Vi editor very useful text editor on linux systems. Below commands most use commands.
Vi Editor Commands
i > insert
ESC + q! > exit without save
ESC + wq! > exit with save
ESC + w! > only save
/searchtext > search to down
?searchtext < search to up n > next text of search
u > one change undo
U > all changes undo
yy > copy line
p > paste line
shift + insert > paste
shift + G > go last line
dd > delete line