Redhat linux, file to sort - "aaa":
4;AAA;456
3;BBB;567
2;AAA;123
1;BBB;234
5;AAA;000
sort only by second field - command:
sort -t ";" -k2,2 aaa
output is:
2;AAA;123
4;AAA;456
5;AAA;000
1;BBB;234
3;BBB;567
In my opinion output should be:
4;AAA;456
2;AAA;123
5;AAA;000
3;BBB;567
1;BBB;234
Error in sort?
There could be other reasons, but I'll guess that it is your "opinion", because you think that for records with equal keys, whichever one was first encountered in the file should be first in the output.
That is known as a "stable sort".
Stable sorts can take more work, and in most cases aren't required, so by default the sort command doesn't do it. Hence the results you saw.
It can do it if you want it to though:
$ sort --stable --field-separator=";" --key="2,2" aaa
4;AAA;456
2;AAA;123
5;AAA;000
3;BBB;567
1;BBB;234
