Details

This week, we're continuing our Linux Terminal 101 series with redirection of standard errors into files.

Download HD Download MP4

This week, I am redirecting standard errors. First, to understand standard errors, we need to know that the linux shell refers to standard input, output, and error as 0, 1, and 2 respectively as their 'file descriptors'. So, by using the number 2, we can redirect an error like this: la -l /bin/usr (bin/usr does not exist which is why we'll get an error) 2> ls-error.txt. That number 2 tells the shell to redirect errors to ls-error.txt.

Now say you want to redirect both standard outputs and errors to the same file. Do this: ls -l /bin/usr > ls-output.txt 2>&1. This moves the outputs to the ls-output.txt then redirects errors to 1 (which is the file descriptor for outputs. Remember to put the error redirection at the end of the command, or it won't work. That's the old way. There is a new way to redirect both to the same file. Try this out: ls -l /bin/usr &> ls-output.txt. Less typing = good!

Do you hate error messages? Me too! So lets just throw them away. I don't want to see it on my screen, so I can type this command that probably sounds familiar to some and is quite the joke to others: ls -l /bin/usr 2> /dev/null. /dev/null is a universally known concept in Unix that tosses all those bits into a bucket and does absolutely nothing with them.

Next time on HakTip, let's have some fun with cats! Tell me about your ideas in the comments or email me tips@hak5.org with your thoughts. And be sure to check out our sister show, Hak5 for more great stuff just like this. I'll be there, reminding you to trust your technolust.

Leave a Reply

Your email address will not be published. Required fields are marked *

*