2/14 (regular expression, sed streaming editor)

Regular expressions

1.

head -5 /etc/passwd > user # Prepare the material

grep “[root]” user # look for r、o、t Any character
grep “[rot]” user # The effect same as above
grep “[^rot]” user # Show r or o or t Beyond
grep “[0123456789]” user # Find all the numbers
grep “[0-9]” user # The effect same as above
grep “[^0-9]” user # Show content other than numbers
grep “[a-z]” user # Find all lowercase letters
grep “[A-Z]” user # Find all capital letters
grep “[a-Z]” user # Find all the letters
grep “[^0-9a-Z]” user # Find all the symbols

grep “.” user # Find any single character , Every character in the document can be understood as any character
grep “r…t” user # look for rt There are 2 A line of arbitrary characters
grep “r.t” user # look for rt There are 1 A line of arbitrary characters , There is no match , There is no output
grep “" user # Incorrect usage , The number matches the previous character any time , Not to be used alone
grep "rot" user # look for rt, In the middle of the o It's ok if there's any , A few times will do
grep ".” user # Find any , Including the empty line . And * The combination of is equivalent to the effect of wildcards in regularization

grep “ro{1,2}t” user # look for rt, In the middle of the o There can be 1~2 individual
grep “ro{2,6}t” user # look for rt, In the middle of the o There can be 2~6 individual
grep “ro{1,}t” user # look for rt, In the middle of the o There can be 1 And 1 More than
grep “ro{3}t” user # look for rt, In the middle of the o There must be only 3 individual

2.

All the above commands can add -E Option and remove all \, Change to the extended regular usage , such as
grep “ro{1,}t” user You can change to grep -E “ro{1,}t” user
perhaps egrep “ro{1,}t” user

grep “ro{1,}t” user # Using basic regular search o appear 1 Times and 1 More than once
egrep “ro{1,}t” user # Using extended regularization , The effect same as above , It is relatively concise
egrep “ro+t” user # Using extended regularization , The effect same as above , Minimalist
grep “roo{0,1}t” user # Use basic regularity to find the second o appear 0~1 Time
egrep “roo{0,1}t” user # Using extended regularization , The effect same as above , It is relatively concise
egrep “roo?t” user # Using extended regularization , The effect same as above , Minimalist

egrep “({2}” user # Find continuous 2 individual 0: The function of parentheses is to combine characters into a whole

egrep “root|bin” user // Look for root perhaps bin The line of

egrep “the\b” abc.txt // stay abc.txt Find... In the file the, The right side is not allowed to go out
Now the number 、 Letter 、 Underline
egrep “\bthe\b” abc.txt // Numbers are not allowed on either side 、 Letter 、 Underline
egrep “<the>” abc.txt // The effect same as above

sed Streaming editor

1, Pre instruction | sed Options Conditions Instructions
2,sed Options Conditions Instructions Processed documents
Options -n Mask default output -r Support extended regularization -i Modify source file
Instructions p Output d Delete s Replace
Conditions Line number / character string /

1) p Output
sed -n ‘p’ user # Output all lines
sed -n ‘1p’ user # Output No 1 That's ok
sed -n ‘2p’ user # Output No 2 That's ok
sed -n ‘3p’ user # Output No 3 That's ok

sed -n ‘2,4p’ user # Output 2~4 That's ok
sed -n ‘2p;4p’ user # Output No 2 Lines and 4 That's ok

sed -n ‘3,+1p’ user # Output No 3 Lines and after 1 That's ok

sed -n ‘/^root/p’ user # Output to root Beginning line
sed -n ‘/root/p’ user # The output contains root The line of
sed -nr ‘/^root|bin/p’ user # Output to root The first line or bin Beginning line ,| It's extended regular , need r Options
sed -n ‘1!p’ user # Output in addition to 1 The content of the line ,! It's a reversal
sed -n 'KaTeX parse error: Expected 'EOF', got '#' at position 11: p' user #̲ Output the last line sed -n '…= It's the line number of the last line
sed -n ‘$=’ user # Total rows of output file

2) d Delete （ If you remove -n, Will be p Change the command to d The instruction is to delete ）
Delete the first 3~5 That's ok sed ‘3,5d’ user
Delete all include xml The line of sed ‘/xml/d’ user
Delete does not contain xml The line of sed ‘/xml/!d’ user
Delete with install Beginning line sed ‘/^install/d’ user
Delete the last line of the file sed ‘$d^{\prime }userDeleteexceptThe\; first35That\text{'}s\; okse{d}^{\prime }3,5d^{\prime }abc.txtDeleteexcepttheYespackagecontainxmlOfThat\text{'}s\; okse{d}^{\prime }/xml/d^{\prime }abc.txtDeleteexceptNopackagecontainxmlOfThat\text{'}s\; okse{d}^{\prime }/xml/!d^{\prime }abc.txtDeleteexceptWithinstallopenheadOfThat\text{'}s\; okse{d}^{\prime }{/}^{i}nstall/d^{\prime }abc.txtDeleteexceptwritingPieces\; ofOfmostafterOneThat\text{'}s\; okse{d}^{\prime }$d’ user
Delete all blank lines sed ‘/^$/d’ user

3）s Replace
sed ‘s/2017/6666/’ shu.txt # Put the first of all lines 1 individual 2017 Replace with 6666
sed ‘s/2017/6666/2’ shu.txt # Put the first of all lines 2 individual 2017 Replace with 6666
sed ‘1s/2017/6666/’ shu.txt # The first 1 OK, No 1 individual 2017 Replace with 6666
sed ‘3s/2017/6666/3’ shu.txt # The first 3 OK, No 3 individual 2017 Replace with 6666
sed ‘s/2017/6666/g’ shu.txt # All... Lines 2017 Replace all
sed ‘/2024/s/2017/6666/g’ shu.txt # Find something that contains 2024 The line of , Put everything in it 2017 Replace with 6666

Example ： If you want to put the /bin/bash Replace with /sbin/sh How to operate ？
sed -i ‘1s/bin/sbin/’ user // Traditional methods can be changed one by one , Change one first
sed -i ‘1s/bash/sh/’ user // Another one

sed ‘s!/bin/bash!/sbin/sh!’ user // Best solution , change s The replacement character of
sed ‘s(/bin/bash(/sbin/sh(’ user // The replacement symbol can use the... On all numeric keys

Write a script , build httpd service , use 82 Port number opens the service

yum -y install httpd &> /dev/null // Install web site
echo “sed-test~~~” > /var/www/html/index.html // Define the default page
sed -i ‘/^Listen 80/s/0/2/’ /etc/httpd/conf/httpd.conf // Modify the configuration file , Change the listening port to 82

Then run the script
curl 192.168.2.5:82 // After the script runs , test 82 The port can see the page
sed-test~~~