Celeborn

Running Powershell commands on a set of files

2024-06-23T20:53:00.000-07:00

PS Microsoft.PowerShell.Core\FileSystem:: C:\PhD\Datasets\Astrometry\Set-146> Get-ChildItem -File | ForEach-Object { file2pdfpsedit.exe $_.FullName --args xr }

Tmux : Create multiple windows to ssh to several servers

2022-11-16T15:54:00.006-08:00

#!/usr/local/bin/zsh

SESSION="Maintenance-X"

tmux new -s "${SESSION}" -d
tmux rename-window -t "${SESSION}.0" Main
tmux new-window -d -t "${SESSION}" -n Server1
tmux new-window -d -t "${SESSION}" -n Server2
tmux new-window -d -t "${SESSION}" -n Server3

# Run ssh command in each window
tmux send-keys -t "${SESSION}:1" 'ssh server1.mydomain' Enter
tmux send-keys -t "${SESSION}:2" 'ssh server2.mydomain' Enter
tmux send-keys -t "${SESSION}:3" 'ssh server3.mydomain' Enter

# To run command in a pane within a window, use:
# tmux send-keys -t "${SESSION}:1.<pane-position>" 'ssh server1' Enter
# tmux send-keys -t "${SESSION}:1.top" 'ssh server1' Enter

tmux attach-session -d -t "$SESSION"

Creating a user service on Linux

2021-10-17T04:26:00.002-07:00

This is an example of running a local python script as a user service.

Most of this information was found here.

Service location:

/home/user/.config/systemd/servicename.service

Service definition/contents of servicename.service

[Unit]
Description=Metriful User Service

[Service]
ExecStart=/usr/bin/python3 /home/user/script.py
Restart=on-failure

[Install]
WantedBy=default.target

Reload Systemd so it can find the new service

systemctl --user daemon-reload

Enable Service with

systemctl --user enable servicename.service

Let Service run even when all user sessions have expired

loginctl enable-linger <user>

ZSH First time run

2021-10-11T19:10:00.003-07:00

These are the commands to re-run ZSH first time setup.

autoload -Uz zsh-newuser-install
zsh-newuser-install -f

Grafana is pretty awesome

2020-03-27T17:31:00.003-07:00

It was so easy to setup. Definitely needs more time spent with it. But I have dashboards, alerting, and push notification thus far. Pretty sweet.

#monitoring #server #graphs

Replacing a failed hard drive in an (encrypted) ZFS Pool on FreeNAS

2017-04-19T22:05:00.001-07:00

Disk Failure Email Alert

Device: /dev/ada5, failed to read SMART Attribute Data
Device: /dev/ada5, not capable of SMART self-check
Device: /dev/ada5, Read SMART Self-Test Log Failed
The volume tank (ZFS) state is DEGRADED: One or more devices could not be opened. Sufficient replicas exist for the pool to continue functioning in a degraded state.
Device: /dev/ada5, Read SMART Error Log Failed

Disk went to UNAVAIL on FreeNAS. It was a complete disk failure where the drive would not even turn on.

Checking status of zfs pools:
[..]

  pool: tank
 state: DEGRADED
status: One or more devices could not be opened.  Sufficient replicas exist for
 the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
   see: http://illumos.org/msg/ZFS-8000-2Q
  scan: scrub repaired 0 in 3h22m with 0 errors on Sat Mar 11 15:55:33 2017
config:

 NAME                                                STATE     READ WRITE CKSUM
 tank                                                DEGRADED     0     0     0
   raidz1-0                                          DEGRADED     0     0     0
     gptid/2dc7c53c-2b99-11e6-94d8-0015177adaa2.eli  ONLINE       0     0     0
     gptid/2e7247c8-2b99-11e6-94d8-0015177adaa2.eli  ONLINE       0     0     0
     gptid/2f1f7b49-2b99-11e6-94d8-0015177adaa2.eli  ONLINE       0     0     0
     9773863262585734395                             UNAVAIL      0     0     0  was /dev/gptid/2fa84005-2b99-11e6-94d8-0015177adaa2.eli
     gptid/306d3755-2b99-11e6-94d8-0015177adaa2.eli  ONLINE       0     0     0

errors: No known data errors

Here's how to replace the failed disk:

