When you’re at a Unix terminal and your terminal goes screwy, try typing “stty sane” to reset it. Handy!
stty sane
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Tag Archives: linux
tr
I learned about the ‘tr’ Unix command today. It’s for translating text in streams. The particular example was:
echo | tr '012' '001'
And I didn’t really understand what that did, but now I do. Basically the ‘echo’ part will echo a new line character, which is octal 012. Then tr will read its input stream and read that new line. It then has a rule to translate 012 (new line) to 001 (Ctrl+A), which it does. So basically it’s just a way of getting a Ctrl+A character in a stream. If you use Ctrl+A as your regular expression delimiter you’re unlikely to have a collision in the expression itself.
Environment Variables and Secure Programming for Linux
I read the Environment Variables section of Secure Programming for Linux and Unix HOWTO and learned about the IFS environment variable.
I also read CS 15-392 Secure Programming – Environment Variables.
The IFS environment variable is the “internal field separator” and it is typically space, tab, new line. I.e. white space used to separate fields. So in bash you can delete the IFR variable and it will default to ” \t\n” or you can set it explicitly to that value. So that explains why I found a script that unset the IFR variable — it’s a secure programming practice.
I’ve set up a new file server
I’ve been having some fun over the last day or two looking over all my old files. I’ve got files that go back as far as 1999 in my archives. I’ve found my old blog database and associated files, so I hope to get that back up again soon, and I found some old code that I’ve been looking for (I don’t want to have to write it again!).
So my new file server has 6TB of storage as 3 x 2TB partitions. I can fit all my data in 1.3TB of space, so I’m planning to have one file share, and then a backup of that onto another partition. I have 10,174,633 files in my archive folder, and many more in my media, download and home folders. I might publish some more stats once du -s has finished processing. :)
I’m running Ubuntu 10.04 LTS Server as my file server. I tried to setup the Desktop version but it wouldn’t play nice with my nVidia graphics card.
dirent.h
I’m doing some Linux C++ programming, and I’m doing the dev work on Windows, so I figured I’d have a go at compiling in Visual Studio (I’m running VS2008). One problem I had was that there was no dirent.h header file, but I found one.