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    Use gs or ghostscript as below, specify the output file and also the input file. In the example below the output file is "outputfile-resized.pdf" and the input file is "original-pdf.pdf". Change the input file to the name of your pdf gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/prepress -dNOPAUSE -dQUIET -dBATCH -sOutputFile=outputfile-resized.pdf original-pdf.pdf For........
  • Ubuntu Linux Mint Debian Redhat Youtube Cannot Play HD or 4K videos, dropped frames or high CPU usage with Nvidia or AMD Driver


    In a lot of distros, vdpau which accelerates video through the GPUis often not installed even in recent distros. This will result in Firefox with Youtube dropping frames when you check the "Stats for Nerds" and to the eye as jerky or slower video playback due to the dropped frames. Some sites will say that because you are watching VP09 that there is no GPU support, but with vdpau installed and enabled, many GPUs will still be able to use hardware decoding for 4K........
  • Linux dhcp dhclient Mint Redhat Ubuntu Debian How To Use Local Domain DNS Server Instead of ISPs


    If you are running a local DNS server like named/bind and don't want to use the ISPsupplied DNS servers that are announced via a DHCP request (using dhclient) then the solution is simple. The reason should be obvious, but normally running your own DNS server will provide a more reliable, and fast DNS response and you won't have to worry about filtering as much (unless your upstream filters or proxies outgoing DNS requests). Edit /etc/dhcp/dhclient.conf........
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    If you get this error, it is often because you have configured Apache with modules that weren't actually installed. Eg. you try to load the PHPmodule but didn't actually install the apache2 php module, so the server can't start. In general, this error can often be caused by issues with problematic modules and/or Apache being configured for modules that have not actually be installed (eg. libapache2-mod-php) is missing. The above results in this less than obv........
  • How to use the FTDI USB serial cable to RJ45 adapter to connect to the console on Cisco/Juniper Switch Router Firewall in Linux Ubuntu Debian Redhat


    This should work for most console ports of other manufacturers too. It is a quick and simple method for emegencies or deploying a few appliances/devices in a non-standard environment or small environment. However, if this is a route thing, or the equipment is not physically close to you, it would be best to use some sort of "Terminal" server which is an IP connected switch with several serial ports built-in for this purpose. Normally they accessible by web/........
  • Linux How To Access Original Contents of Directory Mounted Debian Mint CentOS Redhat Solution


    Let's say you have a directory /mnt/raid which has files and directories inside it, but nothing is mounted to it. Then you mount a block device such as /dev/sdh to /mnt/raid Even though /mnt/raid has files and directories there, you can only see the mounted contents of /mnt/raid. How do we access the original contents? Just do a bind mount of the root filesystem to another location. mkdir /bindmount mount --bind / /b........
  • Linux How To echo as root solution to use tee permission denied solution Ubuntu Debian Mint Redhat CentOS


    The issue is when you need to echo something as root/sudo, that it doesn't work. You can never do a sudo echo to an output file as you'd expect. Take an example to clear out wasted RAM buffers/cache like this: sudo echo 1 > /proc/sys/vm/drop_caches -bash: /proc/sys/vm/drop_caches: Permission denied The solution is to run tee as sudo/root What we do is echo 1, but then pipe it to the "tee" command as sudo........
  • How To Add Multiple SSH Keys Ubuntu Mint Linux Debian Redhat


    By default if you create a private key for SSH, it will create something like .ssh/id_rsa Linux will always search for and offer this key when connecting to servers. If you put extra keys in your .ssh directory like id_rsa_realtechtalk.com, they will be ignored by default and NOT used or offered (you can verify this with ssh -v) and see it is not being offered. Here is how you add the extra SSH keys so they are all offered: #this gives........
  • Ubuntu Linux Mint Debian Redhat Cannot View Files on Android iPhone USB File Transfer Not Working Solution


    If you plugin your phone to your computer and enable USB File Transfer/Allow on the phone side but the contents of your phone on the computer side are empty in the file manager, you probably don't have mtp-tools.MTP or media transfer protocol is the standard protocol that most phones use to communicate over USB to the computer. Just do this to fix it and get access to your files: apt install mtp-tools After that you should be a........
  • Enable Turbo Mode for CPU Ubuntu Linux Mint Debian Redhat


    Sometimes due to your BIOS/EFI you may find that you have chosen "Energy Efficient" for your CPU which may effectively disable turbo mode. This is because "Energy Efficient" will often restrict or throttle your CPU to the base speed. This can impact nearly any CPU such as Intel's, AMDs, Opteron, Xeon etc... This is of course frustrating, for example if you have a CPU that is 2.0GHz base speed but turbo to 2.5GHz, you will never hit more than 2GHz.........
  • CentOS 7 / 8 cannot boot with with mdadm RAID array solution


    This article about migrating to a CentOS 7 /8 RAID mdadm array has a lot of info but I wanted to focus specifically on what newer versions of CentOS 7 require to boot mdadm and what changes are necessary on CentOS 7.8+ CentOS 7 / 8 mdadm RAID booting requirements This assumes you are chrooting into an existing install or using it to get a new deployment ready. However, these steps can........
  • br0: received packet on bond0 with own address as source address Linux Solution Mint Debian Redhat CentOS bridge bridging


    A quick fix is to run this command: sudo brctl setageing br0 0 This causes the aging of the MAC address to time out immediately or in 0 seconds, which delete the entry frmo the FDB (Forwarding Database) and causes the error to go away. The default time is 300 seconds or 5 minutes. You can also add it under your br0 definition like this in /etc/network/interfaces to make it permanent and automatic: auto br........
  • bash how to hide username/customize prompt Linux Debian Redhat Ubuntu Solution


    Just edit your ~/.bashrc and add this at the very end: export PS1="realtechtalk.com" Then your prompt will look like this: bladeblox:uptime 08:47:14 up 48 min, 1 user, load average: 1.00, 1.07, 0.96 If you wanted a dollar sign at the end then you would change it like this: export PS1=&........
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    It really seems limited in that it can mainly give you the things you would see on the physical unit such as load etc.. wget https://downloads.sourceforge.net/project/apcupsd/apcupsd%20-%20Stable/3.14.14/apcupsd-3.14.14.tar.gz?r=https%3A%2F%2Fsourceforge.net%2Fprojects%2Fapcupsd%2Ffiles%2Flatest%2Fdownload&ts=1598115866 tar -zxvf apcupsd-3.14.14.tar.gz cd apcupsd-3.14.14 [root@somebox apcupsd-3.14.14]# ./conf........
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    function centos7 { release=`cat /etc/redhat-release|awk '{print $4}'|grep ^[7]` if [ "$release" != "" ]; then centos7='yes' fi } centos7 echo "$centos7" We create a function called "centos7" and then call it by just typing "centos7" We then access a variable that may be set........
  • Migrate Centos 7 from Single HDD to mdadm RAID 10 array:


    Done on Centos 7.3 very important as clearly based on older guides it was a lot easier and more simpler! Hint do not use grub2-install! If you have trouble booting after this check this CentOS mdadm RAID booting/fixing guide. One huge caveat if you are an oldschool user or sysadmin who has avoided UEFIbooting The nor........
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    service named status rndc: connect failed: 127.0.0.1#953: connection refused named (pid 10557) is running... This issue is normally caused by a permissions issue where named doesn't have the permissions to read the rndc.key. Check /var/log/messages: Jan 4 17:06:22 storagebox named[10753]: none:0: open: /etc/rndc.key: permission denied Jan 4 17:06:22 storagebox named[10........
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    # yum -y install qemu-kvm Loaded plugins: fastestmirror Setting up Install Process Loading mirror speeds from cached hostfile * base: mirror.lzu.edu.cn * elrepo: ftp.utexas.edu * epel: ftp.jaist.ac.jp * extras: mirrors.aliyun.com * openvz-kernel-rhel6: mirror.fdcservers.net * openvz-utils: mirror.fdcservers.net * updates: mirrors.nwsuaf.edu.cn Resolving Dependencies........
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    cc: Internal error: Killed (program cc1) Please submit a full bug report. See for instructions. make: *** [ext/fileinfo/libmagic/apprentice.lo] Error 1 make: *** Waiting for unfinished jobs.... Stopping crond: ........
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    This is a handy link and list of all the relevant Directadmin log files and related servers. http://help.directadmin.com/item.php?id=11 DirectAdmin: /var/log/directadmin/error.log /var/log/directadmin/errortaskq.log /var/log/directadmin/system.log /var/log/directadmin/security.log Apache:........
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    I had a system running a 128MB live CD image with 2.8 gigs of available RAM and the OOM kernel killer went crazy when using dd for more than 8 minutes and kept killing everything. I've read that this is due to a low-memory issue and paging in the kernel and 32-bit systems with lots of RAM. I even enabled swapspace on my LiveCD and the issue happened 25 minutes into dd rather than 8 minutes, so what gives? Also no swap space was ever used! cat /proc/s........
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    I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts. This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem: We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........
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    http://apt.sw.be/redhat/el5/en/i386/test/repodata/repomd.xml: [Errno 14] HTTP Error 404: Not Found Trying other mirror. Error: Cannot retrieve repository metadata (repomd.xml) for repository: rpmforge-testing. Please verify its path and try again Notice it is complaining about "rpmforge-testing", just disable it for now: Solution is to edit the repo: vi /etc/yum.repos.d/rpmforge-testing.repo........
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    This function and others may not work with the stock PHPinstall on Centos/CPanel: Fatal error: Call to > undefined function imagecreatefromjpeg() Even with libjpeg-devel installed it won't work because PHP was not compiled with jpeg support, so we have to do the dirty work ourselves :) Here is the command/yum's I did to install missing libraries for PHP that configure will complain about (yes it is a one by one process). yum install bzip2-........
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