Offline the disk if you can by going to Storage > Volumes > Select your pool (e.g. tank) > Volume Status (on the status bar at the bottom). I could not do this since the disk was already unavailable and hence offline
NOTE the disk's name, like ada5xx
Next, navigate to the Storage > View Disks and jot down the disk's serial number. You will need this to physically identify the disk later.
Shutdown your computer
Physically remove the disk and replace it with a new one.
Boot up your machine
Go back to Storage > Volumes > Select your pool (e.g. tank) > Volume Status
Select the defective disk's slot and click on Replace
If it's an encrypted pool, enter your passphrase as well
The resilvering process should start

For encrypted pools, once resilvering is completed do the following to avoid losing the pool on the next reboot. Go to Storage > Volumes > Select your pool containing the new disk

Re-key your pool's encryption passphrase
Re-create a passphrase
Download your key
Add a recovery key.

For more detailed information, refer to the FreeNAS documentation.

You can watch the pool rebuilding (resilvering) either on the GUI or on the CLI:

[root@freenas] ~# zpool status tank
pool: tank
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
        continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Wed Apr 19 21:42:55 2017
        49.1G scanned out of 5.89T at 301M/s, 5h39m to go
        9.79G resilvered, 0.81% done
config:

        NAME                                                STATE     READ WRITE CKSUM
        tank                                                ONLINE       0     0     0
          raidz1-0                                          ONLINE       0     0     0
            gptid/2dc7c53c-2b99-11e6-94d8-0015177adaa2.eli ONLINE       0     0     0
            gptid/2e7247c8-2b99-11e6-94d8-0015177adaa2.eli ONLINE       0     0     0
            gptid/2f1f7b49-2b99-11e6-94d8-0015177adaa2.eli ONLINE       0     0     0
            gptid/c3e3e9d1-2583-11e7-8b27-0015177adaa2.eli ONLINE       0     0     0 (resilvering)
            gptid/306d3755-2b99-11e6-94d8-0015177adaa2.eli ONLINE       0     0     0

errors: No known data errors

Excellent read on cloud management

2013-04-29T09:52:00.001-07:00

PCWorld: 21 tips for supercharging your cloud storage. http://goo.gl/mag/pSGrcK5

[Halo] Forerunner Timeline as I understand it

2012-12-17T05:42:00.000-08:00

So far, this is how I picture the events to have taken place during the Human-Forerunner and Forerunner-Flood Wars

Human-Forerunner War
Ur-Didact defeats the Humans and devolves them
Discovery of the Flood by the Forerunners
Brief Forerunner-Flood War
Commissioning of Halos to eradicate the Flood should they emerge again

Ur-Didact opposes to this for his belief in the Mantle and eventually exiled on Erde-Tyrene

Bornstellar discovers Ur-Didact's Cryptum and wakes him
The two travel to various scarred Worlds and Ur-Didact bestows his memories and knowledge to Bornstellar via a Brevet Mutation
They are found by Master Builder Faber who exiles Ur-Didact to a Flood invested planet
Bornstellar is returned to Forerunner territory and becomes the new Didact
Forerunner capital attacked by Mendicant Bias and Faber executed due to War Crimes
Bornstellar finds Mendicant's installation (Halo 7), commandeers it to obtain the Composer

[Unknown Events]
Flood threat arises again
Ur-Didact returns and prepares for battle

Uses human population on Halos to compose an army of Prometheans

The Librarian seriously abhors this act and imprisons the Ur-Didact on Requiem
The Librarian completes Indexing of Sentient Species
[Unknown Events .. but include implantation of Genesong to John-117's ancestors, possibly with an imprint of Forthencho (wild wild guess since he was the greatest threat to the Ur-Didact)]

(Presumably) Bornstellar activates the Halo Array to cleanse the Galaxy

[Rant] Thanks HTC

2012-08-16T22:13:00.000-07:00

Thanks for the update HTC. It made it much easier to decide whether I should buy a One XL. I am now the proud owner of a Galaxy Nexus. After using HTC devices since the Nexus One, I'm afraid to say its time to break-up. Loved my DHD for the past years - it shall now reside proudly on a plynth. Seeing how you have listened to your loyal fanbase recently, my next phones are definitely going to be Nexuses (unless Google decides to award you the contract, in which case, I shall stick with the other players in the market). Thanks for the ride though.

