Bind SSHD to ipv4

When you all of sudden run into "No X11 DISPLAY" when trying to forward X11 over ssh. Ask yourself if you recently disabled ipv6 on the sshd server. If the answer is yes then try the following to make sshd bind only to ipv4.

Add "AddressFamily inet" to /etc/ssh/sshd_config. Then restart sshd.

Mount Windows Filesystem From Linux

How to mount a windows drive through the administrative share from linux. $ sudo mount -t cifs <windows hostname>/<drive>$  -o username=<user>,password=<pwd>,domain=<domain>  /<mount-point>

Share VBox Folder With Linux

First you need to create a Transient or Machine Folder within VirtualBox "Settings > Shared Folders" for the specific VM you would like to enable shared folders for. Make sure to remember the name of the folder, for our example we'll use the name "temp" pointing to "c:\temp". Next, from within the linux OS command line you would create a mount point and mount it as so $ mkdir /mnt/temp $ sudo mount -t vboxsf temp /mnt/temp Once you are done sharing files you can unmount the folder by doing the following: $ sudo umount /mnt/temp

Get IP on Linux

Today I needed to get the ip address as part of script to configure the "/etc/hosts" file. The command to get the IP is a one line command:

$ ifconfig | grep 'inet addr:' | grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1 }'

Thats all it takes to get the IP address(es) of the current interfaces excluding the loop back adapter. Other variants of *nix and windows may require different commands.

Get rpm and dependencies

On RHEL/Centos you need to install "yum-utils" first. $ sudo yum install yum-utils Then you can download an rpm and its depdencies by doing the following: $ sudo yumdownloader --resolve <rpm name> Then, you can transport them to another computer with a USB drive.

Add RSpec

I need to add the rspec gem to my ruby project. How do I do that?  Can I do this from the command line or do I need to open a file? Looks like I need to open my "gemspec" file and add the line: spec.add_development_dependency "rspec" Then, I can install the gem through bundler from the command line: $ bundle install Next, add a directory structure and spec files. [project]/spec/spec_helper.rb # Reference code in ../lib [project]/spec/[gem name]/actual_spec.rb # Relative reference to ../spec_helper.rb Now you should be able to run rspec from the command line: $ bundle exec rspec actual_spec.rb