How to order several options of a command (ls)?

Question

Why doesn't ls behave the same after exchanging the order of options -l and -f?

$ ls -l -f
0821131236.jpg   0823130821.jpg

$ ls -f -l
total 33176
-rw-rw-r--  1 t    t    364186 Jan  6 16:06 0821131236.jpg
-rw-rw-r--  1 t    t    170003 Jan  6 16:06 0823130821.jpg

What advice should I follow when running ls or other utilities/commands with several options?

Answer 1

This is a documented behavior.

From info ls:

-f:

 Primarily, like `-U'--do not sort; list the files in whatever
 order they are stored in the directory.  But also enable `-a' (list
 all files) and disable `-l', `--color', and `-s' (if they were
 specified before the `-f').

What you should use totally depends on what you need.

Answer 2

In a typical software, the arguments are usually processed in order, so a latter option gets to overwrite the former ones if they are in conflict, but still enabled to be used together. But this is just a general rule of thumb. You have to check the documentation of the particular software you intend to use and try it out for yourself.