________________________________________________________________________________

My rant is about HTC not releasing an update to the all-so-good Desire HD after telling customers since early 2012 that the device would indeed be upgraded to Ice Cream Sandwich or version 4.0 (ICS). http ://blog.htc.com /2012/03/ics /

The fact remains that the device is capable of running ICS. http ://news.softpedia.com /news/HTC-Desire-HD-Gets-Android-4-0-4-ICS-Update-Unofficial-286715.shtml

So, if you are planning to buy an HTC phone; think again. Although HTC used to be very attentive to customers, they have been very uncooperative on this matter even though a petition was sent through. They should atleast have made an ICS version available without their Sense UI or provide (power-) users with the option to choose whether they want to upgrade or not.

The minute I switched on my Galaxy Nexus, I was provided the option to upgrade to version 4.1 Jelly Bean of Android. I could not be any happier about my decision to drop buying an HTC One XL; which is a great phone as per the reviews but with such support from HTC, the phone will be obsolete by the next update to Android.

The Galaxy Nexus on the other hand will receive the next update of Android since even a Nexus S (predecessor to the Galaxy Nexus) obtained an upgrade to 4.1 (not just 4.0). The Nexus S was released around the same time as the HTC Desire HD with the latter being more powerful specs-wise!!!

UPDATE:
18 Aug: XDA-devs have officially done what HTC could not! Hallelujah!

www.engadget.com/2012/08/17/custom-rom-brings-ics-to-desire-hd/

Weather codes

2011-10-29T05:09:00.001-07:00

Melbourne: asxx0075
Sydney: asxx0112

AOL weather search seems to have the codes necessary for widgets.

My Matrix Moment

2011-05-02T20:44:00.000-07:00

I filmed this while at ACMI on 1st May 2011.

Configuring OpenVPN on FreeBSD [Quick Guide]

2011-03-18T20:09:00.000-07:00

[Note: This post is a work in progress.]

pkg_add -r openvpn
rehash

mkdir -p /usr/local/etc/openvpn
cd /usr/local/etc/openvpn
touch openvpn.conf

cp -R /usr/local/share/doc/openvpn/easy-rsa .

cd easy-rsa/2.0/

[Edit the vars file to reflect your details. This will save you the trouble of having to type your organisation's details every time you generate a certificate. You may also need to change your shell to sh to execute the scripts. I also had to do a chmod +x * in that directory.]

./clean-all
./vars
./build-ca

[Generate Server Key named server1]
./build-key-server server1

[Generate Keys for clients]
./build-key hpserver
./build-key acerlaptop

[Generate Diffie-Hellman keys]
./build-dh

#The following keys have been copied from /usr/local/etc/openvpn/easy-rsa/2.0/keys

ca /usr/local/etc/openvpn/keys/ca.crt
cert /usr/local/etc/openvpn/keys/server.crt
key /usr/local/etc/openvpn/keys/server.key
dh /usr/local/etc/openvpn/keys/dh1024.pem

Now, edit openvpn.conf (on the server-end) as follows. Substitute IP addresses as required.

[OpenVPN Server Config]
#Configuration of OpenVPN Server

port 1194
proto tcp
dev tun

ca keys/ca.crt
cert keys/server.crt
key keys/server.key

dh keys/dh1024.pem

server 10.0.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt

client-config-dir ccd #Client specific settings, e.g. Fixed IP Addresses
client-to-client #Allow clients to communicate with each other

push "route 192.168.0.0 255.255.0.0"

keepalive 60 120

comp-lzo
persist-key
persist-tun

status open-status.log
verb 3

Copy the generated client keys to /etc/openvpn/. You will need to copy, for example, acerlaptop.crt, acerlaptop.key and ca.crt and mentioned them in openvpn.conf on the client as follows.

