/ - rtt - IT Resource

  • 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........
  • 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........
  • Ubuntu/Debian OpenVZ Template Problems No Networking and SSH not starting


    It all comes down to a bug essentially where you are running an older kernel that doesn't support the newer Debian templates.  The solution is to update your OpenVZ kernel. Here are some symptoms of the problem/lack of kernel support:   Ubuntu Template 12.04 requires a manual network start: service networking start sshd will not start: /usr/sbin/sshd PRNG is not seeded mknod /dev/random c 1 8........
  • Weird Ubuntu Issues with NVIDIA driver/Compiz


    1.) My screensaver would take a long time to disable after hitting a key. 2.) Usually errors like below will follow. 3.) Compiz sometimes uses 100% or high CPU 4.) My window controls will disable (eg. the minimize, maximize and close buttons). It seems like Compiz or appearance/effects disable themselves.  Re-enabling Desktop Effects under Appearance temporarily fixes it. 5.) high load in general from things like "Migration" pr........
  • 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.........
  • mysql how to kill individual process/query


    Enter the console as root mysql -u root -p Then kill the process (where 1234 = the thread ID) kill 1234 It's also a good idea to use a tool like "mtop" to monitor which processes and queries are slow, killing them is a temporary fix while you try to isolate the actual problem.........
  • /usr/local/cpanel/bin/apache_conf_distiller 100% cpu


    On some CPanel installs we see complaints of "/usr/local/cpanel/bin/apache_conf_distiller" causing 100% cpu usage without any solution. Killing the process causes it to spawn again, actually it seems it tends to spawn multiple processes itself. Restarting CPanel itself is a temporary but not permanent solution.........
  • Linux find what processes are swapping


    Here is a handy script that will check all processes and report what is swapping #!/bin/bash for pid in `ps x|awk '{print $1}'`; do result=`cat /proc/$pid/status|grep VmSwap|awk '{print $2}'|grep -v ^"0"` if [ ! -z "$result" ]; then  programresult=`ps x|grep $pid|grep -v grep`  if [ $? == 0 ]; then      program=`echo $programresult|awk '{print $5}'|grep -v ^grep`........
  • Kernel panic - not syncing: Attempted to kill init! Pid: 1,comm: init Tained: G I------------- 2.6.32-358.el6.x86_64 #1 Call Trace: [] ? panic+0xa0/0x16f [] ? do_exit+0x862/0x870 [] ? fput+0x25/0


    Kernel panic - not syncing: Attempted to kill init! Pid: 1,comm: init Tained: G        I-------------    2.6.32-358.el6.x86_64 #1 Call Trace:  [<fffffff8150cfc8>] ? panic+0xa0/0x16f  [<fffffff81073ae2>] ? do_exit+0x862/0x870  [<fffffff81182885>] ? fput+0x25/0x30  [<fffffff81073b48>] ? do_group_exit+0x58/0xd0  [<fffffff81073bd7>] ? sys_exit_........
  • Nearly 100% CPU Usage from processes called dma0chan0 dma0chan1 dma0chan2 dma0chan3


    I never started these processes but they are from a custom based bootable Linux I've made and I've never seen this behavior on other machines or even with the same machine using different kernels.  These processes seemed to spawn on their own and I have no idea why and even worse why the CPU usage is so high? Here's the output from top:   907 extaudit  30  10     0    0    0 R 90.7  0.0 ........
  • How to view UDP and other protocol connections?


    netstat is weak and can't show udp connections and most other protocols, use "ss" which is what netstat should have been: The "-u" switch stands for udp, here's a list of other options: Usage: ss [ OPTIONS ]        ss [ OPTIONS ] [ FILTER ]    -h, --help        this message    -V, --version    output ver........
  • Apache Crash Solution Can't Restart Due to Socket In use - (98)Address already in use: make_sock: could not bind to address [::]:80 (98)Address already in use: make_sock: could not bind to address 0.0.0.0:80 no listening sockets available, shutting d


