如何使用 Linux/Unix 将文本文件中以某个字符开头的行替换为空行？

发布于 2025-01-13 13:23:43 字数 300 浏览 0 评论 0原文

我正在使用 Ubuntu，并且有一个大型文本文件，其中某些行以 < 字符开头，我想将其中的每一个替换为空行。因此，

eeeeee
<
<
aaaa
bbbb
cccc
<
dddddd
<
ff

我想要这样：（

eeee

aaaa
bbbb
cccc

dddddd

ff

如果有多个连续 < 行，理想情况下只需要一个空行）

如何在命令行中执行此操作？

原文

I'm using Ubuntu and have a large text file where certain rows start with < character what I'd like to replace each of these to an empty row. So from this:

eeeeee
<
<
aaaa
bbbb
cccc
<
dddddd
<
ff

I want this:

eeee

aaaa
bbbb
cccc

dddddd

ff

(In case of multiple consecutive < rows only one empty rows is needed ideally)

How to perform this in command line?

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天冷不及心凉 2025-01-20 13:23:43

这个 Perl 一行代码应该可以满足您的要求：

perl -ne 'if (/^</) {print "\n" if !$f; $f=1} else {$f=0; print}' tmp.txt

它正在运行：

# cat tmp.txt
eeeeee
<
<
aaaa
bbbb
cccc
<
dddddd
<
ff
# perl -ne 'if (/^</) {print "\n" if !$f; $f=1} else {$f=0; print}' tmp.txt
eeeeee

aaaa
bbbb
cccc

dddddd

ff

注释代码：

# Found a line starting with '<'
if (/^</) {
    # Print a blank line if $f is false
    print "\n" if !$f;
    # Set $f to true so subsequent lines starting with '<' are ignored
    $f=1;
} else {
    # Not a line starting with '<'; reset $f to false
    $f=0;
    # Print the current line
    print;
}

This Perl one-liner should do what you're asking for:

perl -ne 'if (/^</) {print "\n" if !$f; $f=1} else {$f=0; print}' tmp.txt

Here it is in action:

# cat tmp.txt
eeeeee
<
<
aaaa
bbbb
cccc
<
dddddd
<
ff
# perl -ne 'if (/^</) {print "\n" if !$f; $f=1} else {$f=0; print}' tmp.txt
eeeeee

aaaa
bbbb
cccc

dddddd

ff

Commented code:

# Found a line starting with '<'
if (/^</) {
    # Print a blank line if $f is false
    print "\n" if !$f;
    # Set $f to true so subsequent lines starting with '<' are ignored
    $f=1;
} else {
    # Not a line starting with '<'; reset $f to false
    $f=0;
    # Print the current line
    print;
}

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