Would a monk with the tavern brawler feat have improvised weapons count as monk weapons? It states in the monk martial arts feature that:


  At 1st level, your practice of martial arts gives you mastery of combat styles that use unarmed strikes and monk weapons, which are short swords and any simple melee weapons that don’t have the two-handed or heavy property.


Now for the Tavern Brawler feat it states that:


  You are proficient with improvised weapons and unarmed strikes.


And the rules for improvised weapons are:


  In many cases, an improvised weapon is similar to an actual weapon and can be treated as such. For example, a table leg is akin to a club. At the DM’s option, a character proficient with a weapon can use a similar object as if it were that weapon and use his or her proficiency bonus. An object that bears no resemblance to a weapon deals 1d4 damage. 


If the improvised weapon does not resemble a weapon, is simple, and is not heavy or two-handed, could a monk replace the d4 dice? For example if the monk is level 6 and has a unarmed attack of a d6, with a d6 dice instead?


Question: Kernel compilation and free space
Answer: Are you compiling as root?  I don't know if the free space reported by df takes into account the typical 5% superuser reservation.

Also it could be the kernel hasn't flushed the disk cache yet.

It is also possible your /usr is mounted on a separate partition.  This is quite likely if you took the defaults during your Ubuntu install (unless something has changed since the last time I used Ubuntu...)

If you run out of disk space and the compilation fails, free up some disk space and resume the compilation by issuing the make command again.

Bad idea to let / run out of space.  I would try to address that ASAP.