[OpenVPN Client Config]
#Configuration of OpenVPN Client

client
dev tun
proto tcp

remote openvpn.dyndns.org 1194 #public ip address and port of vpn server

nobind
persist-key
persist-tun

#client certificates
ca ca.crt
cert acerlaptop.crt
key acerlaptop.key
ns-cert-type server
comp-lzo
verb 3

[Auto-start openvpn]
Add the following in /etc/rc.conf on the server.

openvpn_enable="YES"

If not already present, also add the following knob in /etc/rc.conf to allow the server to route between your LAN and VPN subnets.

gateway_enable="YES"

Note: Some documentation propose adding if_tun_load="YES" to /boot/loader.conf. I found that is not necessary. Openvpn will start the required device drivers automatically. You can try adding it, if openvpn fails to start or dynamically start it at a prompt by issuing kldload if_tun.

---

The OpenVPN documentation provides more in depth explanation. It can be viewed at : http://openvpn.net/index.php/open-source/documentation/howto.html.

Using FreeNAS 8.0 as a Bridge

2010-12-29T02:20:00.000-08:00

I have installed and tested this on FreeNAS 8.0 Beta

My FreeNAS server and one workstation are in the same room and I needed a way to connect them to the LAN to allow for fast file transfers between all computers in my network.

Since I lacked a switch, I needed to convert FreeNAS into a bridging device. It was just a matter of installing a spare NIC into the FreeNAS server and doing the following:

Make my CF card readable (you might skip this step if you installed FreeNAS on a mechanical Hard drive).

mount -t ufs -w /dev/ufs/FreeNASs1a /

Insert a FreeBSD 8.0 disk into your cd-rom drive and copy the files as shown:

mkdir /mnt/cdrom
Mount cdrom: mount -t cd9660 /dev/acd0 /mnt/cdrom/

Copy files across:

cp /mnt/cdrom/boot/kernel/if_bridge.ko /boot/kernel/
cp /mnt/cdrom/boot/kernel/bridgestp.ko /boot/kernel/

ee /boot/loader.conf

Add the following line:

if_bridge_load="YES"

Save and exit

Restart the server with "reboot"

Create the bridge and add interfaces:

ifconfig bridge create
ifconfig bridge addm em0 addm em1
ifconfig em0 up
ifconfig em1 ip

dhclient bridge0 (or ifconfig bridge0 inet 192.168.xx.xx netmask 255.255.255.0)

The name of your interfaces might vary. Check with ifconfig.

Note: You can start the bridge automatically at startup. Refer to the FreeBSD Handbook Chapter 31.5 to see how its done.

P.S. You may do this on FreeNAS 7.x as well. You just need to get FreeBSD 7.x's bridge modules for that kernel. They can obtained from http://download.altstu.ru/FreeBSD/releases/i386/7.2-RELEASE/boot/kernel/ or from a FreeBSD 7.x iso image.

Merry Christmas and Happy New Year

2010-12-24T16:10:00.001-08:00

Greetings All,

I would like to seize this opportunity to wish you all a most Merry Christmas and very Happy New Year.

I pray that the New Year brings you bleesed joy, prosperity and success.

Have a wonderful celebration...

With much festive spirit,

Atwin.

Installing Compiz Fusion on Fedora

2010-08-09T09:06:00.000-07:00

Execute the following as root in a terminal.

yum install -y ccsm emerald-themes compizconfig-backend-gconf fusion-icon-gtk
emerald compiz-fusion compiz-fusion-gnome libcompizconfig compiz-gnome compiz-bcop
compiz compizconfig-python compiz-fusion-extras compiz-fusion-extras-gnome

Entering the BIOS Screen of an HP Proliant

2010-08-09T07:49:00.000-07:00

I recently salvaged an HP Proliant Server from the trash (I know!!). It was in a fully functioning order, sporting 1 GB of RAM and a 2.6 GHz Pentium IV processor. It also had an Adaptec RAID controller for the hot swap module.

The problem I faced with the machine was when it boots up, the Adaptec controller displays its own boot-up screen - hence closing the default screen. I have never worked on an HP machine before so I had no idea how to get into the BIOS setup to configure the boot options.

I managed to stall the computer with a bootable USB drive and found what the keys were.

So, if you are stuck in the same dilemma I faced, these keys could come in handy.

F8 - Boot Menu
F10 - Setup Menu
F12 - Network Boot
ESC - Summary and Boot Progress

I am happy to say that this machine is now a dedicated NAS for my home network. :D (I also tried pfSense on it but NAS seem to be a more valuable duty for it - too powerful for routing.)

