http://tldp.org/LDP/abs/html/
The command line application on the Kindle is Busybox Ash, a simplified version of Bash (which is probably on your MacOSx box).
((Yes, you will find my name in that one.))
and also:
http://linuxcommand.org/ **
((untouched by myself))
Copy it where? (as in full pathname of destination).
The Kindle has fixed size partitions, all except user storage is nearly full.
The device is very likely to brick if they are actually filled up.
There needs to be room for the system to survive its file system checks during boot up.
See if you have the 'free' command on the Kindle.
You had better install kTerm the direction you are going in.
No, it is not a 'hack', it is a commonly used PC application ported to the Kindle.
'Hack' is just another four letter word.
** second page, first para: zsh is included with USBnetworking package
** second page, second para: xterm - the kTerm program before being ported to the Kindle.
** Yes, somewhere we have a build of Bash for the Kindles also.