/ - rtt - IT Resource

  • bash script how to to check LAN computers for open ports


    In this case it just searches for port 80 it is fairly handy if you have some sort of appliance or something else you aren't sure of the IP of Of course change the port 80 port to whatever port(s) you want. for ip in `arp -n|arp -n|tail -n +2|head -n -1 |grep -v incomplete|awk '{print $1}'`; do  echo "checking $ip:80"  nc -w 1 -z $ip 80  if [ "$?" == 0 ]; then   echo "**Port 8........
  • AMD Set Fan Speed and Other Powerplay Memory/CPU Timings with a Linux script


    You can do other things but this particular script is just to set all AMD cards to 80% fan speed (remember this script needs to applied everytime you reboot). You could set it is a cron or just throw it into /etc/rc.local basepath=/sys/class/drm for hwmon in `ls -1 /sys/class/drm|grep card[0-99]$`; do echo card=$hwmon; hwmonname=`ls $basepath/$hwmon/device/hwmon|grep hwmon[0-99]` hwmonpath=$basepath/$hwmon/device/hwmon/$hwmonname echo "ec........
  • How to download gajim 0.16.9 XMPP/Jabber client so you can use OMEMO encryption


    #Linux Mint 18.2 how to install gajim .16.9 so you can use OMEMO encryption: sudo apt-get install python-axolotl python-nbxmpp wget https://gajim.org/downloads/0.16/gajim-0.16.9.tar.gz tar -zxvf gajim-0.16.9.tar.gz cd gajim-0.16.9 ./autogen.sh ;make;sudo make install #if you get this error you need to get a newer python-nbxmpp from here: gajim Gajim needs python-nbxmpp >= 0.6.1 to run. Quiting...........
  • How To Enable Nested KVM so guests can virtualize with hardware extensions


    #check if nested KVM is enabled by doing a cat on nested inside sys root@s14:~# cat /sys/module/kvm_intel/parameters/nested  root@s14:~# echo "options kvm-intel nested=Y" > /etc/modprobe.d/kvm-intel.conf root@s14:~# echo "options kvm-amd nested=1" > /etc/modprobe.d/kvm-amd.conf root@s14:~# modprobe -r kvm_intel modprobe: FATAL: Module kvm_intel is in use. root@s14:~# modprob........
  • VMWare ESXi 6.7 SSH/PowerShell CLI Commands


    [root@localhost:~] BootModuleConfig.sh          echo                         host-ind                     nfcd                   ........
  • Debian Mint Ubuntu compiling xmr-stak


    sudo apt-get install libcurl4-openssl-dev git build-essential autotools-dev autoconf libcurl3 sudo apt-get install libcurl4-gnutls-dev git clone https://github.com/wolf9466/cpuminer-multi sudo apt-get install cmake  libpthread-* libmicrohttpd-dev libssl-dev libhwloc-dev git clone https://github.com/fireice-uk/xmr-stak-cpu.git make install cd bin chmod +x xmr-stak-cpu ./xmr-stak -O xmr........
  • Centos 7 - How To Install NFS and Mount Remotely


    1.) First install nfs-utils [root@bcitcourse ~]# yum -y install nfs-utils Loaded plugins: fastestmirror base                                                         &n........
  • Linux How To Free Wasted Memory RAM in Buffers


    We all know Linux is known for good memory management but is it really?  It seems all on its own with hardly anything running that you can come back in days or weeks and find that almost all of your RAM is used! And many will say "no don't worry it's buffers for optimization" but it doesn't seem to help because what is in buffers is not available to use for new programs running or ones that allocate more RAM as far as I can tell. The reason I know........
  • mail command line examples of how to send an email using Linux / Unix and the Bash Shell or Scripting


    A simple way that may work for a lot of people who just need basic output for their scripts or daemons to announce an action is this: echo "body or message" | mail -s "realtechtalk.com" user@domain.com If you want to send a text file as the body just do this instead: mail -s "realtechtalk.com" user@domain.com < /tmp/sometxtfile.txt These a........
  • mdadm how to stop or start a check


    It's fairly simple to start or stop a check but I do wish mdadm's command had this built in.  Sometimes it will do a check at the worst time causing the server to crawl to a halt. Stop check on md126: echo idle > /sys/block/md126/md/sync_action Start check on md126: echo check > /sys/block/md126/md/sync_action  ........
  • bash find line and replace howto


    First find the line number: awk '/what you are searching for/{ print NR; exit }' input-file 86 Now use sed to replace it: sed -i  86s/.*/"your replacement text"/ $file   Here is a full sample script to automate it: file=some/f........
  • possible SYN flooding on ctid 42131, port 80. Sending cookies. - Solution


