Sort unix alphabetically then numerically, not working as I intended

Question

Sorry if this is a duplicate question, but I could not find the answer that I am looking for here or in the documentation.

I have a file that looks like the following:

chr2_oligo1234  700 750
chr2_oligo1236  750 800
chr1_oligo1 50  100
chr1_oligo256   150 200
chr1_oligo6 3500    3550
chr4_oligo95    50  100
chr5_oligo1 50  100
chr4_oligo4 150 200

The desired output looks like:

chr1_oligo1 50  100
chr1_oligo256   150 200
chr1_oligo6 3500    3550
chr2_oligo1234  700 750
chr2_oligo1236  750 800
chr4_oligo95    50  100
chr4_oligo4 150 200
chr5_oligo1 50  100

The pattern at the start (e.g. chr#_oligo#) only matters in terms of the chr#, meaning that all chr1 should be first, then chr2, then chr3, etc., but I would like to sort those substrings numerically in groups as shown by the desired output above. So, I would like to know how to sort alphabetically in the case of the first column, and then keeping that order (chr1->chrN), sort each chunk of data numerically.

I apologize if my wording is not the best for this issue or if it is a duplicate. Trying

sort -k1,1 -nk2

does properly sort numerically, but does not keep the first sort intact (jumbles up the first column and places together all lines with columns 2 and 3 being like:

50   100

I am using Mac OS X.

EDIT: I want changed some of the examples in the first column to show more of what I'm looking for. gsort -V worked great if the name in the first column is in numerical order, but in my data set, it isn't always the case.

I would like to essentially sort each subgroup (in this case, chr1, chr2, etc) by column 2 iteratively. I realize this can be easily done by doing a grep for each and then sorting it on column 2, but I would like to know if sort or another unix command could accomplish this alone.

Answer 1

sort -k1,1 -nk2 is the same as sort -k1,1 -n -k2, same as sort -n -k1,1 -k2, as in the numerical sorting is turned on globally, for all the keys.

To sort the 2^nd key only numerically, you need to add n to that sort key description as in:

sort -k1,1 -k2n

Or:

sort -k1,1 -k2,2n

With n and with the default field separator 2 is the same as 2,2 though. 2 would be the part of the line starting from the second field, but when interpreted as a number, that's the same as the second field alone (2,2).

Here, you could also sort numerically on the number that is after chr and then alphabetically on the rest of the first field and then numerically on the second field with:

sort -k1.4n -k1,1 -k2n

Answer 2

sorting alphabetically on the 1st field, and numerically on the 2nd gives (in your output, -- chr4_oligo95 is before ch4_oligo4)

sort -k1,1 -k2n,2n file 
chr1_oligo1 50  100
chr1_oligo256   150 200
chr1_oligo6 3500    3550
chr2_oligo1234  700 750
chr2_oligo1236  750 800
chr4_oligo4 150 200
chr4_oligo95    50  100
chr5_oligo1 50  100