BigSmoke

Smokes your problems, coughs fresh air.

Month: September 2008

Change ext3’s reserved block count and gain Gigabytes

September 15, 2008 /

Wiebe was looking over my shoulder while I was running df to check the disk space that was still available on my Lenovo ThinkPad: 

# df -h /dev/sda2
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              90G   79G  7.3G  92% /

He noticed that there was a huge gap between the total space (79 used + 7.3 available = 88.3) and the actual size of the file system. According to him this was due to the reserved block count, which is set to five percent by default in ext2 and ext3 file systems—clearly a legacy from a time where disks were smaller.

# dumpe2fs /dev/sda2|grep -i 'reserved block count'
dumpe2fs 1.40.8 (13-Mar-2008)
Reserved block count:     1196559

# dumpe2fs /dev/sda2|grep 'Block count'
dumpe2fs 1.40.8 (13-Mar-2008)
Block count:              23931180

# echo 'scale = 2; 1196559 / 23931180'|bc
.05

I changed the reserved block count with tune2fs:

# tune2fs -m 1 /dev/sda2
tune2fs 1.40.8 (13-Mar-2008)
Setting reserved blocks percentage to 1% (239311 blocks)

# dumpe2fs /dev/sda2|grep -i 'reserved block count'
dumpe2fs 1.40.8 (13-Mar-2008)
Reserved block count:     239311
# df -h /dev/sda2
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              90G   79G   11G  88% /

Now, the reserved blocks take up roughly 934 MiB; I’ve freed 3.7 GiB with this little file system tweak. 🙂

Update 14 nov 2010: I finally fixed two errors in my final calculations spotted by Den. He noticed that the numbers (700 MiB and 13 GiB) were wrong. Thanks, Den!

png2ico: converting favicons to Windows’ ICO format

September 4, 2008 /

Even though, strictly speaking, I should be using favicons in anything but Windows’ ICO format and refer to them from a <link>-tag at any location other than /favicon.ico, I sometimes like to help Microsoft break the web by putting an ICO file at the location that they reserved for it (/favicon.ico).

My tool of choice for converting PNG’s to ICO is Matthias Benkmann’s png2ico. To generate an ICO file with this program, you just need to feed it one or more PNG files. The possibility to include differently sized PNG files can help you make sure that the icon will steal look good when being dragged to the desktop or some other non-miniature context.

$ png2ico
png2ico 2002-12-08  (c) Matthias S. Benkmann
USAGE: png2ico icofile [--colors ] pngfile1 [pngfile2 ...]

Here’s an actual example which creates an ICO file from a single PNG file:

$ file favicon.png 
favicon.png: PNG image data, 16 x 16, 8-bit/color RGBA, non-interlaced
$ png2ico favicon.ico favicon.png

Of course, we should discourage browsers from doing useless requests for /favicon.ico by actually telling them when it is available: (as if…)

<link type="image/x-icon" rel="shortcut icon" href="/favicon.ico" />

Now we can go back to pretending that: No, we’re not encouraging the practice of link squatting. We just happen to have put our favicon in that location.

For the less tech savvy

Update 30 sep 2012: There’s a free online service to convert PNG to ICO: www.pngtoico.com. It doesn’t require you to do anything complicated (like installing Unix stuff). Just pick your original and get the converted image. 🙂

Decoding djvu files on the command line

September 1, 2008 /

So, you have djvu files on a remote machine that you have SSH access to, and the local machine you’re working on doesn’t have djvu tools. What do you do? Simple, use ddjvu to decode the djvu files to images.

And that’s all. I kept forgetting the name of the tool, so, now I won’t anymore…

© 2026 BigSmoke

Theme by Anders Noren — Up ↑