History function
Unfortunately, there is no built in history functionality in SQL*PLUS that would allow to go back a number of commands issued in SQL*PLUS.

However, there is gqlplus (on sourceforge) that enhances sql plus with a history functionality. With cygwin (as apparently also with linux and possibly other Unix variants),
rlwrap can also be used.

SQL*Plus is then called like $ rlwrap sqlplus user/password@sid. rlwrap is a wrapper around readline. On HP-UX, one can call sql*plus from ied (something like ied sqlplus usr/pass@srv There seems also to be an ied equivalent in perl: feb.tar.gz

On windows, the function key F7 gets a list of previously executed commands. Also, if a letter is already entered, it gets the list with commands starting with that letter. Also the arrow keys work.
Note: This works only with the command line sqlplus (sqlplus.exe), not with the gui version (sqlplusw.exe). On emacs, M-x sql-oracle does the trick. On 9i, iSQL Plus seems capable of exactly this.