Switched On Tech Design

Tag: ubuntu

  • Ubuntu Server: How to change to the root user

     

    Some guides tell you to enter “su” on Unix systems to get superuser permissions; in Ubuntu, however, this won’t work. As a user with sudo permissions (the user created on install has these) enter the following instead:

     

    sudo su

     

    Enter your account password and voila, you are logged in as root. You can tell when you are logged in as root as your prompt will look like:

     

    root@luna:/home/#

     

    rather than:

     

    tma1@luna:/home$

     

     

    Note the # rather than the $? This indicates that you’re performing actions as the root user. This can be dangerous as you will be able to do things which can wreck your system irreparably, so be careful! To go back to working as your usual user, type:

     

    exit

     

    or hit CTRL+D.

  • Ubuntu Server Benchmarks: Geekbench

     

    This is one of our favourite benchmarks for Ubuntu Server – it’s cross-platform, meaning that it can be ran on Windows, Mac OS X, Ubuntu Desktop, Ubuntu Server and more. You can get the download link from the following site:

     

    http://www.primatelabs.com/geekbench/download/linux/

     

    Currently this works:

     

    wget http://d34wv75roto0rl.cloudfront.net/Geekbench-2.4.2-Linux.tar.gz

     

    Unzip:

     

    gunzip Geekbench-2.4.2-Linux.tar.gz

     

    Untar:

     

    tar -xvf Geekbench-2.4.2-Linux.tar.gz

     

    Change directory to the new files:

     

    cd dist/Geekbench-2.4.2-Linux

     

    If you have a license key, enter it like so:

     

    ./geekbench_x86_64 -r [youremail] [license]

     

    Then run the 64-bit:

     

    ./geekbench_x86_64

     

    If you don’t, use the 32-bit version:

     

    ./geekbench_x86_32

     

    Note! If you haven’t installed the ia32-libs package the 32-bit Geekbench will not work on a 64-bit system! Running the benchmarks will give you output similar to the following – a brief rundown of the system setup followed by the benchmark results as they happen:

     

    System Information
    Operating System      Ubuntu 12.04.2 LTS 3.2.0-38-generic x86_64
    Model                 VMware, Inc. VMware Virtual Platform
    Motherboard           Intel Corporation 440BX Desktop Reference Platform
    Processor             Intel Xeon E5-2630 @ 2.30 GHz
    2 Processors, 6 Cores, 6 Threads
    Processor ID          GenuineIntel Family 6 Model 45 Stepping 7
    L1 Instruction Cache  32.0 KB
    L1 Data Cache         32.0 KB
    L2 Cache              256 KB
    L3 Cache              15.0 MB
    Memory                19.6 GB
    BIOS                  Phoenix Technologies LTD 6.00

    Integer
    Blowfish
    single-threaded scalar   1647 ||||||
    multi-threaded scalar   10574 ||||||||||||||||||||||||||||||||||||||||
    Text Compress
    single-threaded scalar   2485 |||||||||
    multi-threaded scalar   14490 ||||||||||||||||||||||||||||||||||||||||
    Text Decompress
    single-threaded scalar   2980 |||||||||||
    multi-threaded scalar   18177 ||||||||||||||||||||||||||||||||||||||||
    Image Compress
    single-threaded scalar   2208 ||||||||
    multi-threaded scalar   12950 ||||||||||||||||||||||||||||||||||||||||
    Image Decompress
    single-threaded scalar   2733 ||||||||||
    multi-threaded scalar   16503 ||||||||||||||||||||||||||||||||||||||||
    Lua
    single-threaded scalar   4460 |||||||||||||||||
    multi-threaded scalar   26572 ||||||||||||||||||||||||||||||||||||||||

    Floating Point
    Mandelbrot
    single-threaded scalar   2194 ||||||||
    multi-threaded scalar   13365 ||||||||||||||||||||||||||||||||||||||||
    Dot Product
    single-threaded scalar   3558 ||||||||||||||
    multi-threaded scalar   22600 ||||||||||||||||||||||||||||||||||||||||
    single-threaded vector   4130 ||||||||||||||||
    multi-threaded vector   29112 ||||||||||||||||||||||||||||||||||||||||
    LU Decomposition
    single-threaded scalar   2791 |||||||||||
    multi-threaded scalar   16599 ||||||||||||||||||||||||||||||||||||||||
    Primality Test
    single-threaded scalar   6190 ||||||||||||||||||||||||
    multi-threaded scalar   29957 ||||||||||||||||||||||||||||||||||||||||
    Sharpen Image
    single-threaded scalar   5657 ||||||||||||||||||||||
    multi-threaded scalar   34118 ||||||||||||||||||||||||||||||||||||||||
    Blur Image
    single-threaded scalar   2287 |||||||||
    multi-threaded scalar   13782 ||||||||||||||||||||||||||||||||||||||||

