl# 运行结果
xiao123xiao123:~/Downloads/shscripts$ ./let_test.sh
恭喜你服务运行正常
xiao123xiao123:~/Downloads/shscripts$expr命令
简单的计算器执行命令。
xiao123xiao123:~/Downloads/shscripts$ expr --help
Usage: expr EXPRESSIONor: expr OPTION--help display this help and exit--version output version information and exitPrint the value of EXPRESSION to standard output. A blank line below
separates increasing precedence groups. EXPRESSION may be:ARG1 | ARG2 ARG1 if it is neither null nor 0, otherwise ARG2ARG1 ARG2 ARG1 if neither argument is null or 0, otherwise 0ARG1 ARG2 ARG1 is less than ARG2ARG1 ARG2 ARG1 is less than or equal to ARG2ARG1 ARG2 ARG1 is equal to ARG2ARG1 ! ARG2 ARG1 is unequal to ARG2ARG1 ARG2 ARG1 is greater than or equal to ARG2ARG1 ARG2 ARG1 is greater than ARG2ARG1 ARG2 arithmetic sum of ARG1 and ARG2ARG1 - ARG2 arithmetic difference of ARG1 and ARG2ARG1 * ARG2 arithmetic product of ARG1 and ARG2ARG1 / ARG2 arithmetic quotient of ARG1 divided by ARG2ARG1 % ARG2 arithmetic remainder of ARG1 divided by ARG2STRING : REGEXP anchored pattern match of REGEXP in STRINGmatch STRING REGEXP same as STRING : REGEXPsubstr STRING POS LENGTH substring of STRING, POS counted from 1index STRING CHARS index in STRING where any CHARS is found, or 0length STRING length of STRING TOKEN interpret TOKEN as a string, even if it is akeyword like match or an operator like /( EXPRESSION ) value of EXPRESSIONBeware that many operators need to be escaped or quoted for shells.
Comparisons are arithmetic if both ARGs are numbers, else lexicographical.
Pattern matches return the string matched between \( and \) or null; if
\( and \) are not used, they return the number of characters matched or 0.Exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null
or 0, 2 if EXPRESSION is syntactically invalid, and 3 if an error occurred.GNU coreutils online help: https://www.gnu.org/software/coreutils/
Report any translation bugs to https://translationproject.org/team/
Full documentation https://www.gnu.org/software/coreutils/expr
or available locally via: info (coreutils) expr invocation
xiao123xiao123:~/Downloads/shscripts$实践 运算
expr 命令并不是很好用基于空格传输参数但是在shell中一些元字符都是有特殊含义的。
xiao123xiao123:~/Downloads/shscripts$ expr 5 \ 3
8
xiao123xiao123:~/Downloads/shscripts$ expr 5 \- 3
2
xiao123xiao123:~/Downloads/shscripts$ expr 5 \* 3
15
xiao123xiao123:~/Downloads/shscripts$ expr 5 \/ 3
1
xiao123xiao123:~/Downloads/shscripts$求长度
xiao123xiao123:~/Downloads/shscripts$ expr length 123456789
9
xiao123xiao123:~/Downloads/shscripts$逻辑运算
xiao123xiao123:~/Downloads/shscripts$ expr 5 \ 6
0
xiao123xiao123:~/Downloads/shscripts$ expr 5 \ 6
1
xiao123xiao123:~/Downloads/shscripts$模式匹配 2个特殊符号
: 冒号计算字符串字符的数量Yuchao 6个字符.* 任意字符重复0次或者多次 语法 expr 字符串 “:” “.*” xiao123xiao123:~/Downloads/shscripts$ expr yc.png : .*
6
xiao123xiao123:~/Downloads/shscripts$ expr yc.png : .* #统计文件中字符个数
6
xiao123xiao123:~/Downloads/shscripts$ expr yc.png : .*j #最后的模式可以自定义
0
xiao123xiao123:~/Downloads/shscripts$ expr yc.png : p.* #最后的模式可以自定义
