Re: [PLUG] VI without a swapfile?

[JP Vossen <jp@jpsdomain.org>]

On 02/27/2012 08:57 PM, plug-request@lists.phillylinux.org wrote:
> Date: Mon, 27 Feb 2012 20:02:53 -0500
> From: Jeff Bailey<skydiver38@verizon.net>
[...]
> Without getting into all the gory details, I have a loopback filesystem
> mounted (a file containing a filesystem) which is considered 100% full
> (according to "df").
>
> I need to edit a file on that mount.  "vi" complains about not being
> able to create a swapfile, but allows me to edit.  The problem is that I
> can't save an edited version, even if all I do is delete lines.  I think
> this stems from the fact that vi tries to save a backup copy, and fails
> since there's no room.

Short version: edit elsewhere or use 'ed'.

Long version:
If the changes are non-trivial, I think the "edit elsewhere and cat back 
into place" is the best solution.  In my experience, all the other 
solutions I tried like vi, 'sed -i', 'perl -i' actually wrote elsewhere 
and moved.  The "-i" for "in place" really means "duplicate owner & 
perms."  If you don't believe me, run 'stat' before and after and check 
the inodes.

Having said that, 'ed' should work, if it is actually installed on the 
"minimal" system.  It's required by SUS/POSIX, but depending on how 
formal and minimal the file system is trying to be...  'ed' is even 
scriptable, though that sounds like overkill in this case.  Remember 
that 'ed' is a line editor designed for teletypes, so it's even more 
stone knives and bear claws than 'vi'.  (And I say that with affection, 
since I *like* vi. :)

You will likely need a cheat sheet, see the man page on basically any 
Unix or Linux system installed in the last, oh, 35 years or so...  :-) 
Or start at http://en.wikipedia.org/wiki/Ed_%28text_editor%29.

I used 'ed' for recipe 17.14 Editing a File in Place in the _bash 
Cookbook_ precisely because (in my 'stat' tests at the time) it really 
does overwrite the same file, it's scriptable, and it's always there.

Ha, just for fun I went and looked and I still have 
c:\windows\system32\edlin on XP.  I don't find it on Win7, though you 
can get a FreeDOS version with support for long file names now. 
http://en.wikipedia.org/wiki/Edlin is short and interesting and just 
proves there is *nothing* more permanent than a temporary solution.

Later,
JP
----------------------------|:::======|-------------------------------
JP Vossen, CISSP            |:::======|      http://bashcookbook.com/
My Account, My Opinions     |=========|      http://www.jpsdomain.org/
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