Ubuntu's vi command into edit mode, generally there are six kinds of methods,
1, in vi into edit mode, also called insert mode, general direct press the letter key on the keyboard. A, I, o, specific meaning in the following table:
Insert text after the cursor, a
A, at the end of the line bank inserted into the text.
I insert text before the cursor,
I at the beginning of the line inserted into the text;
O insert new lines under the cursor,
O insert new lines on the cursor;
CTRL + c to exit the edit mode
: q, exit (file no changes)
: q! Exit without saving (file changes)
: wq save and exit