    The Linux Kernel interpretated a very high volume of real traffic as a DDOS attack so it basically ends up blocking your web server. possible SYN flooding on ctid 42131, port 80. Sending cookies. Simple fix edit sysctl values for max_syn_backlog sysctl -w net.ipv4.tcp_max_syn_backlog=5000 To make them permanent edit /etc/sysctl.conf echo "net.ipv4.tcp_........
  • Install Windows From a Linux TFTP Server instead of using WDS Solution


    yum -y install samba vi /etc/samba/smb.conf https://www.kernel.org/pub/linux/utils/boot/syslinux/syslinux-6.03.zip mkdir syslinux;cd syslinux;unzip syslinux-6.03.zip mkdir -p /tftpboot/libs/ cp bios/com32/modules/linux.c32 /tftpboot/libs/ cp bios/com32/libutil/libutil.c32 /tftpboot/libs/ cp bios/com32/lib/libcom32.c32 /tftpboot/libs/ #add lib path echo "PATH libs" >> /tftpboot/pxeli........
  • pcimodules and lspci not working alternative solution


    pcimodules no longer works it produces nothing probably because the format of /sys/bus/pci is different. lspci -k doesn't work on older lspci versions. pciutils can be compiled but it won't work if you have an old system and compile on a newer glibc. iteriate through /sys/bus/pci/devices/*/modalias cat /sys/bus/pci/devices/*/modalias pci:v00008086d00001237sv00000000sd00000000bc06sc00i00 pci:v00008086d00007000sv0000000........
  • linux how to answer yes to copy


    Have you have a command ask a question such as cp or move? You can do this: echo y|cp * /tmp/othercopy However it may still fail if your bashrc aliases have the "-i" flag see this post here.........
  • bash Linux how to get first or last letters of a word


    To get the first X letters of a word: It's very simple you can just pipe it to head with -c 1 (gives the first letter and so on) -c2 (2 gives the first 2 letters).   echo "dsjfsdlksjdklf;jlsd;kflasdj;kl"|head -c 2 Returns ds   To get the last X letters of a word: Now we use tail with -c but it works differently. ........
  • Linux bash script to see what connected computers respond to ping


    A great way when moving your equipment to a new location, new router/switch etc to help confirm what MAC has what IP:   for ip in `arp -na|awk '{print $2}'|sed s/(//g|sed s/)//g`; do echo ping $ip ping -c 1 -w 1 $ip > /dev/null if [ "$?" == 0 ]; then    echo "$ip UP" fi done........
  • Linux Mint USB Kernel Tainted and Locked Port/Dev File


    Essentially a program I was running for mining did not terminate properly with Ctrl+C it is listed as defunct and cannot be killed, kernel is tainted and normal tricks to disable the port are impossible the dev and sys entries for the device cannot be browsed or interacted with in any form without a lockup of the request.  The only solution is to reboot due to the kernel taint as far as I can find so far.   [1130246.811056] INFO: task minerd:21861 blocked for more th........
  • ffmpeg Linux Mint download, compile and install howto


    #if you have nvidia make sure you install the nvidia-cuda-toolkit so hardware acceleration can be used wget http://ffmpeg.org/releases/ffmpeg-3.3.2.tar.bz2 tar -jxvf ffmpeg-3.3.2.tar.bz2 cd  ffmpeg-3.3.2/ ./configure --disable-yasm install prefix            /usr/local source path              ........
  • Centos 7 How To Change Hostname


    Some guides still use the old Centos 6 style (do not use /etc/sysconfig/network). In Centos 7 the file is /etc/hostname echo "HOSTNAME=yourhostname.com" > /etc/hostname........
  • 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! One huge caveat if you are an oldschool user or sysadmin who has avoided UEFI booting The normal way will not work here if your Centos was using UEFI.  Newer systems use it by default. The easiest way to check is to do an fdisk -l if your sy........
  • USB 3.0 External HDD Enclosure Seagate UAS problems - [sdd] tag#1 CDB: Write(16) 8a 00 00 00 00 01 70 04 08 68 00 00 00 08 00 00


      This is a 8TB Seagate external USB 3.0 device apparently newer kernels use a module called "UAS" instead of "USB Storage" which causes issues as a lot of devices are not properly supported in UAS mode by the kernel driver.  The solution some say is to disable UAS specifically for your USB device but I'd rather just disable UAS altogether.   Solution blacklist UAS: *do not do this it does not work and just causes your USB 3.0........
  • Coolermaster CM Storm Enable LED Backlight in Fedora/Ubuntu/Mint Linux Howto - MB24 Keyboard and MS2K Mouse


    Just type the following in the bash/terminal shell to enable the blue LED light on the Coolermaster CM Storm keyboard: xset led 3 To make it automatic and permanent execute the following as root: echo "xset led 3" >> /etc/rc.local   This is a fairly nice gaming keyboard which I bought because I type very quickly and the cheap standard keyboards simply can't keep up!........
  • mencoder bmovl error vf_bmovl: Unknown command: ''. Ignoring.


