Bash: sort text file by last field value

Question

I have a text file containing ~300k rows. Each row has a varying number of comma-delimited fields, the last of which is guaranteed numerical. I want to sort the file by this last numerical field. I can't do:

sort -t, -n -k 2 file.in > file.out 

as the number of fields in each row is not constant. I think sed, awk maybe the answer, but not sure how. E.g:

awk -F, '{print $NF}' file.in 

gives me the last column value, but how to use this to sort the file?

Answer 1

Use awk to put the numeric key up front. $NF is the last field of the current record. Sort. Use sed to remove the duplicate key.

awk -F, '{ print $NF, $0 }' yourfile | sort -n -k1 | sed 's/^[0-9][0-9]* //' 

Answer 2

vim file.in -c '%sort n /.*,\zs/' -c 'saveas file.out' -c 'q'