Lack of disk space on Mac - check out whats happening in /private/var/folders

MacOS-free-disk-space

TL; DR - running out of disk space on your Mac, try a safe reboot to 
properly clear /var/folders.

I noticed I was just about out of disk space on my Mac earlier, and digging 
around noticed that /var/folders was huge. 

cd /var/folders;  sudo du -shc
125G	.
125G  total

I suspected com.apple.IconServices among others

sudo find /var/folders -name com.apple.IconServices -exec du -shc {} +
636M    /var/folders/05/x288dhqn2ksbc05r61ymthzw0000gq/C/com.apple.IconServices
642M    /var/folders/0f/0lr8_ls52qd8ggm3nm5ktwfr0000gq/C/com.apple.IconServices
636M    /var/folders/0l/2l_yh0tx3j9_f08_82rfd4mh0000gq/C/com.apple.IconServices
....
642M    /var/folders/zx/709fdx3x2zj6wmc19w4cxgqr0000gq/C/com.apple.IconServices
120K    /var/folders/zz/zyxvpxvq6csfxvn_n00000bh00002w/C/com.apple.IconServices
 84G    total
 
The easiest (and safest) way to clear /var/folders is to do a safe reboot. 
Power off your mac, power back on, hold down shift once you hear the startup 
beep and a progress bar will appear. Grab a coffee, let MacOS do its thing and 
then reboot back to normal mode.

$ cd /var/folders; sudo du -shc
836M	.
836M	total