    Based on this tutorial: http://www.linuxjournal.com/content/overlay-images-video-using-mplayer-and-mencoder mencoder -oac pcm -ovc raw -vf bmovl=0:0:tfifo -o $output $file vf_bmovl: Unknown command: ''. Ignoring.  ........
  • text to speech for Linux


    espeak - is horrible and sounds very old and robotic echo "hello there"|espeak #don't know how to use mbrola and plugins cicero jovie just seems to be a graphical interface to espeak There is also sbreader/sapi Google's Text To Speech Works Quite Well #!/bin/bash say() { local IFS=+;/usr/bin/mplayer -ao alsa -really-quiet -noconsolec........
  • Linux bash script how to generate a random password using /dev/urandom


    This command will generate a random password using all letters and numbers that is 20 characters wrong based on /dev/urandom (for the most truly random output). echo `< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-20};echo;`........
  • How to create openssl md5 password hash to use in /etc/shadow using bash


    Very useful in embedded and other non-standard deployments.  The above makes a random salt of 14 random characters from /dev/urandom (you can change the -14 to whatever number of characters you want for your salt). openssl passwd -1 -salt `< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-14};echo;` YourPassword Output: $1$eW-ScuyL$f/iKMJ5mbJ..7bSzvX6EO0    ........
  • bash how to check if a symlink exists as a file or directory


    To check if a file/directory is a symlink in bash: if [ -L /some/path/file ]; then echo "OK we're a symlink" fi   That's all there is to it.........
  • How to verify SSL SHA-1 Certificate Fingerprnit Signature of your mail/web server to avoid hijacking/man-in-the-middle attacks


    This is especially helpful if you run your own servers.  If you are presented with an error message or warning that the signature has changed or does not match the IP/domain you are connecting to you always want to verify manually. So your e-mail/web client will show you an SHA-1 fingerprint like this: "Could not verify this certificate because the issuer is unkown" or other reasons such as a mismatch in IP/domain. It will also show you........
  • mdadm frozen and doesn't realize array is dead/missing failed due to unplugged drives


    This was a surprising bug but I unplugged all drives for an array md127.  At first it was just 1 drive and mdadm seemed to notice this.  I unplugged the second drive taking the array offline but mdadm did not realize it was offline and still showed a non-existent disk as being part of it.  This created problems trying to unmount it or even to stop this array with mdadm freezing.  As for how to fix it I can only think of making sure you are not in a mounted path of........
  • if script bash check if socket file (mysql.sock) exists


    The "-S" switch is important as it works with sockets if you use "-f" it will not detect the socket file is there.   if [ ! -S "/var/lib/mysql/mysql.sock" ]; then  echo "Socket does not exist, restarting"  service mysqld restart fi........
  • bash count length of string and characters


    variable="abc hello" How do you count it (note blank/white space counts as a character too)? echo "${#variable}" 9........
  • fdisk wq causes hung process


    I created a new partition table on a newly plugged in device and it caused fdisk to hang (even force kill does not work).  It also may be a bad drive or some other issue because fdisk -l hangs after the first 2 HDDs (totaly of 8 HDDs on this system): [1232879.903596] INFO: task fdisk:27176 blocked for more than 120 seconds. [1232879.903607]       Tainted: P        &nbs........
  • iptables how to forward localhost port to remote public IP


    iptables -t nat -A OUTPUT -m addrtype --src-type LOCAL --dst-type LOCAL -p tcp --dport 3306 -j DNAT --to-destination ip.ip.ip.ip iptables -t nat -A POSTROUTING -m addrtype --src-type LOCAL --dst-type UNICAST -j MASQUERADE sysctl -w net.ipv4.conf.all.route_localnet=1 Make sure you substitute "ip.ip.ip.ip" for your real public IP and also the "--dport 3306" for the port you want to forward. Finally run the sysctl command and........
  • mcp55 NIC not working at boot on Centos 6.6-6.8


    forcedeth 0000:00:08.0: irq 25 for MSI/MSI-X forcedeth 0000:00:08.0: eth0: MSI enabled forcedeth 0000:00:08.0: eth0: no link during initialization ADDRCONF(NETDEV_UP): eth0: link is not ready forcedeth 0000:00:08.0: eth0: link up ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready Dec  1 18:21:32 box15 kernel: forcedeth: Reverse Engineered nForce ethernet driver. Version 0.64. Dec  1 18:21:32 box15 kernel........
  • OpenVZ mass ip update


