如何使用awk或grep从不同的行中选择数据？(How to use awk or grep to select data from different lines?)

如何使用awk或grep从不同的行中选择数据？(How to use awk or grep to select data from different lines?)

如果我在脚本中间，当前有这样的管道输入：

text sometext moretext text othertext more somemore futhertext text sometext moretext text othertext more somemore futhertext etc etc (the 2 patterns repeat)

我想选择第一行的2nd列和第二行的4th列，然后管道输出，所以我最终得到：

sometext furthertext

有没有办法做到这一点？ 我知道awk '{print $2}'和awk '{print $4}'存在但是如何让它在不同的行上选择不同的列？

If I'm in the middle of a script which currently has piped input like this:

text sometext moretext text othertext more somemore futhertext text sometext moretext text othertext more somemore futhertext etc etc (the 2 patterns repeat)

and I want to select say the 2nd column for the first line and the 4th column for the second line and then pipe the output so I end up with:

sometext furthertext

Is there a way to do this? I know that awk '{print $2}' and awk '{print $4}' exists but how do I make it select different columns on different lines?

最满意答案

$ awk 'BEGIN{split("2 4",a)} NR in a {print $(a[NR])}' file sometext futhertext

或者如果你想重复每一行和第二行：

$ awk 'BEGIN{n=split("2 4",a)} {print $(a[(NR-1)%n+1])}' file sometext futhertext sometext futhertext etc

如果你想为第3行和第4行做不同的字段，它可以简单地扩展：

$ awk 'BEGIN{n=split("2 4 1 3",a)} {print $(a[(NR-1)%n+1])}' file sometext futhertext text somemore etc $ awk 'BEGIN{split("2 4",a)} NR in a {print $(a[NR])}' file sometext futhertext

or if you want it to repeat for EVERY 1st and 2nd line:

$ awk 'BEGIN{n=split("2 4",a)} {print $(a[(NR-1)%n+1])}' file sometext futhertext sometext futhertext etc

and if you want to do different fields for the 3rd and 4th lines too, it's trivially extensible:

$ awk 'BEGIN{n=split("2 4 1 3",a)} {print $(a[(NR-1)%n+1])}' file sometext futhertext text somemore etc