25 Feb 2005 edp   » (Observer)

mount: only root can do that

Why can't a non-root user do this?

$ dd if=/dev/zero of=img bs=1024k count=1
$ mke2fs -F img
$ mkdir mnt
$ mount -t ext2 -o loop img mnt

That's (IIUC) the standard way to create an initial ram disk for the linux kernel (as documented in eg its Documentation/initrd.txt).

mkcramfs OTOH doesn't require root privileges; any user can run that program to produce a cramfs image from a directory of its contents.

(But the existence of that tool seems to be a result of the fact that cramfs as a filesystem is readonly, so the above method doesn't work -- you can't create any content in the empty filesystem, because it's readonly -- so they were forced to make a separate tool. I'm not aware of corresponding tools for other filesystems. It's too bad the general method above doesn't work for non-root users. It seems unfortunate that just "mounting" a file to see what's packaged up in it -- that's what a filesystem image is, it's basically just like a ".tar.gz" file isn't it? -- why should that be a security risk?)

two-column xterm (and emacs)

Sometimes "top" output is more lines than fit in an xterm on my screen. But I have width enough for another xterm next to it. I'd like a "two-column" xterm so that the second xterm is treated as a vertical extension of the first one.

I'd also like the same thing in Emacs, where I split the screen down the middle (C-x 3) but the right half is a second column extending the buffer on the left half.

Googling "two-column xterm" came up empty.

(Actually I'm running gnome-terminal, not xterm. But varying the search terms doesn't seem to help.)

I wonder about Emacs. Someone has probably implemented what I want for Emacs, right?! Hmm. Looking at "apropos column" results ... "2C-two-columns" sounded promising but I wasn't able to get it to do anything useful. Reading some more docs I see it's meant for editing files with two columns of text. But I just want to display (and scroll and edit) a regular "single column" text file (buffer, really) using *more* than one column, continuing the text from the bottom of one column at the top of the next column (and so on, with three or more columns.)

Hmm... If I had the two-column xterm (gnome-terminal, whatever) presumably I could *run* Emacs in it and it would Just Work and I'd have my two-column Emacs display. But window-splitting would be kinda weird... Hmm...

UPDATE: C-x 3 M-x follow-mode does exactly what I want! Found it by surfing emacswiki.org a bit... Oh and I see AlanShutko pointed out the same thing; thanks!


ABC news: Writing in The New York Times in 1973, Christopher Lehmann-Haupt worried Thompson might someday "lapse into good taste." "That would be a shame, for while he doesn't see America as Grandma Moses depicted it, or the way they painted it for us in civics class, he does in his own mad way betray a profound democratic concern for the polity," he wrote. "And in its own mad way, it's damned refreshing."

Latest blog entries     Older blog entries

New Advogato Features

New HTML Parser: The long-awaited libxml2 based HTML parser code is live. It needs further work but already handles most markup better than the original parser.

Keep up with the latest Advogato features by reading the Advogato status blog.

If you're a C programmer with some spare time, take a look at the mod_virgule project page and help us with one of the tasks on the ToDo list!