‘uname -a’ gives you some useful info about kernel version, but if you’re looking for the specific version of Ubuntu that you have installed, try ‘cat /etc/issue’ which should include a line with the exact Ubuntu version.
Expanding virtual disk size for a Fedora guest on VirtualBox
First, while the virtual machine is down, resize the disk image:
vboxmanage modifyhd vdi_disk_image_name.vdi --resize new_size_in_mb
Now boot the image and logon. If you’re not using LVM, I think to resize regular partitions it’s as simple as starting gparted, and then just drag the size of the partition to take up the new unformatted space. If you are using LVM, then do the following:
sudo lvm
List physical volumes with pvs, find the one containing the logical volume that you want to resize, and then use pvresize:
pvresize --setphysicalvolumesize xxG /dev/name
To show volume groups:
vgs
To show logical volumes:
lvs
To expand a logical volume to use the newly added space:
lvextend -L +sizeG vg_groupname/lv_volumename
where size is the new size in GB.
ruby gem error: “ERROR: While executing gem … (ConcurrencyError)”
On Windows 7 running ‘gem install [gem name]” I was getting this cryptic error:
ERROR: While executing gem … (ConcurrencyError)
Detected invalid array contents due to unsynchronized modifications with concurrent users
The only post I found that mentions this exact error was in the comments for this post about Neo4j on Ruby, and specifically getting this error with jruby 1.6.0.-RC2. I was using 1.6.0-RC1. I downloaded the latest version (1.6.7.2) and replaced my older version, and that fixed it.
Managing SSH keys on Heroku
Heroku uses Git for your code repo, and therefore uses SSH to talk to the remote server. If you’re already using an SSH keypair for another repo or elsewhere, you may have to explicitly manage which of your key’s you want to use to access Heroku.
To list your current keys you’ve shared with Heroku:
heroku keys
To add a new key – run this from your ~/.ssh/ dir:
heroku keys:add keyfilename (e.g. rsa_id.pub)
If you get this error:
Fingerprint already exists. Please use one SSH key per Heroku account
… it’s because you’ve already used this SSH key with another account.