sync only one folder on linux

i just happened to find this old bash script i wrote under ~/Dropbox/.dropbox.cache/old_files/

Because it was found under /old_files/, it is probably not the best version, so use at your own risk!  Since it does not delete files, only does dropbox exclude operations, it might be safe.  This was written maybe a decade ago.  

Looks like it would give an error because a folder does not exist in the readlink call.  mkdir -p ${T} before looping might be necessary. 

The intent is to automate adding a parent folder of the deeply nested targeted folder folder you want to download. 

While excluding all other folders brought in when a parent folder is added. 

I should have a newer version in my old bitbucket files or github or sf, but will take a while to find it.

#!/bin/bash
echo Problems:
echo dropbox exclude remove ~/Dropbox/DontExcludeMe/MeNeither
echo does nothing unless its parent directory is first included first.
echo When the parent directory is included, it brings in all its subfolders and files. 
echo I smell a tree walk of some kind here.  
echo Is bash capable of binary trees?

echo Would have to include all the ancestors that do not exist yet
echo and then add the child directories one-at-a-time
echo but at the same time, exclude any other directories.  

D=~/Dropbox
T=~/Dropbox/DontExcludeMe/MeNeither   # T for TARGET
#mkdir -p ${T}   # May need to uncomment this to precreate the wanted nested folder.
T2=${T}; 

dropbox exclude remove ${T}  #WONT DO ANYTHING IF PARENT DOES NOT EXIST.
echo ${T2}; 
while [ ${D} != ${T2} ]; do J=$(dirname $(readlink -f ${T2} ));  #readlink CAUSES FAILURE WHEN $T DOES NOT EXIST
	echo readlink CAUSES FAILURE WHEN ${T2} DOES NOT EXIST.  Add code to test for existance of ${T2}.
	echo ${J}; 
	echo "We have to filter for the directory target ${T2}, otherwise we add it right back to be excluded!"
	dropbox exclude remove ${T2}  
	sync   #Give it a little time to come back.  Should loop for it to be back in existence.
	find ${T2} -maxdepth 1 -type d -print0 | egrep -v "^${T2}$" | xargs -0 dropbox exclude add
	T2=$J; 
done;

#find ${T} -maxdepth 1 -type d -print0 | egrep -v "^${T}$" | xargs -0 dropbox exclude add