Files order in the command line

I want to load together pwads,mods,codes etc., which in some cases have conflicts between them.
What order should I type them in the command line?

If some resources conflict, then the resources in the later loaded wads will override the resources in the earlier loaded wads. As for which particular wads to load first, it depends on which particular wads they are.

For example, I want to load: Flashback to Hell(FTH666.WAD), Smooth Doom, Samsara and nashmove.pk3 (code)

Mike800 said:

For example, I want to load: Flashback to Hell(FTH666.WAD), Smooth Doom, Samsara and nashmove.pk3 (code)

I think you have to choose between Smooth Doom and Samsara, they change too much.

Or try the monsters-only version of Smooth Doom, instead of the normal version.

Yes, almost all gameplay mods tend to be incompatible with each other (with the exception of weapon-only-changing mods often being compatible with monster-only-changing mods), though they're compatible with most mapsets (except some of those introducing their own gameplay modifications), as that's their purpose. Generally, gameplay mods should be loaded after mapsets, and more complex/important gameplay mods after less complex ones or those less important to you.

IIRC, I once loaded a pwad, a mod and a code,(in this particular order) but the code didn't work properly.

If by "code" you mean some ACS-based mod, it's possible, as ACS-based mods usually don't collide with resources of other wads, but they may depend on some default behavior that other gameplay mods might be changing by other means than by ACS.

Is there a fix for this issue?

My general rule of thumb is to make sure that map WADs are loaded first, and then gameplay mods. This way, the gameplay mod doesn't randomly have its resources altered by any unusual resources in the map WAD, especially in regards to sound effects.

Mike800 said:

Is there a fix for this issue?

If you've tried all possible orders to load the mods in, and none works correctly, the mods are apparently incompatible. "Fixing it" would require modifying at least one of the two mods specially with the other one's traits in mind. The amount of work (and knowledge) needed to do so depends on the particular case, and if both mods are complex, it may be extreme. If you have no experience with DECORATE and ACS or you're not willing to spend days on meddling with mods before playing them, you may as well forget about the option. That said, you might try to look for possible other versions of the mods you're using that would be more compatible with other mods, sometimes somebody already made them. But the usual solution is to give up using one or more of the mods to become able to play the others properly.

scifista42 said:

"Fixing it" would require modifying at least one of the two mods specially with the other one's traits in mind. The amount of work (and knowledge) needed to do so depends on the particular case, and if both mods are complex, it may be extreme.

In this particular case, I want to modify mods with a 2 kb code-nashmove.pk3, which consists of only 5 files. How do I do it?

Mike800 said:

How do I do it?

1. Learn both DECORATE and ACS if you don't know them yet.
2. Study the contents of your mods to figure out why does any of them prevent another one from working properly.
3. Modify the mod which didn't work with traits of the other mod in mind.

If that sounds too hard/tedious to you - I can tell you that it sounds too hard/tedious to me as well, even though I already do know both ACS and DECORATE. But I don't have any more specific answer to the question of how to do it.