View Only Headers with Curl

When working with curl, it can give lots of excellent and detailed information, but sometimes it is too much! Today I'm fiddling with the caching headers on a client's application, so I'm only interested in seeing the headers and not the body of the response. Making a HEAD request changes the output I get, so I really do want to GET and then only see the headers.

Handily, when you use the -v verbose flag with curl, it sends the output to stdout as usual, but the extra information including the headers goes to stderr. This means that I can therefore view the headers only throwing away stdout completely:

curl -v -s http://awesome-site.com 1> /dev/null

(you need the -s to stop curl from "helpfully" printing progress bars as well)

Colourless Git Output

I teach git and often have issues with bad projectors where you can't see the colours. Recently I had a setup where even white on black was more or less invisible, but using black text on a white background worked okay. There's lots of documentation on how to turn on colours in git but not so much about how to turn them off.

Try putting the following into .git/config:

[color]
    branch = false
    diff = false
    interactive = false
    status = false

I had expected to be able to set color.ui to false but that didn't seem to make much difference, so I now use the settings above. I thought I'd drop it here in case anyone else is looking for the same thing.

Copy/Pasting and Vim

I'm a vim user and I somehow completely missed this excellent feature until much more recently than I care to admit! Usually vim has its own clipboard, but it doesn't share with the operating system. You will need a vim-gtk install, this isn't available in really basic vim (I'm a little unclear exactly on the dependencies).

To paste between vim and something else, use the + (plus) buffer in vim. It contains the contents of your system clipboard, and you can also write to it. If you're not already using buffers in vim, then you should probably read the excellent documentation but for a very quick start:

  • To copy something into the buffer, select it in visual mode and type "+y
  • To paste from the buffer, type "+P

I had no idea how I'd missed this really fundamental trick, so I thought I'd share!

Quick Switch Between Git Branches

Today's little-known git feature (or maybe everyone knows but me? I only found this a few months ago) is for quickly switching between branches. Usually I would switch branches with:

git checkout [branchname]

However if you switch from one branch to another and want to switch back again (this happens when I'm reviewing changes and wondering if a bug is present on master as well), then you can do so by just doing:

git checkout -

Just a little timesaver in case it's useful to anyone else - I know I've been using it quite a bit!

Printing PDF Bookmarks List

I work with PDF a lot, and it bothers me that I can see an outline view when I open the document, but I don't seem to be able to grab just that view. My presentations are mostly PDF and the titles and section headings show up nicely. Today I figured out how to get an outline view, so I'm putting that information here while I remember how to do it!

I used a tool called pdftk which is excellent, I've used it before for doing various other PDF-related things. To grab metadata such as bookmarks, use the dump-data command, like this:

pdftk myfile.pdf dump_data | grep BookmarkTitle > outline.txt

The above line takes all the bookmarks from the PDF (this was a slide deck created using powerdot and LaTeX, the section and slide titles nest appropriately), and outputs a bunch of information about the document and the various PDFs. The grep command just gets the lines containing "BookmarkTitle", then the whole thing gets written to a file. I cleaned that up and now I have the outline of my course, so I can add timings, notes for the exercises and so on.