Linux学习笔记（三）---Shell编程

梦里梦外; 2022-05-31 10:12 248阅读 0赞

shell编程  
    
  test \[options\] file/directory  
  -e  判断该文件或文件夹是否存在  
  -d  判断该文件或文件夹是否是个目录  
  -f  判断该文件或文件夹是够是一个文件  
  
  
  -r  判断该文件是否可可读  
  -w  判断该文件是否可写入  
  -x  判断该文件是否可执行  
  
  
  -eq 相等  
  -ne 不等  
  -gt 大于  
  -lt 小于  
  -le 小于等于  
  -ge 大于等于  
  
  
  test n1 -eq n2  
  
  
  examples:  
test -d /testst && echo "exist" || echo  "Not exist"  
test -f sh01.sh && echo "is a file" || echo "is not a file"  
test -d /demo && echo "is an directory" ||  echo "is not an direcory"  
  
  
  判断字符串：  
  -z  判断该字符串是否为0，若字符串为空，则返回true  
  -n  判断该字符串是否为非0，若字符串为空，则返回false  
  test -z "" && echo "true" || echo "false"  
  >true  
  test -z "testtest" && echo "ture" || echo "false"  
  >false  
  test -n "testtest" && echo "true" || echo "false"  
  >true  
  test -n "" && echo "true" || echo "false"  
  >false  
  
  
  多重条件判断  
  -a  and   
  -o  or  
  !   非  
  
  
  examples:  
  test -r sh01.sh -a -x sh02.sh && echo "have read and execute power" || echo "have no power"  
  test -r sh01.sh -o -w sh03.sh && echo "have read or write power" || echo "oppict"  
  test  ! -r sh01.sh && echo "have read" || echo "非read"  
    
  \[ "gyoomi" == "gyoomi" \] && echo "equal" || echo "not equal"  注意空格  
  
  
  date \[options\] \[+Format\]  
  options:  
  ->  --date=STRING    STRING一般取值:'-1 day' ,'+ 1 month','+20 year'  
  ->  +%Y%m%d  
  date --date="-1 year" %Y%m%d  
  输出结果:  
  >20170119  
  
  
  
  
  \[\]进行判断:  
  \[ "$yn" == "y" \]   满足返回true,否则返回false  
  tips:  
       1.\[\]中的每个组件都要使用空格进行隔开  
       2.\[\]中变量要使用""来引用注  
       3.\[\]中的常量,最好使用""或''来引用注.ps:统一记住成其中的变量和常量来使用""来引用.  
  examples:  
  
  
\------------------------------------start------------------------------------------->  
\#!/bin/bash  
\#Program:  
\#        this is progarm is used for judge what choice you had choosen.  
\#Version:  
\#       author:gyoomi   2018/01/22  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
read -p "please keyin your choice: " yn  
  
  
\#3.0  
\[ "$yn" == "Y" -o "$yn" == "y" \] && echo "ok! continue..." && exit 0  
\[ "$yn" == "N" -o "$yn" == "n" \] && echo "not ok,interrupt!!!" && exit 0  
echo -e "i do not know what your choice!!!" && exit 0  
\---------------------------------end------------------------------------------------>  
  if判断  
  examples:  
\------------------------------------start------------------------------------------->  
\#!/bin/bash  
\#Program:  
\#       this program is used for exectising iffi sentense.  
\#Version:  
\#       gyoomi  2018/01/22  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
  
  
if \[ "$1" == "hello" \]; then  
   echo -e "hi,how are u?"  
elif \[ "$1" == "" \]; then  
   echo "u MUST keyin paramters ex> $0 someword"  
else  
  echo "the only paramter is hello"  
fi  
\---------------------------------end------------------------------------------------>  
  
  
  netstat -tuln  查看当前正在被侦听的ip,端口  
  
  
  
  
  
  
case ...in 语句的使用  
\------------------------------------start------------------------------------------->  
\#!/bin/bash  
\#Program:  
\#       this program is execticing case in...  
\#Version:  
\#      gyoomi  2018/01/24  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
case $1 in  
    "hello")  
           echo "how are you???"  
           ;;  
    "")  
          echo "you MUST keyin paramsters ex> $0 someword"  
           ;;  
    \*)  
          echo "Usage $0 \{hello\}"  
           ;;  
esac  
\---------------------------------end------------------------------------------------>  
  
  
  
  
  
  
function功能的使用  
  
  
\------------------------------------start------------------------------------------->  
\#!/bin/bash  
\#Program:  
\#      this program is used for testing function effect!!  
\#Version:  
\#      gyoomi  2018/01/29  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
function printit()\{  
     echo -e "your choice is $1"  
\}  
  
  
\#3.0  
case $1 in  
      "one")  
           printit 1  
           ;;  
       "two")  
           printit 2  
           ;;  
       "three")  
           printit 3  
           ;;  
       \*)  
           echo -e "Usage $0 \{one|two|three\}"  
esac  
\---------------------------------end------------------------------------------------>  
  
  
循环的使用  
数字:  
\------------------------------------start------------------------------------------->  
\#!/bin/bash  
\#Program:  
\#      this program is used for testing function effect!!  
\#Version:  
\#      gyoomi  2018/01/29  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
s=0  
  
  
\#3.0  
for ((i=1;i<=100;i++));  
do  
    s=$(($s+$i))  
done  
  
  
\#4.0  
echo -e "the sum is: $s"  
\---------------------------------end------------------------------------------------>  
  
  
\#!/bin/bash  
\#Program:  
\#      this program is used for testing while do done!!!  
\#Version:  
\#      gyoomi  2018/01/29  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
i=0  
s=0  
  
  
\#3.0  
while \[ "$i" != "100" \]  
do  
      i=$(($i+1))   
      s=$(($s+$i))  
done  
echo "1+2+3+...+100 is: ==> $s"  
  
  
  
  
  
  
\#!/bin/bash  
\#Program:  
\#      this program is used for testing util do done!!!  
\#Version:  
\#      gyoomi  2018/01/29  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
until \[ "$yn" == "yes" \] || \[ "$yn" == "YES" \]  
do  
     read -p "please key in yes/YES to stop the program:" yn  
done  
  
  
  
  
  
  
  
  
  
  
字符:  
\------------------------------------start------------------------------------------->  
\#!/bin/bash  
\#Program:  
\#      this program is used for testing function effect!!  
\#Version:  
\#      gyoomi  2018/01/29  v1.0 release  
  
  
\#1.0  
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin  
export PATH  
  
  
\#2.0  
s=0  
  
  
\#3.0  
for ((i=1;i<=100;i++));  
do  
    s=$(($s+$i))  
done  
  
  
\#4.0  
echo -e "the sum is: $s"  
\---------------------------------end------------------------------------------------>  
  
  
sudo dhclient  重置网卡  
  
  
  
  
shell脚本的调试和使用  
sh \[-nxv\] script.sh  
\-n 不执行脚本,只检查语法错误  
\-x 执行脚本,并将要使用的脚本的内容输出到屏幕上  
\-v 在执行脚本前,将脚本的内容输入到屏幕上