What are those files under /var/preserver/Exaa*** ?

These are left over files after a vi session has exited unexpectedly.

$ $ ls -ltr /var/preserve total 156032 -rw------- 1 slist staff 163840 Dec 21 10:45 Exaaa29510 -rw------- 1 slist staff 163840 Dec 21 10:45 Exaaa24238 -rw------- 1 slist staff 196608 Jan 15 18:39 Exaaa24142 -rw------- 1 slist staff 196608 Jan 15 18:39 Exaaa24140 -rw------- 1 slist staff 66584576 Mar 21 14:57 Exaaa66134 -rw------- 1 slist staff 163840 May 13 21:26 Exaaa96366

You may recover the file via “-r” option from vi editor. 

You can get the file name by grepping the first line.
For example, it has the checkapp.sh from the grepping.

When we use the "-r" option, it will search for any file named checkapp.sh from this /var/preserve directory and recover from it, and when you save it, it will be saved from the current directory or you may specify where to save it.

Once it was saved, the temp file will be removed from /var/preserve directory.

$ vi -r checkapp.sh