Sometimes I find it useful to switch to hex mode when editing a file in vi. The command for switching is not very obvious so thought I’d share…
So, open a file in vi as usual, hit escape and type:
:%!xxd to switch into hex mode
And when your done hit escape again and type:
:%!xxd -r to exit from hex mode.
Okay, so this isn’t actaully switching to vi’s ‘hex mode’; vi doesn’t have one. What the above actually does is to stream vi’s buffer through the external program ‘xxd’.
Very nice!, vi is the gratest editor ever made.
Thanks mate.
Thanks for the tip
Thanks, it is very useful.
I found a problem using the suggested vi command (:%!xxd). I opened a network dump file with vi and then switched on hexmode. To my suprise the bytes seemed wrong. I downloaded another hexeditor called ghex to verify that it I was right.
Used vi version:
VIM – Vi IMproved 7.2
You can check if your own vi shows the hexcode incorrectly by generation your own network dump (cap) and then open it. The first 4 byte should problably be D4 C3 B2 A1, but vi is showing C3 94 C3 83
Try adding the following to /etc/vim/vimrc.local, and you’ll get keyboard shortcuts for switching back and forth (F8 and F7).
” Switch to hex-editor
noremap :%!xxd
” Switch back
noremap :%!xxd -r
(Repost, it ate my code. Preview would be a good feature).
Try adding the following to /etc/vim/vimrc.local, and you’ll get keyboard shortcuts for switching back and forth (F8 and F7).
\" Switch to hex-editor
noremap <F8> :%!xxd<CR>
\" Switch back
noremap <F7> :%!xxd -r<CR>
Try adding the following to /etc/vim/vimrc.local, and you’ll get keyboard shortcuts for switching back and forth (F8 and F7).
” Switch to hex-editor
noremap <F8> :%!xxd<CR>
” Switch back
noremap <F7> :%!xxd -r<CR>
Thanks. That’s pretty rad. Just what I was looking for.
I wanted a hex editor and had one the whole time.
Thanks a ton for the tip!
Great tip, I’m linking to it
helped me a lot, thanks!
how to go to offset with it ?
This is kind of misleading. That isn’t actually invoking any sort of ‘hex editor’ functionality of vi, it’s just streaming the file through the external application ‘xxd’. It’s certainly a nice tip, but if you want to understand what’s actually happening and how you can better control the conversion, the place to look is the xxd man page.
This isn’t a “hex mode”. :! is Vim’s filter syntax. :%!xxd selects the range of the entire buffer, filters it through the external xxd program and replaces each line with the resulting output (though xxd appears to be part of the vim package on my distro, not a standard Linux command). You could accomplish the same by launching Vim with a bash command like “vim <(xxd filename)" assuming xxd is located in your $PATH. It should be nicely highlighted nicely if ft=xxd.
Lousy vim
Tried to save the file and it wrote the readable hex-code instead.
The reversion is required!
Hi Steven,
if you have accidentally saved the hex-code of your file, so you can revert to your original code using the command
$:> xxd -r your_file_name
this will do the reverse operation of xxd and convert the hex-code into the binary code.
Hi,
if you have accidentally overwritten your file with the hex code then you can revert to the original file by using the command:
xxd -r your_file_name
This will do the reverse conversion from hex code to binary code.
Thanks a Lot, very useful
this is extremely useful. I was about to try teach myself how to use yet another command line text editor, so this saved me some time.
Great tip! Thanks for sharing
xxd is an awesome program, and vi(m) is another one. [snip of insulting and obnoxious rant]
So, if you ever read that, I don’t care if you remove this comment, AS LONG AS YOU CLEAR THINGS UP IN YOUR POST.
[more snipping], here is a more correct version of it :
” Sometimes I find it useful to switch to hex mode when editing a file in vi. vi doesn’t have such a feature, but it has the capability of using an external program as a ‘filter’ (meaning that the input (stdin) of the program is taken from vi buffer, which is later replaced by its output (stdout)). xxd is the binary used to transform one’s binary into hexadecimal and vice versa. The vi command for using it as a filter is not very obvious so thought I’d share…
So, open a file in vi as usual, hit escape and type:
:%!xxd
to switch into hex mode
And when your done hit escape again and type:
:%!xxd -r
to exit from hex mode.
As you can easily figure it out, ‘:[address-range] ! external-command-name’ is vi’s command for filtering. % as an address-range means : everything in the buffer. See http://www.softpanorama.org/Editors/Vimorama/vim_piping.shtml for further information.”
Thanks for giving me a nudge and reminding me to update my post. It was quite overdue. I know that most people are only looking for the quick tip and don’t care how it works, but you’re right, the explanation was misleading.
Hey.
Thanks for not suppressing (entirely) the comment. With more research I found that vi’s “hexadecimal mode” is a sort of urban legend, and, sadly, doesn’t only belong to your blog. It would be harsh to ask EVERY blog editor to correct their version (which on the top of that are all slightly different). So, I give up. The world gonna stay the stinking heap of lies it is.
On the other hand your edits made me smile (I’m not being sarcastic by the way), and I don’t think my original text was that insulting. But I do agree, it wasn’t that nice either and it’s your blog.
Thanksfor the info (and the commenters), I hope xxd works as well standalone as it does with vi.
When you are creating a new binary file, you most probably want to set some flags before saving:
:set noeol
:set binary
Otherwise vi will append a newline (0x0a) at the end of the file.
This is only an issue when creating a new binary file. When you open an existing binary file vi automatically sets these flags for you.
Janos
http://www.bashoneliners.com/
It gets better. Vim can do all the xxd filtering back and forth automatically if you add the following in your .vimrc:
augroup Binary
au!
au BufReadPre *.bin let &bin=1
au BufReadPost *.bin if &bin | %!xxd
au BufReadPost *.bin set ft=xxd | endif
au BufWritePre *.bin if &bin | %!xxd -r
au BufWritePre *.bin endif
au BufWritePost *.bin if &bin | %!xxd
au BufWritePost *.bin set nomod | endif
augroup END
You also get nice syntax highlighting (if you have syntax highlighting correctly setup in general).
Change that “*.bin” to whatever comma-separated list of extension(s) you find yourself wanting to edit.
This tip actually comes from :help hex-editing
http://vimdoc.sourceforge.net/htmldoc/tips.html#hex-editing
Cheers, Janos
http://www.bashoneliners.com/
Thanks a lot for the info and the corrections guys. I love Linux, but even after many years of use there are still new useful commands/features I find.
Thank you very much for this hint!
I use GVim, and the command works like a charm!
You need to invoke vi with the “-b” switch (binary), or else risk messing up the resulting binary:
vi -b
Add the following to the end of your /etc/vimrc or equivalent:-
” The following maps the F8 key to toggle between hex and binary (while also setting the
” noeol and binary flags, so if you :write your file, vim doesn’t perform unwanted conversions.
noremap <F8> :call HexMe()<CR>
let $in_hex=0
function HexMe()
set binary
set noeol
if $in_hex>0
:%!xxd -r
let $in_hex=0
else
:%!xxd
let $in_hex=1
endif
endfunction
Thanks, this is what I was looking for .. this way I can’t filter 2 times by mistake