删除文本文件奇数或偶数行，在Linux终端 [英] remove odd or even lines from text file in terminal in linux

问题描述

我需要删除奇数行的文本文件，以使下采样。我发现这个命令，

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

但只打印终端中的奇数行。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，我希望他们从文件中删除，或在另一个文件打印。仅打印他们在终端。

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

的％是一个模操作符和 NR 是当前行号，所以 NR％2 == 0 仅在偶数行的真实，将调用它们的默认规则（ {$打印0} ）。因此，要的只保存偶数行的，从重定向 AWK 输出到一个新文件：

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

您可以用完成 SED 同样的事情。 的 devnulls 的的回答显示了如何 sed的GNU 。
下面是版本替代 SED 不具备的〜运营商：

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:

的删除偶数行的

sed 'n; d' infile  # output ODD lines only

的删除奇数行的

sed '1d; n; d' infile  # output EVEN lines only

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