How do you grep lines below?
To also show you the lines before your matches, you can add -B to your grep. The -B 4 tells grep to also show the 4 lines before the match. Alternatively, to show the log lines that match after the keyword, use the -A parameter. In this example, it will tell grep to also show the 2 lines after the match.
How do you grep 3 lines after a match?
For BSD or GNU grep you can use -B num to set how many lines before the match and -A num for the number of lines after the match. If you want the same number of lines before and after you can use -C num . This will show 3 lines before and 3 lines after.
How to show lines before and after a match in grep?
You can add some additional parameters to your grep command, to search for keywords or phrases in files, to also show you the files that match before or after your match. This is especially useful if the lines before or after that match are relevant for your search queries. A normal grep looks like this.
When to use Grep and not match multiple patterns?
Using sed command: GREP AND: Match Multiple Patterns. It is also often required to grep a file for multiple patterns – when it is needed to find all the lines in a file, that contain not one, but several patterns. Note, that you can both find the lines in a file that match multiple patterns in the exact order or in the any order.
Which is the only file to be checked by grep?
As the output above shows, only files with the file extension “log” are checked by the grep command. We’ve used two options to tell the grep command to do that: -R will search files recursively. That is, it’s going to search the given pattern in files in any subdirectory under test
How to ignore a case when using grep?
Ignore Case when Using Grep for Multiple Strings. To avoid missing something when you search for multiple patterns, use the -i flag to ignore letter case. For example, we will ignore case with this command: grep -i ‘phoenix\\|linux’ sample.txt