How to find first empty line and delete with in the file using sed command regular expression

Question

I need to find the first empty line in the text file using the sed command regular expression.

below is the content that I have


this is defile
to be cleaned
skip rest consl

In the above content, I need to find only the first line that is an empty line and delete the first line.

I have used below regular expression, but it did not work for me, it is finding empty lines everywhere in the file.

^\s*$

How and where are you coding in what language? Can you share your codes/demo/efforts? — Pushpesh Kumar Rajwanshi, Mar 22 '19 at 11:48
Do you need content of the first empty line, or its position, or what? — Mikhail Vladimirov, Mar 22 '19 at 11:50
Try `(?m)\A\s*$`, it will only match the first line if it is blank. — Wiktor Stribiżew, Mar 22 '19 at 11:56
If you want to find the first blank line in a text editor and replace it use `^\s*$([\s\S]*)` and replace with `New line$1` — Wiktor Stribiżew, Mar 22 '19 at 12:05
@ Pushpesh Kumar Rajwanshi - I need the code with ```sed``` command in linux — moong, Mar 22 '19 at 12:12
@ Wiktor Stribiżew - as per your answer I have the following sed command. ```sed -i '/(?m)\A\s*$/d' file.txt``` but it is not deleting the first line — moong, Mar 22 '19 at 12:29

score 0 · Answer 1 · answered Mar 22 '19 at 11:53

0

In Java you do something like this:

Pattern pattern = Pattern.compile ("^\\s*$", Pattern.MULTILINE);
Matcher matcher = pattern.matcher ("foo\n  \nbar");
if (matcher.find()) {
    String firstEmptyLine = matcher.group();
    ...
}

answered Mar 22 '19 at 11:53

Mikhail Vladimirov

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Mikhail - I need ```sed``` command – moong Mar 22 '19 at 12:14
And what do you need `sed` to do with first empty line? – Mikhail Vladimirov Mar 22 '19 at 12:18
I want to delete the first empty line – moong Mar 22 '19 at 12:19

How to find first empty line and delete with in the file using sed command regular expression

1 Answers1