On Wed, Mar 25, 2020 at 01:17:19PM -0500, Eric Blake wrote: > On 3/25/20 12:37 PM, Richard Ipsum wrote: [snip] > > See the difference? In the first case, sort is doing its default > case-insensitive comparison of the entire line (because you passed -f but > not -k), AND a stability comparison of the byte values of the entire line > (as shown by the two ____ lines per input). But in the second case, when > you add -s, the stability comparison is omitted. The two lines are indeed > different when the stability comparison is performed, explaining why -c > choked when -s is absent. Or put another way, -f affects only -k, including > the implied -k1 when you don't specify anything, and not -s. So now that we > know that, let's return to your example:
I'm trying to understand this relative to POSIX, which makes no mention of stability as far as I can see (and there is no -s in POSIX). POSIX says that -f should override the default ordering rules. I don't understand why the last-resort comparison is required when -c is in use, since we're not sorting with -c, just checking if the input is already sorted? Put another way should -c imply -s ? Thanks, Richard
