Linux file sort with incomplete columns

Question

I need to sort a file by the first column, if there is a numerical entry, and by the second column when there is none in the first. It looks basically like this:

3 - foo bar
1 1 foo bar
- 5 foo bar
2 2 foo bar
- 4 foo bar

and I need the output then to be

1 1 foo bar
2 2 foo bar
3 - foo bar
- 4 foo bar
- 5 foo bar

Is there any nice way to do that in linux with a single command? Thanks!

Answer 1

在遵循该格式的输出上，您可以只使用基本的sort命令：

sort -k 1,2 foo.txt