awk: add new column, including header

问题

I have a file that looks like this:

name measurement gender duration
a 1 m 55
b 1 f 54
c 2 m 53
... etc

I want to use awk to add a column, which has the same value for every row, except the first (the header). Let's say I want to add the column new_column with the value 99 for every row, so the output file looks like this:

name measurement gender duration new_column
a 1 m 55 99
b 1 f 54 99
c 2 m 53 99
... etc

This sounds like a job for awk... but I haven't been able to figure out how. Any ideas? Many thanks!

回答1:

$ awk '{s=(NR==1)?"new_column":"99";$0=$0 OFS s}1' file
name measurement gender duration new_column
a 1 m 55 99
b 1 f 54 99
c 2 m 53 99

回答2:

You can use this awkcomand:

awk 'NR==1{$(NF+1)="new column"} NR>1{$(NF+1)="99"}1' file

回答3:

You could golf it like this (assuming you have no empty lines):

awk '$++NF=NR==1?"new_column":99' infile

Output:

name measurement gender duration new_column
a 1 m 55 99
b 1 f 54 99
c 2 m 53 99

来源：https://stackoverflow.com/questions/47220452/awk-add-new-column-including-header