ksh built in commands
Sometimes it can be confusing to know where to find more info about built in shell commands.
man cd
...
cd - ATAPI and SCSI CD-ROM driver
man 1 cd
man: No entry for cd in the manual.
A suitable alias is there to help
type cd
cd is a shell builtin
type type
type is an alias for 'whence -v'
So you can find info about cd in ksh manual. Search the long man page using /cd <ENTER>
man ksh
...
cd [-LP] old new
The string new is substituted for old in the current directory,
and the shell attempts to change to the new directory.