0
xiao123xiao123:~/Downloads/shscripts$ expr yc.png : y.* #最后的模式可以自定义
6
xiao123xiao123:~/Downloads/shscripts$ expr yc.png : .*p #最后的模式可以自定义
4
xiao123xiao123:~/Downloads/shscripts$脚本开发 需求执行脚本传入一个文件名然后判断该文件是否是jpg图片文件 xiao123xiao123:~/Downloads/shscripts$ ./expr_test.sh chaochao_1.jpg
这的确是chaochao_1.jpg结尾的文件
xiao123xiao123:~/Downloads/shscripts$ cat ./expr_test.sh
#! /bin/bashif expr $1 : .*\.jpg /dev/nullthenecho 这的确是$1结尾的文件
elseecho 这不是jpg结尾的文件
fi
xiao123xiao123:~/Downloads/shscripts$找出长度不大于为5的单词 xiao123xiao123:~/Downloads/shscripts$ ./expr_test1.sh
I
am
Yu
I
you
to
xiao123xiao123:~/Downloads/shscripts$ cat ./expr_test1.sh
#! /bin/bashfor str1 in I am Yu chao, I teach you to learn linux.doif [ expr length ${str1} -lt 5 ]thenecho ${str1}fidone
xiao123xiao123:~/Downloads/shscripts$bc 命令 bc计算器 awk支持数值计算 中括号运算 bc当作计算器来用的命令行的计算器。 例子1
xiao123xiao123:~/Downloads/shscripts$ bc
bc 1.07.1
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type warranty.
22
4
4*4
16
1-1
0
1-2
-1
2.24/2
1
2.2/2.0
1
2.22-1.1
1.12
^C
(interrupt) use quit to exit.
exit
0
^C
(interrupt) use quit to exit.
quit
xiao123xiao123:~/Downloads/shscripts$例子2
xiao123xiao123:~/Downloads/shscripts$ num5
xiao123xiao123:~/Downloads/shscripts$ echo ${num}*5 | bc
25
xiao123xiao123:~/Downloads/shscripts$案例 计算出1-1000的总和 数学公式 1234…100 xiao123xiao123:~/Downloads/shscripts$ echo {1..100}
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
xiao123xiao123:~/Downloads/shscripts$ #tr 替换
xiao123xiao123:~/Downloads/shscripts$ echo {1..100} | tr #方案1
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100
xiao123xiao123:~/Downloads/shscripts$ seq -s 100 #方案2
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100
xiao123xiao123:~/Downloads/shscripts$
xiao123xiao123:~/Downloads/shscripts$ echo {1..100} | tr | bc
5050
xiao123xiao123:~/Downloads/shscripts$
xiao123xiao123:~/Downloads/shscripts$ echo $((echo {1..100} | tr ))
5050
xiao123xiao123:~/Downloads/shscripts$
xiao123xiao123:~/Downloads/shscripts$ seq -s 100 | xargs expr
5050
xiao123xiao123:~/Downloads/shscripts$awk计算
awk支持小数计算。
xiao123xiao123:~/Downloads/shscripts$ seq -s 100 | xargs expr
5050
xiao123xiao123:~/Downloads/shscripts$ echo 2.2 3.0 | awk {print $1*$2}
6.6
xiao123xiao123:~/Downloads/shscripts$ echo 2.2 3.0 | awk {print ($1*$2)}
6.6
xiao123xiao123:~/Downloads/shscripts$ echo 2.2 3.0 | awk {print ($1*$2)4}
10.6
xiao123xiao123:~/Downloads/shscripts$ echo 2.2 3.0 | awk {print $1*$24}
10.6
xiao123xiao123:~/Downloads/shscripts$中括号计算
$[表达式]
xiao123xiao123:~/Downloads/shscripts$ num5
xiao123xiao123:~/Downloads/shscripts$ res$[num4]
xiao123xiao123:~/Downloads/shscripts$ echo ${res}
9
xiao123xiao123:~/Downloads/shscripts$ res$[num-4]
xiao123xiao123:~/Downloads/shscripts$ echo ${res}
1
xiao123xiao123:~/Downloads/shscripts$ res$[num*4]
xiao123xiao123:~/Downloads/shscripts$ echo ${res}
20
xiao123xiao123:~/Downloads/shscripts$ res$[num/4]
xiao123xiao123:~/Downloads/shscripts$ echo ${res}
1
xiao123xiao123:~/Downloads/shscripts$
