free: Implement almost all functions of the free commands

[Krysztal112233]

Aims

This pull request aims to implement almost all function about free command.

And also fix wron arguments and flags.

TODO

• Fix -h flag's function
• free: implement the different size display #18
• Implement -h --human flag
  • Automatically scale
  • Scaled shortest three digit unit
• free: implement --line  #21

[sylvestre]

great start but
please don't implement everything into a single PR

[Krysztal112233]

great start but please don't implement everything into a single PR

Okay, next I'll split it into multiple PR.

So what should this PR do next?

[Krysztal112233]

I have a question about using if instead of match:

Sometimes match looks cleaner and more direct, so why not use match? Because match won't be optimized by branch prediction?

[sylvestre]

Sometimes match looks cleaner and more direct, so why not use match?

Because match is used when we have several diverse values.
For such operations, the de facto standard is to use if instead.
it is also for consistency with coreutils

Because match won't be optimized by branch prediction?

I hope that, between Rust and LLVM, it will generate the same code.

[sylvestre]

https://godbolt.org/z/Ec3aedhWG confirms that is generate the same code

[Krysztal112233]

https://godbolt.org/z/Ec3aedhWG confirms that is generate the same code

I got it

[Krysztal112233]

completes almost all the most often flags for the free command now

[sylvestre]

Sorry, i only realize thi now. Could you please add tests in
https://github.com/uutils/procps/blob/main/tests/by-util/test_free.rs
thanks