/ - 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........
  • 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........
  • VMWare ESXi 6.7 SSH/PowerShell CLI Commands


    [root@localhost:~] BootModuleConfig.sh          echo                         host-ind                     nfcd                   ........
  • OpenVPN auth-user-pass-verify ENV script error


    Starting with newer versions of OpenVPN I believe 2.2+ you need to have "script-security 3" set or you can't execute a third party script. Prior to that you could also use the auth-user-pass-verify like this: auth-user-pass-verify ./validate.pl "$username $password $ip" via-env Options error: the --auth-user-pass-verify directive should have at most 2 parameters.  To pass a list of arguments as one of the paramete........
  • Database Error One or more of the WHMCS database tables appear to be either missing or corrupted. Please check and repair. - WHMCS Solution


    Database Error One or more of the WHMCS database tables appear to be either missing or corrupted. Please check and repair. This error can be misleading especially if you know you are using a known good backup or restoration of the WHMCS database.  The error can also be that the user lacks permissions to read and write to the database. To check to this in MySQL shell: GRANT read,write to dbusername@localhost on dbna........
  • 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........
  • Ubuntu/Debian/Linux won't boot and drops to Busybox shell after cloning HDD with dd


    I don't recall having this issue in the distant past but nowadays at least Debian seems to be very picky about this. I used dd to copy one hard drive to another and tried booting it.  Everything seemed fine with grub working but each time it would drop to the busybox shell.  There is no particular error so this is misleading. Normally the first things you would check are to make sure your fstab is correct (that the UUID is correct) and that you've updated grub.&........
  • kdenlive - No LADSPA plugins were found! Check your LADSPA_PATH environment variable. [producer_xml] failed to load transition "qtblend"


    This happens if you are running a kdenlive script from the shell of a remote machine without using SSH "-X" forwarding and it will also cause any areas where you write text to be a white screen for that duration.   melt FusionFestival.kdenlive No LADSPA plugins were found! Check your LADSPA_PATH environment variable. [producer_xml] failed to load transition "qtblend" [producer_xml] failed to load transition &q........
  • Centos/Linux Bash Script Warning when exiting/logging out of bash/shell/terminal for scripts running in the background


    This is mainly the case on Centos but applies to other distros and situations.  If you are running programs in the background with the &, at least in Centos it is usually not honored and if you quit or are disconnected the backgrounded programs will be sent sighup and be shut down.  The simplest way around this instead of using & is to start any programs or commands with "nohup" Eg. nohup yourscript.sh........
  • 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!........
  • Linux how to whois query other gTLDs such as .club solution


    whois in Linux is incredibly out of date and does not seem to recognize most new TLDs domains, but there is a quick and easy tip/hack/tweak for this. An example of new TLD's site as .review .site .club whois somesite.club No whois server is known for this kind of object.   bash to the rescue Now I did try to apply this in .bashrc but DO NOT!  I think the * wil........
  • Linux How To Recover Partition Table from Kernel and Restore Centos/Debian etc..


    We've all done this at some point, you work on the wrong shell window and this was my first time making this mistake but I deleted a partition table in fdisk, recreated it and saved it with "wq" and even ran partprobe!  If you haven't rebooted yet then you can still recover your partition table, otherwise you're in big trouble. Fortunately since it was a live system and in use the kernel still had to use the old table like below:........
  • Script runs fine from shell but not from cron job in Linux/Unix Debian/Ubuntu/Mint/Centos


    Usually the cause is inexplicable because some things just don't work correctly even when calling all commands by their full path. Usually adding the following to your crontab file at the top will fix/solve the issue: SHELL=/bin/sh PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin  ........
  • Apache SSL Reverse Proxy Very Slow Solution


    This is a simple fix but not a simple problem and it still doesn't make sense to me. But in a nutshell if your target proxy server works fast when accessing directly over SSL then this may be your issue. It seems SSL does not play nicely when the target proxy destination/host has a riduculously long key (such as 8192 bits long).  Now this is normally not a problem, in fact the target server could be accessed with hardly any delay directly despite such a long key.........
  • Linksys E2500 DD-WRT Upgrade Instructions and Enabling 5ghz with Tomato Firmware


    1.) Flash directly to this file: http://tomato.groov.pl/download/K26RT-N/build5x-132-EN/Linksys%20E-series/tomato-E2500-NVRAM60K-1.28.RT-N5x-MIPSR2-132-Max.zip *I was never able to get the larger "Mega" file to work, at least not initially so I recommend the file above. To enable 5ghz I had to do the "Clear NVRAM" Option before it was shown. 2.) Or if you don't need 5ghz (most devices do not support it and cannot........
  • 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........
  • How to scp transfer a file in Linux with spaces


    Say you have a path like this "/some/path/here with spaces/".  If you try to transfer it you will get a message along the lines of: scp -rp 192.168.0.12:"/some/path/here space/" . scp: /some/path/here: No such file or directory scp: space: No such file or directory You can escape each space but what a pain that is especially if you have multiple spaces in the path. The simplest way is to use the follow........
  • Disable linux bash proxy ENV export variable


    if you type Export and see something like this:   declare -x all_proxy="socks://127.0.0.1:22000/" Most sites assume and tell you to check your .bashrc or /etc/profile /etc/bash.bashrc which may not apply if you've unknowingly or forgot that you setup a proxy from your GUI such as Gnome. To check in Gnome if you have a permanent proxy do the following: System -> Settings -> Network Proxy........
  • 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.........
  • Setting Ulimit