    The file ipupdate.txt should look like this: ip.ip.ip.ip ctid while read -r; do ip=$REPLY setip=`echo $ip|awk '{print $1}'` ctid=`echo $ip|awk '{print $2}'` echo "vzctl set $ctid --ipadd $setip --save" vzctl set $ctid --ipadd $setip --save done < ipupdate.txt........
  • forcedeth MCP55 Nforce3600 Nvidia Network NIC Card Not working in Linux at 1gigabit speeds


    Now many people report this card simply not working in various Linux distros and kernels.  My issue is different, it always works at 100mbit (eg. plugged into a 100mbit switch) but no matter what 1000M/gigabit switch I would try, it would never work. The link would be up (the lights were on) and the OS detected the link as being up as well but it wouldn't work at all and could not pass data in or out (not even a ack/ping). There is one simple solution and command........
  • Linux how to enable and disable NCQ


    To disable NCQ in the Linux kernel (change sda to match your device). echo 1 > /sys/block/sda/device/queue_depth To enable NCQ (change sda to match your device). echo 31 > /sys/block/sda/device/queue_depth........
  • blocked for more than 120 seconds issues with iowait and timeout on Live Linux distribution while writing to physical disk


    This happened while an mdadm array was syncing, all access from writing a new blank file to opening a small .txt file was very slow:   [222117.312078] kjournald starting.  Commit interval 5 seconds [222117.685060] EXT3-fs (md0): using internal journal [222117.685096] EXT3-fs (md0): mounted filesystem with ordered data mode [222122.376847] kjournald starting.  Commit interval 5 seconds [222122.602825] EXT3-fs (md2): using internal jour........
  • Debian Linux Ubuntu Mint connect to pptp from terminal bash shell


    apt-get install pptp-linux echo "yourvpnusername * yourpasspass *" >> /etc/ppp/chap-secrets vi /etc/ppp/peers/provpnaccounts.com enter (ignore the lines): ============ pty "pptp server.provpnaccounts.com --nolaunchpppd" name testuser #remotename PPTP require-mppe-128 file /etc/ppp/options.pptp ==========........
  • vi Debian Linux Ubuntu Mint arrow key problem linux ssh bash shell terminal


    Debian/Ubuntu vi keyboard problem, up and down arrows do not work and instead make an A (Up), B (Down), C (Right) or D(Left). The working solution (you could also add the set nocompatible to /etc/vim/vimrc to make it system wide-will not be applied until reboot I believe): echo "set nocompatible" > ~/.vimrc some suggest entering this in vi but it did not work for me: :set term=cons25 The........
  • bash scripting for loop set number of iterations


    A handy trick in bash that can be adapted to many useful tasks: for i in {1..99}; do echo $i done 1 2.. 97 98 99 100 Another tricky is if you need a 0 in front of the first letters: for i in {1..12}; do if [ $i -lt 10 ]; then     i=0"$i" fi echo $i........
  • linux bash mass rename tool Centos/Debian/Ubuntu


    Say you have a bunch of files like this: file-01.jpg file-02.jpg ............... What if you want to mass rename them? the rename tool can work just like sed For Debian based distros: Note "file" is what we search for and "newname" is what we replace it with, so substitute according to your requirements. rename s/file/newname/ name-file-*.jpg For R........
  • bash script Get Model and Serial Number of All Hard Disks in Server on Linux


    for disk in `fdisk -l|grep "Disk /dev"|awk '{print $2}'|sed s/://g`; do echo "$disk" && smartctl -d ata -a "$disk" -T permissive|grep -iE 'Device Model:|Serial Number:' echo "---------------" done *Make sure you have smartctl from smartmon tools installed   Sample output: /dev/sdc Device Model:   ........
  • OpenVZ Install Guide Again / Quick Setup


    yum -y install wget wget -P /etc/yum.repos.d/ http://ftp.openvz.org/openvz.repo rpm --import http://ftp.openvz.org/RPM-GPG-Key-OpenVZ yum -y install vzkernel vzctl #enable ip_forward sed -i s/'net.ipv4.ip_forward = 0'/'net.ipv4.ip_forward = 1'/g /etc/sysctl.conf #all interfaces should not send redirects echo "net.ipv4.conf.default.send_redirects = 1" >> /etc/sysctl.conf echo "net.ipv4.co........
  • Centos yum mirror problem error "[Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found""


    [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found" The above happened when for some reason all the mirrors in my cache didn't have the files (some mirrors only keep the latest version of Centos). I tried to block them all but that didn't help because it seemed the mirrors were all hardcoded no matter what I tried. Here is how to fix it and reset your mirror list in Centos cd /var/cac........
  • bash script check if string contains text


    if [[ $variable = *windows* ]]; then echo "Our variable has windows" fi    ........
  • bash script how to do wildcard string comparisons or matching


