从文本文件中删除奇数或偶数行 [英] Remove odd or even lines from a text file

问题描述

我需要删除文本文件中的奇数行以进行下采样.我找到了这个命令，

I need to remove odd lines in a text file to make a down-sampling. I've found this command,

awk 'NR%2==0' file

但它只在终端中打印奇数行.如何真正删除它们?

but it only prints the odd lines in the terminal. How to really remove them?

我真的不关心偶数或奇数，我希望它们从文件中删除或打印在另一个文件中.这只会在终端中打印它们.

I don't really care for even or odd, I want them removed from the file or printed in another file. This only prints them in the terminal.

推荐答案

awk

% 是模运算符，NR 是当前行号，所以 NR%2==0 仅对偶数为真行并将为其调用默认规则({ print $0 }).因此，为了只保存偶数行，将 awk 的输出重定向到一个新文件:

awk

The % is a modulus operator and NR is the current line number, so NR%2==0 is true only for even lines and will invoke the default rule for them ({ print $0 }). Thus to save only the even lines, redirect the output from awk to a new file:

awk 'NR%2==0' infile > outfile

sed

你可以用 sed 完成同样的事情.devnulls 答案显示了如何使用 GNU sed.以下是没有 ~ 运算符的 sed 版本的替代方案:

sed

You can accomplish the same thing with sed. devnulls answer shows how to do it with GNU sed. Below are alternatives for versions of sed that do not have the ~ operator:

保留奇数行

sed 'n; d' infile > outfile

保持连线

sed '1d; n; d' infile > outfile

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