Bash sort using general numeric value on alphanumeric string not returning rows sorted properly

Question

I have a file containing three TAB-separated columns. The 1st column is a number, the second is a sequence of 8 characters followed by 1-3 digits, the 3rd is the same as the 2nd column. Here's a minimum reproducible example:

1       abceefgh10      abceefgh22
1       abceefgh10      abceefgh9
1       abceefgh11      abceefgh10
1       abceefgh13      abceefgh11
1       abceefgh14      abceefgh13
1       abceefgh15      abceefgh14
1       abceefgh17      abceefgh16
-1      abceefgh18      abceefgh17
1       abceefgh19      abceefgh18
-1      abceefgh1       abceefgh2
-1      abceefgh20      abceefgh12
1       abceefgh21      abceefgh19
1       abceefgh22      abceefgh20
-1      abceefgh23      abceefgh21
1       abceefgh24      abceefgh24
1       abceefgh2       abceefgh1
1       abceefgh3       abceefgh3
1       abceefgh5       abceefgh5
1       abceefgh6       abceefgh25
1       abceefgh6       abceefgh6
1       abceefgh7       abceefgh7
-1      abceefgh8       abceefgh3
1       abceefgh9       abceefgh8

This example is what I get when I try to sort the columns with sort -gk2.9.

To the best of my knowledge I should expect to see the second column sorted from 1 to 24, and with increasing numerical value (i.e. 1,2,3,4,... and not 1,10,2,20,..., which would result if using -n).

If I cut the 2nd column and sort it with the same command (cut -f 2 ${file} | sort -gk1.9), I actually get the sorting that I want. Am I getting something obvious wrong?

what about sort -t $'\t' -V -k2, from this answer general numeric sort is for number with exponent — Nahuel Fouilleul
– Nahuel Fouilleul, Commented Jul 12, 2019 at 12:02
Thank you, it worked. As a side-note, it worked also without using the natural version sorting (-V), as long as I specified the field separator using $'\t'. — schmat_90
– schmat_90, Commented Jul 12, 2019 at 12:17
more exactly should be sort -t $'\t' -V -k2,2 to sort only over second column otherwise sorts also over the next columns — Nahuel Fouilleul
– Nahuel Fouilleul, Commented Jul 12, 2019 at 12:46

Adam Sosnowski · Accepted Answer · 2019-07-12 12:52:18Z

3

Using --debug option you can see column selection does not work as expected:

1>abceefgh10>abceefgh9  
         ^ no match for key

specifying separator in accordance with Nahuel's comment works (sort -t $'\t' --debug -gk2.9):

1>abceefgh10>abceefgh9     
          __

edited Jul 12, 2019 at 12:52

answered Jul 12, 2019 at 12:18

Adam Sosnowski

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2 Comments

Nahuel Fouilleul Over a year ago

looking at the manual :

KEYDEF ... If neither -t nor -b is in effect, characters in a field are counted from the beginning of the preceding whitespace.

Adam Sosnowski Over a year ago

Right. Deleted "poor documentation" paragraph.

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