On Linux Mint (Ubuntu) I had installed the Arduino IDE from the repository and that had installed version 1.0.5. Despite setting the permissions on the Arduino USB device, the ‘Serial Port’ option in the IDE menu was greyed out and would not allow for selecting the device – it thus defaulted to using COM1 –… Read more »
Posts By: jonny
Resetting Drained Slurm Node
After barking up the wrong tree for a while I discovered via StackExchange how to reset a Slurm Node reporting as drained. Run the scontrol command then update the node as shown in the following example commands (amend the word jacob here to the name of your node): [root@machine]# scontrol scontrol: update NodeName=jacob State=DOWN Reason=”undraining”… Read more »
MySQL GRANT SELECT on a demo database to all users
I needed to give all students read access to a demo database and did so with: mysql> GRANT SELECT ON gameofthrones.* TO ”@localhost; Query OK, 0 rows affected (0.00 sec) mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.01 sec)
Kerberos Keytab File Creation on Ubuntu
To create a kerberos keytab file on Ubuntu and with the kerberos packages installed (e.g. sudo apt-get install krb5-user ) root@jmcc02:~# ktutil ktutil: addent -password -p myusername@DOMAIN.TLD.COM -k 1 -e RC4-HMAC Password for myusername@DOMAIN.TLD.COM: ktutil: wkt username.keytab ktutil: quit root@jmcc02:~# After completing those steps there should be a keyfile created in the current directory. That… Read more »
Apache: unable to open logs
In the annals of “Everyday is a learning day”. I have an Apache server hosting student websites, and the number of websites grew to over 700 within a day and Apache was complaining with error: unable to open logs It took a little while to narrow down the problem as I assumed there was a… Read more »
Customise the Unity Launcher from Command Line
I am rolling out some Linux desktops, specifically Ubuntu, and I wanted to customize the icons available in the Unity Launcher. I wanted to remove the LibreOffce Calc and Impress icons and the darned ‘Amazon’ one, so: Create a new gschema override file for our customisations: vi /usr/share/glib-2.0/schemas/99_launcher.favorites.gschema.override Add some content (the com.canonical.Unity.gschema.xml file in… Read more »
Create Password Hashes From the Command Line
I wanted to generate a password hash for use in the /etc/shadow file. My local Linux Mint (Ubuntu) Desktop already has mkpasswd available, your distribution may vary. mkpasswd -m SHA-512 This prompts for the password and will generate the hash.
Locating Excessive Inode Usage
The command to list the directories using the most inodes is: find . -printf “%h\n” | cut -d/ -f-2 | sort | uniq -c | sort -rn However, I first needed to narrow down the directory under root that might be causing the problem: df -i showed that the root directory (/) was the problem…. Read more »
Powershell Script to Set Computer Name Based on DNS
This Powershell script will use nslookup to query a DNS Server to get the hostname and use that result to set the computer name. If you use this you will need to amend as necessary including the address of the DNS Server (I have added the Google one here for illustration) and I am filtering… Read more »
CentOS 7 as NAT Gateway for Private Network
The scenario is a small private network connected via a switch and using 192.168.0.* addresses. One of the machines (let’s call it RTR001) on the network has two network interface cards. One with an address on the 192.168.0.* network and another providing wider network (& internet) access on a 123.111.123.* network. This machine (RTR001) will… Read more »
