Consider this snippet:
echo '7 a
3 c
3 b
2 first
2 second
2 third
2 fourth
2 fifth
9 d
2 sixth
' | sort -n -k 1
It gives an output of:
2 fifth
2 first
2 fourth
2 second
2 sixth
2 third
3 b
3 c
7 a
9 d
While the list is correctly ordered numerically keyed by first character, also for those values which are contiguous and equal, the original order has been shuffled. I would like to obtain:
2 first
2 second
2 third
2 fourth
2 fifth
2 sixth
3 c
3 b
7 a
9 d
Is this possible to do with sort? If not, what would be the easiest way to achieve this kind of sorting using shell tools?
Just add the -s (stable sort) flag, this disables last-resort comparison
echo '7 a
3 c
3 b
2 first
2 second
2 third
2 fourth
2 fifth
9 d
2 sixth
' | sort -k 1,1n -s
2 first
2 second
2 third
2 fourth
2 fifth
2 sixth
3 c
3 b
7 a
9 d