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How to grep multiline search patterns in Linux?
In order to be able to grep multiple lines of pattern present in a file, we will make use of the number of grep command that Linux provides us with. But first, we must understand what a grep command is and how to use it on Linux.
The grep command in Linux is used to filter searches in a file for a particular pattern of characters. It is one of the most used Linux utility commands to display the lines that contain the pattern that we are trying to search.
Normally, the pattern that we are trying to search in the file is referred to as the regular expression.
Syntax
grep [options] pattern [files]
While there are plenty of different options available to us, some of the most used are −
-c : It lists only a count of the lines that match a pattern -h : displays the matched lines only. -i : Ignores, case for matching -l : prints filenames only -n : Display the matched lines and their line numbers. -v : It prints out all the lines that do not match the pattern
Now, let’s consider a case where we want to find a particular pattern in all the files in a particular directory, say dir1.
Syntax
grep -rni "word" *
In the above command replace the “word” placeholder with
For that we make use of the command shown below −
Command
grep -rni "func main()" *
The above command will try to find a string “func main()” in all the files in a particular directory and also in the subdirectories as well.
Output
main.go:120:func main() {}
In case we only want to find a particular pattern in a single directory and not the subdirectories then we need to use the command shown below −
grep -s "func main()" *
Now suppose we have a text file named sample.txt whose content looks something like this.
$ immukul@192 linux-questions-code % cat sample.txt blabla blabla foofoo here is the text2strike Just a pattern bar blabla blabla
Now the command to search for multiline pattern is shown below
grep -Pzo "(?s)^(\s*)\N*/foo/,/bar/p.*?{.*?^\1}" .txtOutput
foofoo here is the text2strike just a pattern bar
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