mongorestore Too many open files
ulimit can be set in the same terminal by 
ulimit -n 10000; 

You can change the value in /etc/security/limit.conf file by 
nofiles to 10000 #line

the maximum no of files can be opened in any linux/unix system is 64000. be sure of this no. If your restoring of database size is huge then try to make them smaller pieces like create the database and then try to restore one collection or few collections at a time. If you have memory limit like 4/8 GB of RAM then it is better to restore collection by collection instead of whole database.

As you are trying mongorestore from local system I believe this is not a production system and not a serious business, if my assumption is correct please try to restore few collections at a time and see if you still face the same issue.   

Thanks @wylliam-judd for sharing the solution; I didn't face this issue as I used linux as a remote host and accessed from putty and in the same window; anyway I'm adding your solution to help others 

The solution was to run ulimit -n 64000 in the console running mongod rather than in the console running mongorestore. Though I did run it in both consoles to be safe, and I can't be sure whether the ulimit in the mongorestore console was necessary or not. I also attempted many other solutions in these months, and I can't be entirely sure that none of them had an impact, but the difference that finally mattered was running ulimit in the console running mongod.