    This is a feature that works very well in bash and is easy to do: *Remember you need the double brackets for this specific test even though a normal if would not require them variable="hi there" if [[ "$variable" = hi* ]]; then echo "yes it contains hi" fi........
  • bash script test if directory exists


    It's very simple test to see if the directory exists or not.  See the directory test in bash below: if [ -d /home/mydir ]; then echo "my directory exists" fi........
  • bash script check if file exists


    It is very simple and like this to test for the existence of file using bash scripting: if [ -f /etc/somefile ]; then echo "yes it exists" fi........
  • Linux disable firmware prevents NIC/Ethernet from working phy0 -> rt2x00lib_request_firmware: Error - Failed to request Firmware.


    [   17.208336] tg3 0000:08:00.0: eth0: Link is up at 1000 Mbps, full duplex [   17.210194] tg3 0000:08:00.0: eth0: Flow control is on for TX and on for RX [   76.000065] phy0 -> rt2x00lib_request_firmware: Error - Failed to request Firmware. [   76.002332] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready [   86.736004] eth0: no IPv6 routers present [  148.960038] phy0 -> rt2x00lib_request_fi........
  • bash shellshock how to manually patch when there is no update for Centos/Debian/Ubuntu/Fedora


    wget http://ftp.gnu.org/gnu/bash/bash-4.3.tar.gz tar xzvf bash-4.3.tar.gz cd bash-4.3/ wget --no-directories --level 1 --recursive http://ftp.gnu.org/gnu/bash/bash-4.3-patches/ for patch in `ls bash43-*|grep -v .sig$`; do echo applying "$patch" patch -p0 < $patch done ./configure;make;make install #it will install to /usr/bin/bash but if your bash is somewhere else you need to overwrite the old one.........
  • phpBB create new email hash manually when modifying or adding user manually directly through MySQL


    Many may ask why would you need to do this?  When upgrading from phpBB 2 to 3 the conversion does not keep the admin user you create.  If your old admin user has an email address associated that no longer works or is accessible this makes it impossible to reset the admin password. Some may just say "I'll just manually edit the e-mail address" but it won't work and phpBB will fail to find that user if you don't update the "user_email_hash" field but how do........
  • drbd won't sync 8.3.13 on OpenVZ kernel


    <p>I used the matching 8.3.13 utilities and it didn't work but strangely the newer 8.3.16 which makes DRBD complain works just fine.</p> <p>GIT-hash: 83ca112086600faacab2f157bc5a9324f7bd7f77 build by root@sighted, 2012-10-09 12:47:51<br /> &nbsp;0: cs:SyncSource ro:Secondary/Primary ds:UpToDate/Inconsistent A r-----<br /> &nbsp;&nbsp;&nbsp; ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:5236960<br /> &nbsp;&nbsp;&am........
  • How to script fdisk in Linux bash


    (echo n; echo p; echo 1; echo 1; echo; echo wq) | fdisk /dev/sdb The above would make a new partition 1 on /dev/sdb and save the changes to disk, you can of course make changes to do almost anything in fdisk.........
  • Howto Convert Xen Image to KVM


    #count=10000 makes an image of 10000MB make sure your image is at least the same as your existing dd if=/dev/zero of=yourimage.img bs=1M count=10000 # losetup -fv newimage.raw # fdisk -cu /dev/loop0 # kpartx -a /dev/loop0 # dd if=<xenimage> of=/dev/mapper/loop0p1 # e2fsck -f /dev/mapper/loop0p1 # resize2fs /dev/mapper/loop0p1 # a lot of guides tell you to edit /etc/fst........
  • Centos Howto Upgrade to PHP 5.3 from 5.2


    It's not as simple as "yum install" as you can see below and it doesn't stop there.  yum install php53 Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * rpmforge: mirror.us.leaseweb.net  * extras: centos.mirror.rafal.ca  * updates: centos.mirror.nexicom.net  * base: centos.mirror.nexicom.net  * addons: centos.mirror.nexicom.net Setting up Install Process........
  • [emerg] (28)No space left on device: Couldn't create accept lock (/etc/httpd/logs/accept.lock.15449) (5) solution


    [Wed Jan 08 18:50:07 2014] [emerg] (28)No space left on device: Couldn't create accept lock (/etc/httpd/logs/accept.lock.15449) (5) This may happen when trying to restart Apache and you find it dies right after starting and check /var/log/httpd/error_logs. What is the cause of this? You could be out of disk space (if you're not then see #2 and below) You're out of Semaphores, you need to kill all the old ones.........
  • Update wordpress script