    Memory
    Read Sequential
    single-threaded scalar   4657 ||||||||||||||||||
    Write Sequential
    single-threaded scalar   6769 |||||||||||||||||||||||||||
    Stdlib Allocate
    single-threaded scalar   4084 ||||||||||||||||
    Stdlib Write
    single-threaded scalar   1872 |||||||
    Stdlib Copy
    single-threaded scalar   3674 ||||||||||||||

    Stream
    Stream Copy
    single-threaded scalar   5435 |||||||||||||||||||||
    single-threaded vector   7031 ||||||||||||||||||||||||||||
    Stream Scale
    single-threaded scalar   5668 ||||||||||||||||||||||
    single-threaded vector   6441 |||||||||||||||||||||||||
    Stream Add
    single-threaded scalar   5311 |||||||||||||||||||||
    single-threaded vector   7203 ||||||||||||||||||||||||||||
    Stream Triad
    single-threaded scalar   5556 ||||||||||||||||||||||
    single-threaded vector   5082 ||||||||||||||||||||

    Benchmark Summary
    Integer Score              9648 ||||||||||||||||||||||||||||||||||||||
    Floating Point Score      13310 ||||||||||||||||||||||||||||||||||||||||
    Memory Score               4211 ||||||||||||||||
    Stream Score               5965 |||||||||||||||||||||||

    Geekbench Score            9474 |||||||||||||||||||||||||||||||||||||

    Upload results to the Geekbench Browser? [Y/n]

     

     

    If you upload the results, you can add them to a Geekbench account by accessing a web link – such as:

     

    Upload results to the Geekbench Browser? [Y/n]y

    Uploading results to the Geekbench Browser. This could take a minute or two
    depending on the speed of your internet connection.

    Upload succeeded. Visit the following link and view your results online:

    http://browser.primatelabs.com/geekbench2/18911

    Visit the following link and add this result to your profile:

    http://browser.primatelabs.com/geekbench2/claim/18911?key=572432

    root@luna:/home/tma1/geekbench/dist/Geekbench-2.4.2-Linux#

     

    Put the address it gives you into a browser and you will be able to gather results over time to compare systems/virtual machines! Geekbench is one of the best Ubuntu Server benchmarks that we have come across – it provides you with a range of tests which are easy to compare, as well as giving you an overall score figure to give you an idea of how the system performs overall vs. other setups. The fact that it is cross-platform is a great bonus, too, as it means you can test the efficiency and performance of a variety of operating systems on the same hardware/virtual hardware setups – and the results can be very interesting. Highly recommended!

  • Ubuntu Server Benchmarks: Phoronix Test Suite

     

    The Phoronix Test Suite is another option when it comes to benchmarking your Ubuntu Server – this one doesn’t work out-of-the-box and requires you to choose the types of benchmarks you wish to run and install them either individually or as suites of benchmarks. You can download it at the following link currently:

     

    wget http://phoronix-test-suite.com/releases/repo/pts.debian/files/phoronix-test-suite_4.4.1_all.deb

     

    Then:

     

    chmod +x phoronix-test-suite_4.4.1_all.deb

     

    Install like so:

     

    dpkg -i phoronix-test-suite_4.4.1_all.deb

     

    You can run it for the first time with the following:

     

    phoronix-test-suite

     

    You will be shown a page of the package’s terms and conditions and prompted to accept them. To see a list of available benchmarks, run:

     

    phoronix-test-suite list-tests

     

    If you wanted to install the blake2 benchmark as an example, you would run:

     

    phoronix-test-suite install blake2

     

    This will install the blake2 test and try to address any unmet dependencies (e.g. install packages which that benchmark requires to run that aren’t already installed). To run an installed test, issue the following command (using blake2 as an example again):

     

    phoronix-test-suite benchmark blake2

     

    If you are interested in running a suite of tests (or just want to run a few tests without having to individually install the lot of them) you can list whole suites of tests at once with:

     

    phoronix-test-suite list-available-suites

     

    The install process is the same as for an individual test:

     

    phoronix-test-suite install [suitename]

     

    If you’re looking to measure a specific metric there’s plenty to choose from here – there’s a lengthy list of available tests and suites. As an example of results, here’s the chess benchmark:

     

    ubuntuBenchmark-phoronix-chess

  • Ubuntu Server Benchmarks: Hardinfo

     

    Hardinfo is one of the command-line benchmarks available for Ubuntu Server – it does have graphical features so it will also be useful for Ubuntu Desktop users, but for the purpose of this piece we will assume you’re at a terminal. It not only runs benchmarks like Blowfish but also shows you a great deal of information about the system itself, like ARP tables, sensors, CPU/RAM details and more.