    (98)Address already in use: make_sock: could not bind to address [::]:80 (98)Address already in use: make_sock: could not bind to address 0.0.0.0:80 no listening sockets available, shutting down This will even trip you up if you have a service like monit to save you if httpd crashes.  The only way to fix this is to either wait (it's not an option for production situations) or to kill the ghost httpd processes that wouldn't gracefully close: So........
  • Apache MPM worker vs prefork


    find what MPM Apache is using, it will either be using "worker" or "prefork" apachectl -l Compiled in modules:   core.c   prefork.c   http_core.c   mod_so.c In my case it is "prefork" vi /etc/httpd/conf/httpd.conf Find the section that looks like this (by default one will normally exist for prefork and for worker, but in my case I only care a........
  • sshfs cannot unmount error: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1))


    umount: /home/diret/mount: device is busy.         (In some cases useful info about processes that use          the device is found by lsof(8) or fuser(1)) I tried everything (fusermount -u) to unmount it but the only thing that worked was actually doing this: ps aux|grep sshfs Then I identified the sshfs connection and did: kill -kill pid........
  • exim high load and dozens of processes


    This server was experiencing loads of up to 80 and maxing out the RAM and kmemsize on a CPanel VPS.  There were literally dozens if not hundreds of exim processes.  I have no idea why exim has such a design that would allow it to consume this much CPU and RAM.  Any normal MTA should not be spawning so many processes, it should be processing them in sequence and if it is going to spawn hundreds of processes in response to a large volume of mail, it's better to have a delayed del........
  • OpenVZ user_beancounters kmemsize failcnt Processes Timing Out/Doing Nothing/Zombie


    cat /proc/user_beancounters produces the following: kmemsize        1861537    5139870   12752512   12752512   26965041 Notice the failcnt "26965041", that is for kmemsize and at first it confused me.  The system had enough guaranteed and enough burst RAM available.  kmemsize is a variable indepedent of that, but who cars about the explanation right, let's just make thing........
  • How to Track Down/Find Cause of Linux high disk iowait/wa


    top - 09:34:12 up 2 days, 20:57,  2 users,  load average: 1.83, 1.99, 2.03 Tasks:  59 total,   2 running,  57 sleeping,   0 stopped,   0 zombie Cpu(s):  0.3%us,  0.0%sy,  0.0%ni,  0.0%id, 99.7%wa,  0.0%hi,  0.0%si,  0.0%st That 99.7% wa is iowait, it means the server is waiting for a process to complete an IO operation or in plain English, there is a delay in........
  • iPhone Backgrounder Adds True and Real iPhone multitasking on jailbroken phones


    Apple crippled the iPhone by not allowing multi-tasking of the non-primary apps.  I use SSH a lot and I don't want to close my session just to check my e-mail, etc, now an app found in Cydia called "Backgrounder" allows just that. Although it's not perfect, we installed the correct one for "3.x" iPhones and hit "Reload SpringBoard" and the hour/circle glass has just been going for minutes. It seems like it installed fine even with the crash t........
  • Latest Articles

  • syntax error, unexpected T_SL in PHP Solution
  • grep regular expression match number range between specific numbers
  • bash how to print out lines of text within a range from the first occurrence
  • bash script how to to check LAN computers for open ports
  • MySQL Using mytop Debug Source of High IO and Slow Performance
  • How To Mathematically Convert and Calculate Binary Value To Decimal Value
  • systemd management using systemctl and journalctl to check systemd logs
  • css how to format code in the code tag
  • css br with extra blank line
  • What is /dev/pts and why do we need it in Linux?
  • Linux What is umask (user mask) for file and directory creation permissions and how to calculate umask and change the defaults
  • Linux Permissions and Groups Real Usecase for Group Access
  • Centos 7 python34 how to install the gi library
  • Centos 7 - Convert Minimal to Graphical GUI GNOME or KDE Desktop
  • AMD Set Fan Speed and Other Powerplay Memory/CPU Timings with a Linux script
  • Ethereum Mining Claymore Nanopool Error
  • genisoimage errors with long filenames and deep directory structures
  • Linux Kernel USB Export Errors
  • How to download gajim 0.16.9 XMPP/Jabber client so you can use OMEMO encryption
  • HP DL385 G7 Linux BIOS Update Flash