    Requirements: 1.) Enter your root wordpress directory. 2.) Download the latest wordpress.zip to it. #backup your current files just in case cp -a . wp-current-bk`date +%Y%m%d` unzip wordpress-3.7.1.zip rm -rf wp-includes rm -rf wp-admin echo y|cp -a wordpress/wp-includes . echo y|cp -a wordpress/wp-admin . echo y|cp -a wordpress/wp-content/* wp-content echo y|cp wordpress/* .........
  • 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`........
  • mdadm increase recovery sync/resync speed slow solution/fix


    The units in echo are kB as in kilobyte. Setting a high sync speed echo 120000 >/proc/sys/dev/raid/speed_limit_min This will increase the speed, note that sometimes a rebuild is slow due to current disk activity/iowait. If that is not the cause then you may have a hardware issue (controller, cable or a bad drive). Setting a lower sync speed echo 1200 >/proc/sys/dev/raid/speed_limit_max........
  • bash check that file is not blank/zero bytes in size


    if [ ! -s /path/to/file ]; then echo "file is blank or zero bytes" fi Use -s to check if it's larger than 0 bytes, I like to use the ! (not) operator to do this as shown above.........
  • pxe-32 tftp open timeout


    pxe-32 tftp open timeout   The solution was to enable tftp in xinetd with "chkconfig tftp on". See the troubleshooting below:   chkconfig --list NetworkManager     0:off    1:off    2:off    3:off    4:off    5:off    6:off acpid              0:off&n........
  • Bash weird variable whitespace missing when echoing printing


    Bash weird variable whitespace missing var=`cat tlds.csv|grep .ca,` # echo "var=:$var:" :ar=:.ca,Canada Why is the v missing in the last line? It should be :var=:.ca,Canada instead of :ar=:.ca,Canada I noticed a problem with the file with doing a "cat -v" on it. Here's the issue, the file contains carat M ^M: .vg,British Virgin Island........
  • bash script howto use heredocand assign to a variable and write to a file


    <p><code>zonetemplate=$(cat &lt;&lt;</code></p> <p><code>info here<br /> </code></p> <p><code>other things here<br /> </code></p> <p><code>SETVAR)</code><br /> &nbsp;</p> <p>The above is all you need, note that if you have variables you need to escape the $ with a so you then have $ otherwise the variables will be substituted which is probably often not what........
  • charat in PHP convert non-English characters into code


    This is basically URL decoding to the decimal code but nothing in PHP works how you'd expect it. Here are online tools to verify and check your work, it's important when querying databases with non-English characters: http://yehg.net/encoding/index.php# http://meyerweb.com/eric/tools/dencoder/ http://www.codetable.net/decimal/65398 Japanese: http://symbolcodes.tlt.psu.edu/bylanguage/japanesechartkatakana.html Charat code for PHP:........
  • bash how to read a single line or filenames with spaces solution


    This happens all the time, you are reading from a textfile which has spaces eg: datainfo 00 datainfo 11 If you do loop on it like this: for info in `cat $file`; do   echo "info=$info" done It will treat datainfo and 00 as two separate lines: info=datainfo info=00 Obviously that's not what we want and there are many weird solutions in bash bu........
  • bash random number


    $[ ( $RANDOM % 5000 ) + 20 ] echo "$[ (........
  • bash for loop script for a specified number of times example


    for entity in {1..20}; do echo "entity=entity" done The above will loop 20 times, you could also do {2..50} etc... for entity in {0..10..5}; do echo "entity=entity" done The above will loop 10 times but will start from 0 and increment by 5 each time.........
  • How to log all PHP based E-mails for abuse


    Step #1 - Create Wrapper Script vi /usr/local/bin/phpsendmail #!/usr/bin/php <?php //changed by realtechtalk.com to make the log readable /**   This script is a sendmail wrapper for php to log calls of the php mail() function.   Author: Till Brehm, www.ispconfig.org   (Hopefully) secured by David Goodwin <david @ _palepurple_.co.uk> */........
  • Thunderbird How-To Copy/Backup/Restore Accounts and Settings to Another Computer


    The best way is to use rsync, I've set it up so it doesn't copy unnecessary files, or at least ones I'm sure aren't needed. Here is the rsync command I used (adapt to your specific Thunderbird profile location): rsync -hazv user@remotehost.com:/home/user/.thunderbird/sbrer.default/* /home/user/.thunderbird/4nyb0.default/ --exclude=global* --exclude=Cache --exclude=ImapMail --exclude=Mail This is a great way to get your e-mail accounts going on a new c........
  • Disable SELinux How To Tutorial Solution