     

    To install, run the following:

     

    sudo apt-get install hardinfo

     

    You can run it without using less to view the results, but you’ll probably want to pipe the results to less to make it a bit easier to navigate the pages of text. Run it with the following:

     

    hardinfo | less

     

    This pipes the output to the “less” command – once the command completes you will be able to navigate the results with the up/down and pageup/pagedown keys. To quit less press “q”. At the bottom of the results are the benchmarks; they will look something akin to this:

     

    ubuntuBenchmark-hardinfo

     

    The benchmark in this case was run on an ESXi VM with two 2.3GHz CPUs. It’s not the prettiest output but it provides quite a bit of potentially useful information. The output from hardinfo is a whole lot prettier when you have a GUI!

  • How to set up SNMP monitoring (snmpd) on Ubuntu 12.04

     

    This one caused a bit of hassle recently – a few online guides don’t seem to work with the current version of Ubuntu. We found that this works, at least in the ~10 or so servers we have tried so far:

     

    sudo apt-get install snmpd

     

    Back up your snmpd.conf file:

     

    sudo mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.old

     

    Create a new file:

     

    sudo touch /etc/snmp/snmpd.conf

     

    Edit with your chosen editor and put in the following:

     

    rocommunity public

    syslocation “Describe the server’s location”

    syscontact [email protected]

     

    Save and exit. Now edit the following file:

     

    /etc/default/snmpd

     

    Comment out the following line by putting a # before it:

     

    SNMPDOPTS=’-Lsd -Lf /dev/null -u snmp -g snmp -I -smux -p /var/run/snmpd.pid’

     

    On the next blank line add the following:

     

    SNMPDOPTS=’-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid -c /etc/snmp/snmpd.conf’

     

    Save the file and restart the SNMP daemon:

     

    sudo /etc/init.d/snmpd restart

     

    Now you should be able to successfully snmpwalk locally and from machines on the local network.

  • Ubuntu: How to update PHP’s timezone

     

    We came across this one recently when setting up a Zabbix server, where the installation would not proceed until the PHP timezone was set. This is quite straightforward – using your favourite editor edit:

     

    /etc/php5/apache2/php.ini

     

    Look for the Module Settings section or search for:

     

     date.timezone

     

    (in vi /date.timezone should get you there). Uncomment the line by removing the leading ; and then add in your desired timezone. For Sydney it would look like:

     

    [Date]

    ; Defines the default timezone used by the date functions

    ; http://php.net/date.timezone

    date.timezone = UTC+10

     

    Change UTC+10 to your desired timezone, save the file and restart Apache:

     

    sudo service apache2 restart

     

    Voila!

  • How to remove/delete old or unused kernels in Ubuntu

     

    If you have upgraded your kernel you will have found that Ubuntu keeps the older ones around, which can be handy if something breaks in the newer kernel and you have to boot from your old system. Over time, however, these can add up in terms of the amount of space consumed – at around 150MB per kernel you could easily find yourself with over a GB of old kernels if you’ve upgraded enough times. In this example the system we are using is Ubuntu 12.0.4.2. If you’re using Ubuntu Desktop, open up a terminal window – if you’re using Ubuntu Server, log in as usual and run:

     

    uname -r

    to see which kernel you are currently running. Make sure not to delete this one. Now, to see a list of the installed kernels, we run:

     

    dpkg –list | grep linux-image

    This command lists the installed packages and filters the list to include only those which have “linux-image” in them, which should only be your kernels. Your list should look something along the lines of:

     

    ii  linux-image-2.6.32-33-server 2.6.32-33.72     Linux kernel image for version 2.6.32 on x86_64
    ii  linux-image-3.2.0-35-generic 3.2.0-35.55      Linux kernel image for version 3.2.0 on 64 bit x86 SMP
    ii  linux-image-3.2.0-38-generic 3.2.0-38.61      Linux kernel image for version 3.2.0 on 64 bit x86 SMP
    ii  linux-image-server           3.2.0.38.46      Linux kernel image on Server Equipment.

