When you are first learning
, especially if you are an intrepid experimenter,
there are two other
commands that are handy for getting out of
any mess that you might create.
What if you want to wipe out all of the edits you have made in
a session and then return to the original file? The command:
returns you to the last saved version of the file, so you can start over.
Suppose, however, that you want to wipe out your edits and then
quits the file you're editing and returns you to the UNIX prompt.
With both of these commands, you lose all edits made in the
buffer since the last time you saved the file.
normally won't let you throw away your edits. The
exclamation point added to the
to override this prohibition, performing the operation even
though the buffer has been modified.
You try to write your file, but you get one of the following messages:
exists - use w!
File is read only
to overwrite the existing file, or type
to save the edited version in a new file.
You want to write a file, but you don't have write permission for
it. You get the message "Permission denied."
to write out the buffer into a new file.
If you have write permission for the directory, you can use
to replace the original version with your copy of it.
If you don't have write permission for the directory,
write out the buffer to a directory in which you do have write
permission (such as your home directory).
You try to write your file, but you get a message telling you that
the file system is full.
to delete a (large) unneeded file and
free some space.
command with an exclamation point gives you
access to UNIX.)
to see whether there's any space on another file system.
If there is, choose a directory on that file system and write your
file to it with
is the UNIX command to check a
The system puts you into open mode and tells you that the
file system is full.
The disk with
's temporary files is filled up.
to see whether there are any files you can remove to
gain some disk space.
If there are, create a temporary UNIX shell from which you can remove files or issue
other UNIX commands.
You can create a shell by typing
to terminate the shell and return to
a Berkeley UNIX system, you can simply type
and return to the UNIX prompt; type
to return to
Once you've freed up some space, write your file with
You try to write your file, but you get a message telling you that your
disk quota has been reached.
Try to force the system to save your buffer with the
If that doesn't work, look for some files to remove.
if you are using a Berkeley system) to move out of
) to return to
when you're done.
Then write your file with
The only way to learn
is to practice.
You now know enough to create a new file and to return to the
Create a file called
, insert some text, and then
save and quit the file.
Open a file called practice in the current directory
any text you like
Return to command mode
, saving edits