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Grep tool

2022-06-29 22:28:00 【51CTO】

Course objectives of this section

● understand shell Wildcard in

● be familiar with grep、cut、sort And other gadgets shell Wildcard in Use

One 、 Text processing tools

1. grep Tools

grep yes ** That's ok ** Filter tool ; Used to filter lines according to keywords

Grammar and options

grammar

      
      
       
       grep [ Options ] ' keyword '  file name 
      
      
      
      
       
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Common options ：

      
      
       
       OPTIONS:
       
       
    -i:  Case insensitive 
       
       
    -v:  Find lines that do not contain the specified content , Reverse selection 
       
       
    -w:  Search by word 
       
       
    -o:  Print matching keywords 
       
       
    -c:  Count the number of rows matched 
       
       
    -n:  According to the line Numbers 
       
       
    -r:  Traverse the directory layer by layer to find 
       
       
    -A:  Show matching lines and how many lines follow  
       
       
    -B:  Show matching lines and how many lines ahead 
       
       
    -C:  Show how many lines before and after the match line 
       
       
    -l： Only matching file names are listed 
       
       
    -L： List mismatched filenames 
       
       
    -e:  Use regular matching 
       
       
    -E: Use extended regular matching 
       
       
    ^key: Start with a keyword 
       
       
    key$: End with keywords 
       
       
    ^$: Match blank line 
       
       
    --color=auto ： You can add color to the key words you find 
      
      
      
      
       
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Color display （ The alias set ）：

      
      
       
        Temporary settings ：
       
       
# alias grep='grep --color=auto'      // Only valid for current terminal and current user 
       
       
 Permanent settings ：
       
       
1） overall situation （ Effective for all users ）
       
       
vim /etc/bashrc
       
       
alias grep='grep --color=auto'
       
       
source /etc/bashrc
       
       
2） Local （ For a specific user ）
       
       
vim ~/.bashrc
       
       
alias grep='grep --color=auto'
       
       
source ~/.bashrc
      
      
      
      
       
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Illustrate with examples ：

explain ： Don't use... Directly /etc/passwd file , Copy it to /tmp Next experiment ！

# grep -i root passwd Ignore case matching to include root The line of

# grep -w ftp passwd Exactly match ftp word

# grep -w hello passwd Exactly match hello word ; Add your own include hello Line to file

# grep -wo ftp passwd Print matching keywords ftp

# grep -n root passwd Print match to root Good keyword

# grep -ni root passwd Ignore case matching statistics including keywords root The line of

# grep -nic root passwd Ignore case matching statistics including keywords root The number of rows

# grep -i ^root passwd Ignore case matching to root Beginning line

# grep bash$ passwd Match with bash The line at the end

# grep -n ^$ passwd Match blank lines and print line numbers

# grep ^# /etc/vsftpd/vsftpd.conf Match with # The line at the beginning of the number

# grep -v ^# /etc/vsftpd/vsftpd.conf Match not to # The line at the beginning of the number

# grep -A 5 mail passwd Matching inclusion mail Keywords and after 5 That's ok

# grep -B 5 mail passwd Matching inclusion mail Keywords and before 5 That's ok

# grep -C 5 mail passwd Matching inclusion mail Keywords and before and after 5 That's ok

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2. cut Tools

cut yes ** Column ** Interception tools , For column truncation

Grammar and options

grammar ：

      
      
       
       # cut  Options    file name 
      
      
      
      
       
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Common options ：

      
      
       
       -c:  Split in characters , Intercept 
       
       
-d:  Custom delimiter , The default is tab \t
       
       
-f:  And -d Use it together , Specify which area to intercept 
      
      
      
      
       
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Illustrate with examples :

      
      
       
       # cut -d: -f1 1.txt        With : Colon division , Cut off the 1 Column content 
       
       
# cut -d: -f1,6,7 1.txt    With : Colon division , Cut off the 1,6,7 Column content 
       
       
# cut -c4 1.txt          Intercept every line in the file 4 Characters 
       
       
# cut -c1-4 1.txt        Intercept each line of the file 1-4 Characters 
       
       
# cut -c4-10 1.txt       Intercept each line of the file 4-10 Characters 
       
       
# cut -c5- 1.txt         From 5 Characters begin to intercept all the following characters 
      
      
      
      
       
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Class practice ： Use a gadget to list the operating levels of your current system .5/3

How to view the system operation level

command runlevel
file /etc/inittab

How to filter run levels

      
      
       
       runlevel |cut -c3
       
       
runlevel | cut -d ' ' -f2
       
       
grep -v '^#' /etc/inittab | cut -d: -f2
       
       
grep '^id' /etc/inittab |cut -d: -f2
       
       
grep "initdefault:$" /etc/inittab | cut -c4
       
       
grep -v ^# /etc/inittab |cut -c4
       
       
grep 'id:' /etc/inittab |cut -d: -f2
       
       
cut -d':' -f2 /etc/inittab |grep -v ^#
       
       
cut -c4 /etc/inittab |tail -1
       
       
cut -d: -f2 /etc/inittab |tail -1
      
      
      
      
       
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