I have files with the 2504 individuals of the 1000 genomes project, and I want to filter by population. I did the following for the first population (ACB):

    plink --file all1000gen --keep indACB.txt --make-bed --out all1000genACB
but it gives back the following error:

    Error: Line 1 of --keep file has fewer tokens than expected.
my indACB.txt file looks like this:

    head indACB.txt 
    HG01879
    HG01880
    HG01882
    HG01883
    HG01885
    HG01886
    HG01889
    HG01890
    HG01894
    HG01896
which I made (por each population, using grep) from the population information file that's available in the 1000 genomes page, which has a two times the individual ID (first two columns) and one with the population name, as shown:

    head indpop2.txt
    HG00096 HG00096 GBR
    HG00097 HG00097 GBR
    HG00099 HG00099 GBR
    HG00100 HG00100 GBR
    HG00101 HG00101 GBR
    HG00102 HG00102 GBR
    HG00103 HG00103 GBR
    HG00105 HG00105 GBR
    HG00106 HG00106 GBR
    HG00107 HG00107 GBR
I think there's a problem with my --keep file, but I'm not sure what's the wanted structure of the txt file.

I also tried greping ACB individuals from indpop2.txt , so the new indACB.txt file looks like this:

    head indACB2.txt 
    HG01879 HG01879 ACB
    HG01880 HG01880 ACB
    HG01882 HG01882 ACB
    HG01883 HG01883 ACB
    HG01885 HG01885 ACB
    HG01886 HG01886 ACB
    HG01889 HG01889 ACB
    HG01890 HG01890 ACB
    HG01894 HG01894 ACB
    HG01896 HG01896 ACB
But it yields the following error:

    plink --file allconcat39 --keep indACB2.txt --make-bed --out allconcat43ACB

    Error: No people remaining after --keep.
from https://www.cog-genomics.org/plink/1.9/filter

> --keep accepts a space/tab-delimited text file with family IDs in the first column and within-family IDs in the second column, and removes
> all unlisted samples from the current analysis.

So like this:

    HG00096 HG00096
    HG00097 HG00097
    HG00099 HG00099
    HG00100 HG00100
    HG00101 HG00101
    HG00102 HG00102
    HG00103 HG00103
    HG00105 HG00105
    HG00106 HG00106
    HG00107 HG00107