unix sorting, with primary and secondary keys

Question

I would like to sort a file on more fields. A sample tab separated file is:

a   1   1.0
b   2   0.1
c   3   0.3
a   4   0.001
c   5   0.5
a   6   0.01
b   7          


        

Answer 1

The manual shows some examples.

In accordance with zseder's comment, this works:

sort -t"" -k1,1d -k3,3g

Tab should theoretically work also like this sort -t"\t".

If none of the above work to delimit by tab, this is an ugly workaround:

TAB=`echo -e "\t"`
sort -t"$TAB"