    Here is a quick script that works on most Centos versions to disable the virus/SELinux from blocking basic functionality. The first echo 0 statement disables SELinux instantly but it will still be enabled on reboot. The second line disables it permanently. #!/bin/bash #disable SELinux Immediately echo 0 > /selinux/enforce #disable SELinux Permanently sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config........
  • ip_conntrack: table full, dropping packet. solution for Linux RHEL/Centos/Debian


    ip_conntrack: table full, dropping packet. A lot of clients I've seen have this issue, it really seems the default level is way too small.  Once this connection tracking table becomes full then packets get dropped which is obviously a bad thing. One thing to be mindful of though is that 350 bytes of memory are used per entry so there is some justification for not keeping it too high.  However, if you have multiple servers running or high traffic daemons........
  • bash script remove non-printable special characters/white space


    In bash you test like this for problems that can be caused by non-printable characters since if you don't know how to identify it because it basically breaks your script. echo "url=$url" should print something like this normally if you have properly formatted input/text: url=::http://someaddress.com:: But if you have some weird hidden characters (not visible in a text editor of any sort you'll get something like this ::l=::http://s........
  • Skype Linux/Ubuntu Sound Echo/Distortion Poor Quality Problem Fix Solution


    This was very annoying but has a simple fix, I had an echo and the voice quality was absolutely horrible (it sounded like tin cans under water) if that helps describe it.  It was extremely distorted. The simple Skype sound quality solution Go to "Options" -> "Sound Devices" Disable the "Allow Skype to automatically set my mixer levels" After doing this the sound qua........
  • Centos Solution to "Warning: Unable to open /dev/fd0 read-write (Read-only file system). /dev/fd0 has been opened read-only."


    Warning: Unable to open /dev/fd0 read-write (Read-only file system).  /dev/fd0 has been opened read-only. That's a very annoying error, it's simply because Centos for some reason thinks it's wise to load the "floppy" kernel module, who has a floppy drive?  I haven't seen or used a floppy for over 12 years! It's more than just annoying, if you probe the drives attached to your system, eg. with grub or partprobe, it keeps trying to locate a flopp........
  • Linux High IOWAIT updatedb can't be killed and crash with mdadm


    high IO wait   424 root      39  19  1900  848  552 D  0.0  0.0   0:00.91 updatedb root       424  0.0  0.0   1900   848 ?        DN   Mar11   0:00 /usr/bin/updatedb -f sysfs?rootfs?bdev?proc?cpuset?binfmt_misc?debugfs?sockfs?usbfs?pipefs?anon_inodefs?futexfs?tmpfs?inotifyfs?eventp........
  • 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........
  • Thunderbird/MBOX to IMAP/Maildir migration done easy with mb2md


    Convert MBOX Mail files into Maildir using Linux *You need perl an the TimeDate module Get the free Perl script mb2md from the project/author's site: wget http://batleth.sapienti-sat.org/projects/mb2md/mb2md-3.20.pl.gz gunzip mb2md-3.20.pl.gz #remember you need timedate or you'll get this error: ./mb2md-3.20.pl Can't locate........
  • CPU #1 not responding - cannot use it.


    I think this will be useful to others because I have a server that kept crashing mysteriously during intense disk usage/RAID checks.  It would only crash during the weekly RAID integrity check. Then I noticed during a reboot that not all CPUs were being brought up, as a result this actually creates much higher temperatures with the output I got from sensors, just booting the system produced higher than normal temperatures. You can imagine that a full blown RAID check........
  • updatedb/mdadm caused a kernel panic?


    Jan 16 04:02:03 centosbox syslogd 1.4.1: restart. Jan 16 04:07:34 centosbox kernel: INFO: task updatedb:20771 blocked for more than 300 seconds. Jan 16 04:07:34 centosbox kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Jan 16 04:07:34 centosbox kernel: updatedb      D F78BE050  6476 20771  20766                &n........
  • Installing Webmin & Enabling SSL


    Webmin Setup Centos 5: wget http://downloads.sourceforge.net/project/webadmin/webmin/1.530/webmin-1.530-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.com%2Fstandard.html&ts=1294339690&use_mirror=surfnet [1] 24229 [2] 24230 [root@host ~]# --2011-01-06 21:48:20--  http://downloads.sourceforge.net/project/webadmin/webmin/1.530/webmin-1.530-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.com%2Fstandard.html Resolving downloads.sourceforge.net... 216.34.181.........
  • mdadm/md-check how to check array integrity without rebuilding


    This doesn't seem to be widely known (maybe it's in some documentation that none of us read though) but there's an easy way to check the integrity of any mdadm array: sudo echo check > /sys/block/md0/md/sync_action -bash: /sys/block/md0/md/sync_action: Permission denied sudo will never work, this only works as root since echo is not actually a binary/command.  It is built-into bash. /sys/devices/virtu........
  • 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........
  • yum in Centos 5/Xen halts and exits suddenly


    yum exits in the middle The problem is this VPS seems to be an OpenVZ template from HyperVM.  The only way to make it work was to disable i386 packages since this was an x64 kernel.  That shouldn't be necessary but it was the only way to make yum stop quitting after the first package or two.  I couldn't find any issue by checking the logs either. echo y|yum install vim-minimal telnet expect jwhois net-tools slocate iptables elinks gawk L........
  • yum error with some versions of Centos Refusing to automatically import keys when running unattended. Use "-y" to override.


