Rhcsa operation

1. Pipe exercise ： take echo "This is my first time to use pipe" Output content to the screen , And save it to pipe_data.txt in

[[email protected] ~]# echo "This is my first time to use pipe" | tee pipe_data.txt
This is my first time to use pipe
[[email protected] ~]# more pipe_data.txt
This is my first time to use pipe
​

1. Redirect ： a. Create a new file redirect.txt, And write in it 20210804RHCSA, Save and exit b. take cat redirect.txt The output of is redirected to redirect1.txt in c. take cat redirect.txt noexist.txt Standard output of redirected to redirect2.txt, The standard error output is redirected to error1.txt d. take cat redirect.txt noexist.txt Both standard output and error output are directed from redirect3.txt in e. Input redirection ： Will enter... From the keyboard Welcome to my zone. Line break YYDS Then input EOF End keyboard input , And redirect to my_input.txt in

   ​
   vim redirect.txt
   20210804RHCSA
   [[email protected] ~]# more redirect.txt
   20210804RHCSA
   [[email protected] ~]# cat redirect.txt 1> redirect3.txt
   [[email protected] ~]# cat redirect.txt 2>> redirect3.txt
   ​
   ​
   ​
   d. take cat redirect.txt noexist.txt Both standard output and error output are directed from redirect3.txt in 
   [[email protected] ~]# cat redirect.txt noexist.txt &> redirect3.txt
   [[email protected] ~]# more redirect3.txt 
   20210804RHCSA
   cat: noexist.txt:  There is no file or directory 
   ​
   e. Input redirection ： Will enter... From the keyboard Welcome to my zone. Line break 
       YYDS
    Then input EOF End keyboard input , And redirect to my_input.txt in 
   [[email protected] ~]# cat >> my_input.txt << EOF
   > Welcome to my zone
   > YYDS'
   > EOF
   [[email protected] ~]# more my_input.txt 
   Welcome to my zone
   YYDS'
   ​

3. File content browsing a.cat see /etc/passwd The contents of the document , And output with line number

cat -n /etc/passwd

Use more/less see /etc/passwd Content , And each page displays 10 That's ok

more -10 /etc/passwd/
less -10 /etc/passwd/

c. Use head/tail Before viewing the files separately 5 Line content and after 5 Row content

[[email protected] ~]# head -5  /etc/passwd 
[[email protected] ~]# tail -5  /etc/passwd 

d. Use grep see /etc/passwd neutralization root Related content

[[email protected] ~]# grep root  /etc/passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
​