Sunday 05 February 2006 at 10:55 pm
MD5 hashes are not only good for digital signatures, they're good for making sure that files you've downloaded weren't corrupted. However, a directory full of files can prove problematic because you have to cat the text file of MD5 sums to expect, run md5sum against a file, compare it visually.. it can get annoying afte a short period of time. Thankfully, the GNU implementation of the md5sum utility has the option
--check, which lets you pass a text file of lines ("MD5 <filename> = <MD5 sum>") to the utility. It will automatically compute an MD5 sum of each file in the text file and compare it to the expected value in the file, printing out an message for each file that passes.
Whenever your web browser hangs for a while because it's waiting for a file download to start, you'll inevitably jump over to another window to do something else. Just when you start typing in that other window the dialog box for the filename to save to will pop up with a suggested filename and grab focus, so whatever commands you were typing will replace that filename. This is great for losing files because they're named with snippets of text, such as
rm -rf /tmp/sourcecode.
They're also a cast-iron bitch to remove or rename after the fact.
More under the cut...
Sunday 05 February 2006 at 10:52 pm
In this modern age of viruses, worms, and script kiddies, there are manufacturers who will, in fact, pitch a fit if you try to install a security patch of any kind. There are also network-accessible appliances out there that
require the use of telnet and eschew
SSH for secure administrative connections.
It's a good idea to assign values to variables as close to where they'll be used as possible so that you don't lose track of what they are called or what they're supposed to do.
Write the simplest regular expression that'll do the job that you can, so you'll spend far, far less time debugging later.
More under the cut...
Sunday 05 February 2006 at 10:49 pm
Cosplay: Proving that when there is a will, there is a way to construct damn near anything.
When installing
Perl modules by hand, be sure that you have lots of coffee handy. Not only can it take a bloody long time to compile everything, but running
make test (and you'd
better run
make test to be sure you're not hosing your installed copy of
Perl) can take an amazing amount of time.
Sure, you can automagickally install stuff from CPAN (
perl -MCPAN -e shell) but if you need to go through a proxy server, you're screwed. You'd be better off, in this event, to install everything from CPAN on a machine that doesn't have to deal with a proxy server, copy the source tarballs over to the destination machine en masse, and compile everything by hand.
More under the cut...
Sunday 05 February 2006 at 10:46 pm
When using
sed (Stream EDitor) in a shell script to match or strip out certain strings of characters, keep in mind that character usage in the
regular expressions doesn't work the same. For example, running the following command manually on the command line works properly, but does not do what you'd expect inside a shell script:
sed s/\<\\/td\>//
That command is supposed to find all of the </td> tags in an HTML document and substitute for them nothing (i.e., erasing them from the file). It works properly if run manually, but inside a shellscript you're not getting a true backslash to escape the forward slash. To put it another way, as far as sed is concerned, you're giving it the following command, which won't do what you want it to:
s/\</td\>//
That puts an extra forward slash in the regular expression, which causes it to
ABEND. The actual command that you should put in the shell script is this:
sed s/\<<\\\\/td\>//
More under the cut...
Sunday 05 February 2006 at 10:43 pm
Whenever you put your headphones on at work, someone will want to talk to you within thirty seconds, necessitating removal of said headphones.
Never try the Jedi Mind Trick on police officers. Their will is too strong.
When your account officer at the bank looks at the interest rate on your checking account and remarks "That's pitiful," you know something's wrong.
More under the cut...
Sunday 05 February 2006 at 10:40 pm
Stuff to always bring with you if you'll be staying in a hotel:
- One or two bars of soap. The travel-size bars the hotels give you aren't good for more than one shower.
- Full-sized bottles of shampoo and conditioner. The travel-size bottles the hotels give you aren't enough for a single person with a full head of hair.
- Washcloths or scrubbies. The ones they give you don't get you clean, but work well as coasters.
- Locks for luggage. Don't trust the housecleaning staff to not go through your things (some of my stuff was stolen at Tekkoshocon 2005).
- A roll of duct tape. You never know when you'll have to fix something.
- Wireless network card and ethernet cable for your laptop. More and more hotels are providing free net.access for guests.
More under the cut...