Solving SSH problem in Fedora

2010-07-05T09:05:00.001-07:00

I have been asked many a times why SSH does not work on Fedora. The simple answer is SSH works. You just need to "unblock" it. The SSH port (22) is blocked by default in Fedora's firewall as a security measure. Go to System -> Administration -> Firewall and sign in as root. Check the box to allow SSH connections and Enable.

SSH should now work.

Installing Essential Software for Fedora

2010-07-05T08:57:00.000-07:00

I recently came across a very handy utility which installs a lot of small but much needed extras for Fedora.

EasyLife for Fedora allows users to setup Flash, Java and a range of codecs and tools to play just about any multimedia file. It also has options to set the sudo functionality for normal users.

The utility can be downloaded from http://easylifeproject.org/.

Install it as root and you choose what features you want to enable. Its as easy as that.

TI-83 Program to calculate Modulus (Remainder)

2010-06-14T03:04:00.000-07:00

Insert into PRGM Editor in TI Calculator

PROGRAM:MOD
:"MODULUS"
:ClrHome
:Prompt A,B
:fPart(A/B)*B --> C
:Disp C
:Pause
:ClrHome

Google Wallpapers?

2010-06-04T08:20:00.001-07:00

It's interesting to see Google borrowing features from Microsoft's Bing - like adding a wallpaper to the Google homepage. Check the story on Softpedia here.

Add a wallpaper to your Google homepage here.

Fedora 13 is out

2010-05-25T07:38:00.000-07:00

Fedora 13 is finally out after 2 weeks (or so!) of delay. It looks great - feature wise. I haven't had time to try it yet, but a review will come as soon as I find some time to test it.

Download it at http://fedoraproject.org/en/get-fedora

Fedora 13 Goddard

2010-05-05T00:11:00.000-07:00

Fedora 13 "Goddard" is due is 14 days. After the renewed disappointment that was Ubuntu 10.04, I can't wait to get Fedora 13 up and running. Fedora 12 is running full-time on both my servers and on my laptop - uptime of more than 5 months (on the server). Hehe :D

Go for Goddard!

Removing old packages from YUM cache

2010-03-13T06:14:00.000-08:00

Running multiple Fedora machines means that I need to update them regularly to keep them in proper running conditions. Being a user in Australia, updating each and every machine puts a load on both my bandwidth and wallet since I pay per GB downloaded.

The simple solution is to enable YUM to keep the downloaded cache and tell all the machines to download the updates from that one machine. The downside of this method is that updates get acculmulated and hence puts a strain on hard disk space as old and new packages are collected.

I needed a way to clean-up the cache and keep only current updates.

The simple way to do it is to use a wonderful utility called Tidy RPM Cache. Its a python script written to recursively scan packages and remove the old ones. For Example if you have three versions of the same package (e.g. Wireshark 1.2.01, 1.2.02 and 1.2.03), Tidy RPM Cache, will only keep the latest one, i.e. Wireshark 1.2.03.

All you have to do is execute the script by pointing it to the directory where your cache is stored. The command is illustrated below. It will scan and clean all the repositories from which you have downloaded packages. Rest assured, you will be prompted whether or not you want to clear the packages once the scan is complete.

[UpdateServer Desktop]$ ./tidy-rpm-cache.py --dir /var/cache/yum/i386/12/

Tidy RPM Cache can be downloaded from freshmeat. Just click on TAR/GZ in the Links section.

Making Latex Work on Fedora 12

2010-01-10T17:02:00.000-08:00

Although, TeX packages can be easily installed via the Add/Remove software, I find it easier to use the command-line specially when you need to install the tex packages.

Just issue the following commands as root to get everything working. Some packages might be redundant but they do get all the aspects of compiling tex documents and their bib files working.

yum - y install tetex-latex
yum - y install texlive
yum - y install tetex-IEEEtran

After installing these packages, you can compile your documents to pdf easily using pdflatex documentname.tex and bibtex bibliography.aux and there you have it.

Have a great One... ;)

2009-12-27T01:22:00.001-08:00

Hello All,

Hope you had a great year and looking ahead for a bright beginning on the next.

Wish you all a very Merry Christmas and a Wonderful New Year 2010.

All the best,

Atwin

Windows Live: Friends get your Flickr, Yelp, and Digg updates when they e-mail you.