How to return only the portion of a line after a matching pattern?
So pulling open a file with cat and then using grep to get matching lines only gets me so far when I am working with the particular log set that I am dealing with. It need a way to match lines to a pattern, but only to return the portion of the line after the match. The portion before and after the match will consistently vary.
How to print two lines after a pattern?
The simplest is using the grep command. In GNU grep, there is an option -A which prints lines following the pattern. In the above example, -A1 will print one line following the pattern along with the line matching the pattern. To print 2 lines after the pattern, it is -A2.
How to remove a line after a match?
Sometimes you’ll want to remove the portion of the line after the match. You can include it in the match by including .*$ at the end of the pattern (any text .* followed by the end of the line $ ). Unless you put that part in a group that you reference in the replacement text, the end of the line will not be in the output.
Is there way to filter before and after matches?
The portion before and after the match will consistently vary. I have played with using sed or awk, but have not been able to figure out how to filter the line to either delete the part before the match, or just return the part after the match, either will work. This is an example of a line that I need to filter:
How to return only line numbers in grep?
I would like to use grep to return only the line numbers where this occurs (as in, the match was here, go to line # x and fix it). However, there doesn’t seem to be a way to print the line number ( grep -n) and not the match or line itself.
How to test if there are files matching a pattern?
I am trying to write an if statement to test whether there are any files matching a certain pattern. If there is a text file in a directory it should run a given script. Please give some ideas; I only want to run the script if there is a .txt in the directory.
How to make a pattern match in Java?
And the standard Java escape sequence \ nnnn is used to specify a Unicode character in the pattern. We use methods of java.lang.Character to determine Unicode character properties, such as whether a given character is a space.
When to use a backreference in text processing?
If you want to retain the matching portion, use a backreference: \\1 in the replacement part designates what is inside a group \\ (…\\) in the pattern. Here, you could write stalled: again in the replacement part; this feature is useful when the pattern you’re looking for is more general than a simple string.
How to return the whole line using regex?
Surround your regex phrase with .* and .* so that it pick up the entire line. string pattern = “.*foobar.*”; Regex r = new Regex (pattern) foreach (Match m in r.Matches (input)) { Console.WriteLine (m.Value); } Yes, this is possible. You can use the following: