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  • systemd management using systemctl and journalctl to check systemd logs


    systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system. The key commands or arguments you will use with systemctl are the following: Unit Commands:   list-units [PATTERN...]         List loaded units &nbs........
  • Linux bash shell doesn't show username, hostname or current path fix solution


    Usually this is because when you created your user you added a user but didn't create their home directory and/or for some reason your .bashrc and .bash_profile in ~ (home) is broken/missing. In your home just create the following files with the following content to solve it: .bashrc and .bash_profile. To apply it just relogin/start a new bash session # .bash_profile # Get the aliases and funct........
  • PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/geoip.so' - /usr/lib64/php/modules/geoip.so: undefined symbol: GeoIP_country_code_by_name_v6 in Unknown on line 0


    PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/geoip.so' - /usr/lib64/php/modules/geoip.so: undefined symbol: GeoIP_country_code_by_name_v6 in Unknown on line 0 Solution: Edit geoip.ini vi /etc/php.d/geoip.ini Comment out the .so like so: ;extension=geoip.so service httpd restart........
  • postfix errors fatal: no SASL authentication mechanisms /usr/libexec/postfix/smtpd: bad command startup -- throttling solution


    Jul  3 22:12:17mailserver postfix/smtpd[6195]: fatal: no SASL authentication mechanisms Jul  3 22:12:18mailserver postfix/master[4881]: warning: process /usr/libexec/postfix/smtpd pid 6195 exit status 1 Jul  3 22:12:18mailserver postfix/master[4881]: warning: /usr/libexec/postfix/smtpd: bad command startup -- throttling This only ever happens in my experience when the authentication method is actually Dovecot.  Usually the problem........
  • Intel NUC J3455 Linux Kernel freeze slowness 4.4.98 errors


    It looks like this has something to do with APIC but I am not sure.  I have similar CPUs with a different MB and BIOS that work fine on the same type of kernel.  A lot of time the issue is because of the C-step setting in the BIOS. The same thing happened on the 2.6 kernel with Centos 6 but this is a homebrew 4.4 kernel so I am not sure why it is happening when even Centos 7 (3.2) kernel works OK. Solution - It comes down to the BIOS set........
  • Unable to load dynamic library '/usr/lib64/php/modules/module.so' - /usr/lib64/php/modules/module.so: cannot open shared object file: No such file or directory in Unknown on line 0


    Getting this error on Centos 6 with PHP 5.3 when just running "php -v"   PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/module.so' - /usr/lib64/php/modules/module.so: cannot open shared object file: No such file or directory in Unknown on line 0 PHP Warning:  Cannot load module 'XCache' because conflicting module 'apc' is already loaded in Unknown on line 0 Solution:........
  • How to start screen in bash script or from /etc/rc.local on startup as a specific user


    It takes some tinkering the main thing is that the "-dmS" flag allows screen to start without a session which of course sudo won't have. solution: /usr/bin/sudo -u user /usr/bin/screen -dmS nameyouchoose /script/start.bash this doesn't work at all: /usr/bin/sudo -u user "/usr/bin/screen /script/s........
  • PHP geoip.so fatal error Solution


    PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/geoip.so' - /usr/lib64/php/modules/geoip.so: undefined symbol: GeoIP_country_code_by_name_v6 in Unknown on line 0  Remove the GEOIP from PHP: php71w-pecl-geoip-1.1.1-1.w6.x86_64   PHP Fatal error:  PHP Startup: apc_shm_create: shmget(0, 67108864, 914) failed: Invalid argument. It is possible that the........
  • Centos 6.6/6.9 KVM VM Kernel Panic On Boot - Kernel panic - not syncing: Attempted to kill init!


    I am not sure why this is happening neither the hostnode or VM changed.  All I did was reboot the hostnode and startup the Centos VM again, also note it happened with the original kernel on the VM and also the latest 6.9 kernel as of this writing as shown below. Host Node: Centos 6.9 Kernel: 2.6.32-696.6.3.el6.x86_64  Kernel: 2.6.32-042stab123.9 Same result in any kernel above........
  • ERROR 2013 (HY000): Lost connection to MySQL server during query


    The solution is simple but strange, if you copy your /var/lib/mysql directory to another server and think it will work, be sure to check if you have /var/log/mysql and binary log files.  If you do, the server will not work and will give you errors like below and crash without the proper log files. UPDATE user SET password=password("newpass") WHERE user='root'; flush privileges; ERROR 2013 (HY000): Lost connection to MySQL server durin........
  • apc_shm_attach: shmat failed: in Unknown on line 0 & apc_shm_create: shmget(0, 67108864, 914) failed PHP Solution


    PHP Fatal error:  PHP Startup: apc_shm_create: shmget(0, 67108864, 914) failed: Invalid argument. It is possible that the chosen SHM segment size is higher than the operation system allows. Linux has usually a default limit of 32MB per segment. in Unknown on line 0 PHP Fatal error:  PHP Startup: apc_shm_attach: shmat failed: in Unknown on line 0 This error is not at all fun because it actually prevents Apache/httpd from starting or working at all. It will........
  • Virtualbox errors on Ubuntu/Debian/Mint


      The solution was to reinstall the vbox dkms package and do a manual modprobe of the modules it makes. I never sorted out the unable to start due to the USB issue, I did have the guest additions installed but the only way to boot was to change the pointing device from USB to PS2 and then to disable the USB controller (if your pointing device is set as USB, disabling USB will not work because it will re-enable by default when it sees your pointing device is USB, this is w........
  • kvm how to add secondary cdrom drive


    This is useful if you are installing Windows and need virtio but of course Windows needs the virtio driver which is on a second iso. This is the line of code you would add to your kvm startup script and then you get this iso as  second cdrom you can browse to for your Windows install of virtio driver's or whatever other use you need it for. -drive file=/kvmtemplates/virtio-win-0.1-94.iso,media=cdrom........
  • NS_ERROR_FAILURE (0x80004005) The virtual machine 'XP' has terminated unexpectedly during startup with exit code 1.


    The solution is to run '/etc/init.d/vboxdrv setup' and sometimes happens when upgrading VBox and the kernel modules don't get upgraded with it.  Sometimes the above doesn't work until you reboot because sometimes other unknown processes (even the file manager possibly)  may be locking the old module from being unloaded. Failed to open a session for the virtual machine XP. The virtual machine 'XP' has terminated unexpectedly during startup with exit code 1.........
  • 2CO/2Checkout how to create recurring payment subscription button dynamically


    It was hard to find this as I find most online payment processors don't just put the basic information in plain view. Remember to set your sid (your seller id).  The below can easily be turned into a scripted PHP template to integrate into your own custom or existing payment solution. http://help.2checkout.com/articles/How_to/How-to-Sell-Recurring-Products-with-2Checkout/........
  • Centos how to upgrade from PHP 5.2 to 5.3 without downtime


    This may sound silly but there will be conflicts/issues with the default Centos repository so you have to use a third party like remi (I prefer not to do this but it's the only option unless you migrate your sites/data to another server or can stand some downtime-not an option IMHO on a production server). You may need to upgrade to PHP 5.3 to run Joomla or many other reasons. Your host needs to use PHP 5.2.4 or higher to run this version of Jo........
  • Enable SPAMASSASSIN on Postfix in 5 minutes


    Centos 5 Postfix and SPAMASSASSIN Tutorial yum install spamassassin chkconfig spamassassin on vi /etc/mail/spamassassin/local.cf ############## #required_hits 5 #report_safe 0 #rewrite_header Subject [SPAM] #5 is the least restrictive (means only the most obvious SPAM is caught. 0 is obviously the most restrictive/sensitive and would have lots of false positives require........
  • ls: error while loading shared libraries: libtermcap.so.2: cannot open shared object file: No such file or directory solution


    ls ls: error while loading shared libraries: libtermcap.so.2: cannot open shared object file: No such file or directory This is not an ldd problem or case of anything missing, this only happened after I upraded Ubuntu. declare -x PATH="/home/user/bin:/usr/local/bin:/usr/bin:/bin:/usr/games" "/home/user/bin" is the problem!  It's weird because I have no idea how it happened.........
  • Ubuntu 10.04/GNOME Volume Control Missing From Panel/Indicator Applet


    What this really refers to is gnome-volume-control-applet which is what controls the volume in the panel/indicator applet. In Ubuntu 10.04 it is just the applet mentioned above, run that from the command line and it will start. I lost mine when I removed pulseaudio trying to fix audio issues with Flash and Opera.  It also removes the gnome-volume-control-applet from starting.  *I also note........
  • Ubuntu/Debian DRBD 8.0 Setup Guide


    I've only used it on Centos, so I thought I'd make a quick Debian guide: Install the DRBD Package apt-get install drbd8-utils Reading package lists... Done Building dependency tree       Reading state information... Done The following packages were automatically installed and are no longer required:   libswfdec-0.8-0 Use 'apt-get autoremove' to remove them. The following........
  • Ubuntu 10.04 Linux is still not ready for the Desktop world


    I am a huge fan of Linux and the idea of OpenSource but I've said it many times, there are still hurdles in today in 2010 for Linux as a Desktop.  Linux is still intended for servers at its very core.  This can be changed succesfully though, as Apple has shown us with Mac OS X based on FreeBSD. Half of the issue is lack of driver support and the other half is the Linux Kernel and Window Manages, KDE and GNome still both don't cut it (but they're getting closer). I'll........
  • XBOX 360 No Sound over HDMI Solution/Fix


    My XBOX's dashboard/firmware was from sometime in 2008 when I first bought the system.  I mainly played using composite cables but at my brother in law's house we used HDMI.  The very first time it worked, but then I bought some games that did some update and after that HDMI never worked. The symptoms besides having on sound is that your XBOX will show PC monitor resolutions but won't have any option to say you have a 720P or 1080P display, this means the XBOX firmware is fa........
  • Use rcconf to edit startup/init.d/init scripts on Debian/Ubuntu based distributions


    I've never understood how to enable and disable services for different run levels in Debian based distros, it's just weird, annoying and doesn't make sense.  I much prefer chkconfig from RHEL. Just install the package called 'rcconf' and be done with it.  rcconf makes things easy for you. apt-get install rcconf Reading package lists... Done Building dependency tree        Reading state information... Done........
  • Enable/Disable PHP Warnings/Logs and Errors from .htaccess with Apache


    Put what you see below into your .htaccessand it will enable errors and notices. (change on to off and 1 to 0 to disable though) php_flag display_startup_errors on php_flag display_errors on php_flag html_errors on Now you'll be able to see errors and notices but this should really only be used for debugging purposes and only temporarily as it can be a security issue since errors can reveal information you wouldn't want hacker........
  • yum error not working rpmdb: mmap: No such device TypeError: rpmdb open failed


    Loaded plugins: fastestmirror rpmdb: mmap: No such device error: db4 error(19) from dbenv->open: No such device error: cannot open Packages index using db3 - No such device (19) error: cannot open Packages database in /var/lib/rpm Traceback (most recent call last):   File "/usr/bin/yum", line 29, in ?     yummain.user_main(sys.argv[1:], exit_code=True)   File "/usr/share/yum-cli/yummain.py&qu........
  • How To Save iptables firewall rules Centos/Redhat/Fedora Linux


    This is something that annoys a lot of people, fortunately the Redhat style OS's are the most simple in this respect.  I disagree that Debian's way makes sense, it is more of a hackish approach in how they implement iptables. Anyway, for those who are using Redhat/Centos style OS's it is very simple. Set your rules from the shell/command prompt and to save the iptables firewall rules so they are remember/loaded on boot just run this command: service iptables........
  • Configuring OCFS2 Clustered File System on Debian Based Linux including Ubuntu and Kubuntu


    There's a lot of information and guides on OCFS2 for RHEL and Centos Linux but the package setup and configuration is slightly different and this has thrown some people off. Installing OC2FS You should install the following packages to get started: apt-get install ocfs2-tools ocfs2console Configure OC2FS In RHEL/Centos the main configuration file is located in /etc/sysconfig/o2cb However in Debian based Linux it is located........
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