ex: 0602-101 Out of memory saving lines for undo.
vi editor may not display your file well, especially the file is large. For example:
[oracle@primary01 oracle]$ vi nohup.out
...
ex: 0602-101 Out of memory saving lines for undo.
To solve the error, we need to make vi editor to know that we want to raise the line limit of the displayed file.
[oracle@primary01 oracle]$ export EXINIT='set ll=10000000'
EXINIT is a environment variable that vi editor reads it first before open the file. Once it opens the file, it will execute the command in the variable. In this case, we set the line limit to 10,000,000 lines, ll stands for line limits of the editor.