    Refusing to automatically import keys when running unattended. Use "-y" to override. When using echo y|yum install gcc Fix with rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY*........
  • How to chroot properly into your OS/distro


    From a LiveCD or if you're doing something like converting your non-RAID install to mdadm here's how you would chroot properly (you have to mount your proc, sys and dev on the running system/LiveCD to your chroot environment if you want things to work right, especially if you need to run update-initramfs due to a driver change etc..) *replace "path" with your mount/chroot path mount -o bind /proc /mnt/path/proc mount -o bind /dev/ mnt/pa........
  • Buffer I/O error on device fd0, logical block 0


    Virtually no system has a floppy disk drive anymore but you will often find your Linux distribution insists that you do or should have one :) The solution is to remove the floppy module and prevent it from loading on the next reboot. rmmod floppy Centos/RHEL echo "blacklist floppy" >> /etc/modprobe.d/blacklist Debian/Ubuntu sudo echo "blackli........
  • DirectAdmin Install Webalizer Stats


    I can't believe it comes without any sort of stats built-in and they don't make it easy to find out how to integrate it. I downloaded the following: wget -O /usr/bin/webalizer http://files.directadmin.com/services/es_5.3/webalizer chmod 755 /usr/bin/webalizer echo "action=tally&value=all" >> /usr/local/directadmin/data/task.queue........
  • SSH Automatic/Passwordless Logon - Setup Public Key Encryption In Single Command


    This is a very simple solution, but most guides out there make you login twice (once to scp the key) and once to put the key in authorized_keys.  There's no need for that.  If you don't already have a ~/.ssh/id_rsa.pub just type "ssh-keygen -t rsa" and keep hitting enter until it's done :) Just use this code to easily enable passwordless login with SSHD key=`cat ~/.ssh/id_rsa.pub`;ssh user@192.168.5.25 "echo $key >> ~/.ssh/auth........
  • Linux AHCI Hotswap Tips - Remember To Reread The Partition Table WITHOUT rebooting


    From the package "parted" you can use the command "partprobe" to re-read the partition table.  I really hate rebooting, and that's what I loved to hear about AHCI motherboards, that they allow hotswap so you don't have to reboot.  But that's only as good as the OS, if the OS does not reload the partition table you won't be able to do anything with that new drive you attached without rebooting.  Yes, even without re-reading the partiton table Linux will........
  • PHP cannot access /usr/bin/openssl


    PHP cannot access /usr/bin/opensslI have verified the username that runs the process is able to access /usr/bin/openssl and it does exist but the PHP script is saying it doesn't exist: [code:1:1fd0f3abbe] if (!file_exists($OPENSSL)) { //echo "ERROR: OPENSSL $OPENSSL not foundn"; }[/code:1:1fd0f3abbe] I don't get itI can clearly see the contents of /usr/bin by using the PHP system fu........
  • Change default shell


    Change default shellJust echo this at your command line (in this case I chose bash since I prefer the bash shell) this way it will be the default when you login again [code:1:71e2834907]chsh -s bash[/code:1:71e2834907]........
  • Bash Script Info


    Bash Script Infohttp://www.faqs.org/docs/Linux-HOWTO/Bash-Prog-Intro-HOWTO.html#ss10.5 http://www.scit.wlv.ac.uk/~jphb/spos/notes/shell/shell5.html http://quong.best.vwh.net/shellin20/#LtohTOCentry-41 http://www.cactus.org/~dak/shellscript.html http://db.ilug-bom.org.in/Documentation/abs-guide/ http://pegasus.rutgers.edu/~elflord/unix/bash-tute.html http://heather.cs.ucdavis.edu/~matloff/UnixAndC/Unix/CShellII.html Since bash i........
  • Bash Scripting Variable Scope Using Piped While Loop


    I've been struggling with this for awhile, wondering why all of my variables are null.  I just realized the variables disappear after leaving this while loop. Note that I'm piping to the while loop which makes a subshell I believe which is the cause of the issue:   echo "$accounts"|while read thisline; do    somevariable="some value"    (( ++counter )) done At all costs you ne........
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