淺談Shell腳本參數與交互及常見問題

[root@localhost 20190105]# vi paral.sh
#!/bin/bash
#顯示腳本名
echo 'The script name is '$0
#顯示第1個參數
echo 'The 1th parameter is '$1
#顯示第2個參數
echo 'The 2th parameter is '$2
#顯示第3個參數
echo 'The 3th parameter is '$3
#顯示第4個參數
echo 'The 4th parameter is '$4
#顯示第5個參數
echo 'The 5th parameter is '$5
#顯示第6個參數
echo 'The 6th parameter is '$6
#顯示第7個參數
echo 'The 7th parameter is '$7
#顯示第8個參數
echo 'The 8th parameter is '$8
#顯示第9個參數
echo 'The 9th parameter is '$9
[root@localhost 20190105]# ./paral.sh Ni hao , Nice to meet you !
The script name is ./paral.sh
The 1th parameter is Ni
The 2th parameter is hao
The 3th parameter is ,
The 4th parameter is Nice
The 5th parameter is to
The 6th parameter is meet
The 7th parameter is you
The 8th parameter is !
The 9th parameter is      //空值
[root@localhost 20190105]#

read 變量1 [變量2...]

[root@localhost 20190105]# vi read1.sh
#!/bin/bash
#初始化變量的值
input1=''                                               #設置 input1 變量值為空
input2=''                                               #設置 input2 變量值為空
input3=''                                               #設置 input3 變量值為空
input4=''                                               #設置 input4 變量值為空
#until 循環(huán)，當 input1 變量的值為 exit 時退出該循環(huán)
until [ "$input1" = exit ]
do
       echo 'Please input the values:'
#讀取鍵盤輸入的數據
       read input1 input2 input3 input4
#輸入的不是 exit 時把用戶輸入的數據顯示在屏幕上
       if [ "$input1" != exit ]
       then
               echo 'input1: '$input1                  #輸出變量 input1 的值
               echo 'input2: '$input2                  #輸出變量 input2 的值
               echo 'input3: '$input3                  #輸出變量 input3 的值
               echo 'input4: '$input4                  #輸出變量 input4 的值
               echo
#當輸入為 exit 時顯示退出腳本的提示
       else
               echo 'Exit the script.'
       fi
done
[root@localhost 20190105]# chmod +x read1.sh
[root@localhost 20190105]# ./read1.sh
Please input the values:
How do you do           //輸入的數據個數與變量個數相等
input1: How
input2: do
input3: you
input4: do

Please input the values:
Welcome to beijing       //輸入的數據個數小于變量個數
input1: Welcome
input2: to
input3: beijing
input4:

Please input the values:
let's go              //輸入的數據個數小于變量個數
input1: let's
input2: go
input3:
input4:

Please input the values:
Nice to meet you,too!      //輸入的數據個數大于變量個數
input1: Nice
input2: to
input3: meet
input4: you,too!

Please input the values:    //結束程序
exit
Exit the script.
[root@localhost 20190105]#

[root@localhost 20190105]# vi vall.sh
#!/bin/bash
echo 'The value of $# is: '$#           //輸出$#變量的值
echo 'The value of $* is: '$*           //輸出$*變量的值
echo 'The value of $@ is: '$@           //輸出$@變量的值
echo 'The value of $$ is: '$$           //輸出$$變量的值
echo 'The value of $! is: '$!           //輸出$!變量的值
echo 'The value of $- is: '$-           //輸出$-變量的值
echo 'The value of $? is: '$?           //輸出$?變量的值
[root@localhost 20190105]# ./vall.sh how do you do
The value of $# is: 4 //輸出4變量的值
The value of $* is: how do you do //輸出how do you do變量的值
The value of $@ is: how do you do //輸出how do you do變量的值
The value of $$ is: 9040 //輸出9040變量的值
The value of $! is:  //輸出變量的值
The value of $- is: hB //輸出hB變量的值
The value of $? is: 0 //輸出0變量的值
[root@localhost 20190105]#

命令 > /dev/null

命令 2> /dev/null

命令 > /dev/null 2> /dev/null

if grep jack /etc/passwd > /dev/null
then
 echo "jack found"
fi

[root@localhost ~]# ps -ef | grep sshd | awk '{print $2}'
4478
12821
22028

[root@localhost ~]# ps -ef | \

> grep ssh | \

> awk '{print $2}'
4478
12821
23375
[root@localhost ~]#