     

    To remove a kernel, run the following:

     

    sudo apt-get purge [kernel]

     

    Using the above list, say we want to get rid of 3.2.0-35. In that case the command would be:

     

    sudo apt-get purge linux-image-3.2.0-35-generic

     

    Once you have removed your unwanted kernels run:

     

    sudo update-grub2

     

    This will update the boot menu accordingly.

  • Monitoring network usage on Ubuntu

     

    If you want to see how much traffic is passing through your network port there’s a handy tool called vnstat which will tally the amount of data passing through. You can install it with:

     

    sudo apt-get install vnstat

     

    It will usually add the databases and network ports automatically like so:

     

    vnstat-0

     

    If it doesn’t and gives you an error you can create the database(s) with:

     

    sudo vnstat -u -i eth0

     

    If you have multiple network cards/ports you can add those in, too:

     

    vnstat -u -i eth1

    vnstat -u -i eth2

    …etc

     

    If it couldn’t create the databases you can start it with:

     

    sudo /etc/init.d/vnstat start

     

    If you need to change the maximum bandwidth from 100Mb you can edit the file:

     

    /etc/vnstat.conf

     

    Scroll down until you see the following:

     

    # maximum bandwidth (Mbit) for all interfaces, 0 = disable feature
    # (unless interface specific limit is given)
    MaxBandwidth 100

     

    and make MaxBandwidth the figure you require (e.g. 1000). If you make a change restart vnstat with:

     

    /etc/init.d/vnstat restart

     

    You can now see how much traffic has come through the NIC since vnstat started recording – at first it probably won’t be much (if any), but as it adds up you can check it with:

     

    vnstat

     

    The output should look like:

     

    vnstat-01

     

    You can watch how much traffic is flowing through in real-time by running:

     

    vnstat -i eth0 -l

     

    This will give you a screen showing you the current traffic:

     

    vnstat-02

     

    You can end this with CTRL+C, which shows you a summary screen:

     

    vnstat-03

     

    You can get an hourly summary with:

     

    vnstat -i eth0 -h

     

    vnstat-04 vnstat-05

     

    Daily summary with:

     

    vnstat -i eth0 -d

     

    vnstat-04

    Monthly summary with:

     

    vnstat -i eth0 -m

     

    vnstat-06

     

    This is a really handy way of keeping track of your network traffic – whether it’s out of curiosity, wanting to know how much stress your network is under or looking for a bottleneck this can be quite a valuable tool.

  • How to find number of cores in Ubuntu (or other versions of Linux)?

     

    If you’re using a virtual server (whether online or your own physical machine) it can be handy sometimes to check how many CPU cores are available; here are two easy methods of doing this. The first:

     

    nproc

     

    This will return a single number, whether it be 1, 2, 4 or otherwise. For a more detailed look, try:

     

    lscpu

     

    This will usually give a more complex readout, e.g.:

     

    root@server [/]# lscpu
    Architecture:          x86_64
    CPU op-mode(s):        32-bit, 64-bit
    Byte Order:            Little Endian
    CPU(s):                1
    On-line CPU(s) list:   0
    Thread(s) per core:    1
    Core(s) per socket:    1
    CPU socket(s):         1
    NUMA node(s):          1
    Vendor ID:             GenuineIntel
    CPU family:            6
    Model:                 45
    Stepping:              7
    CPU MHz:               2000.024
    BogoMIPS:              4000.04
    Hypervisor vendor:     Xen
    Virtualization type:   para
    L1d cache:             32K
    L1i cache:             32K
    L2 cache:              256K
    L3 cache:              15360K
    NUMA node0 CPU(s):     0

     

  • How to kill a process after a set period of time

     

    Knowing how to limit how long a process will run for is quite useful, particularly when you have daily backup scripts and the like which may at times run more than 24 hours; having multiple processes attempting to synchronize the same files can waste time, bandwidth and CPU power needlessly. The command we will use here is timeout. Ubuntu Server should have this pre-installed. It is used so:

     

    timeout [no. of seconds] [command]

     

    e.g.

     

    timeout 10 rsync /home/user/files/ /backups/user/files/

     

    would run the above rsync command but kill it after 10 seconds.

     

    This can be particularly useful with your daily scripts; simply set the timeout to be a few minutes less than 24 hours and you should hopefully avoid them running over each other. For reference there are 3600 seconds in an hour and 86400 seconds in 24 hours; setting a process to timeout after 86000 seconds would result in it running for 23 hours, 56 minutes and 20 seconds.