    I never found a solution to do it live (nothing worked that I found) so it looks like a relogin is required. Check your maximum file limit  cat /proc/sys/fs/file-max 824460   This is different than your actual's user limit which you'll see below ulimit -n 1024 Try and set it higher but it won't work ulimit -n 65000........
  • cPanel VPS Server Cannot Login as root


    I was worried the server was hacked, I was logged in already as root but couldn't login to CPanel or a new SSH session.  I even reset the password from the shell and it did not work still. The reason is CPanel Hulk, it detected a brute-force attack so it locked down the root account entirely even from the correct password.  According to cPanel the best way around this is to whitelist your IP.........
  • Android how to copy rsync binary to main system for use in shell/ssh


    Install rsync4randroid and in the shell/ssh do this: ln -s /data/data/eu.kowalczuk.rsync4android/files/rsync /system/xbin/rsync........
  • Unixbench Testing


    The first is a dual CPU AMD Opteron 2373EE (4 cores x 2) and I think it did bad because it has some old 250GB SATAs which can only do about 65 MB/s max sequential reads.  I think it should have blown away the second (AMD X4 640 Quad Core).   [root@fs12home unixbench-4.1.0-wht-2]# ./Run make all make[1]: Entering directory `/root/unixbench-4.1.0-wht-2' Checking distribution of files ./pgms  exists ./src  exists........
  • 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........
  • 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> */........
  • how to exit xen console session from xm


    It sure is annoying when you connect to the console using xm and it locks your shell session. It doesn't really, you just need to know it is "Ctrl + ]" to exit it. Once again to exit an xm console session, press Ctrl + ]........
  • vi disable color syntax highlighting/can't read syntax highlighting


    Within vi if you can't exit /etc/vim/vimrc you can type :syntax off And to turn it back on: :syntax on Many of us have a dark/black background in our terminal/shell making the default syntax unreadable, the solution is to either turn off syntax highlighting with :syntax off or to enable a special option in /etc/vim/vimrc Edit /etc/vim/vimrc The "syntax on" enables the highligh........
  • Kernel/make compilation time and how to improve compile times/compile the Linux kernel faster without hardware upgrades


    I thought only a faster CPU and SSD would help but I already have a Quad-Core CPU and it wasn't being maxed out.  The actual tests were performed on an AMD-V enabled 128MB dual core VMWare container though. There is a flag that can be passed to make in order to start multiple threads, by specifying 4 threads I was able to reduce the whole kernel compilation time from scratch by about 50%! (65minutes vs 31minutes!).  *Yes I did do a make clean before each co........
  • iPhone 3G/3GS/4 Undelete Photos/Videos Datarecovery


    I found this technique listed in many places which shows you how to use a common Linux tool "dd" to dump the raw partition of your iPhone. I give credit to this site for showing me the correct way to dd from the iPhone, I never thought to try it in the other direction: http://log.ijulien.com/post/182804914/iphone-3gs-data-recovery Requirements 1.) Jailbreak your........
  • encrypt bash scripts to hide source code


    http://www.datsi.fi.upm.es/~frosal/ SHC is a program written by the author above that does just that, it's a great little tool to have. Some have said it isn't exactly encrypting the code but just making it hard to read by obfuscating the code. There was also a good discussion about that here:........
  • 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.........
  • Wine stopped working/won't work Solution


    After an upgrade wine wouldn't open anything, not even the pre-installed notepad. There are no wine logs and nothing is mentioned in any standard log file about why. I finally decided to run wine from the shell and see what's going on: wine client error:0: version mismatch 398/402. Your wineserver binary was not upgraded correctly, or you have an older one somewhere in your PATH. Or maybe the wrong wineserver is still running?........
  • Nautilus/GNOME File Manager handy list of extensions


    nautilus-gksu - privilege granting extension for nautilus using gksu nautilus-sendto - integrates Evolution and Pidgin into the Nautilus file manager nautilus-share - Nautilus extension to share folder using Samba nautilus-actions - nautilus extension to configure programs to launch nautilus-bzr - Bazaar (bzr) integration for nautilus nautilus-cd-burner - CD Burning front-end for Nautilus nautilus-clamscan - Antivirus scanning for Nautilus n........
  • jailkit for chroot ssh account security tutorial and fix for error


    This was done on Centos but I think it's easier on Debian machines, the paths that it is set to use are tailored towards Debian, so there is some fiddling that needs to be done on Centos. This is for chrooting ssh, but jailkit has other uses than just SSH jails but I won't cover them in this writeup. 1. Install jailkit yum install jailkit 2. Setup Jail Home mkdir /home/jail chown root:root /home/ja........
  • Unixbench Score on Core i5 750 with OpenVZ Kernel vs Xen/Openvz


    This was unbelievable how much the Xen kernel slows things down, keep in mind both tests were done on the hostnode, one was with the Openvz-Xen hybrid kernel and the other was just OpenVZ.  You can see the performance difference is nearly 300% better when not using the Xen kernel. OpenVZ-Xen Kernel Test Results (I was wondering what was wrong/so slow with my Core i5!)    #    #  #    #  #  #  &n........
  • 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........
  • email2fax and Asterisk to do eFaxing


    It's basically free bash shell script available from: http://wpkg.org/email2fax/index.php/Main_Page Make sure you have the required tools: libtiff ghostscript mpack/munpack Where you can e-mail your Asterisk box and it will fax it to the phone number in the subject line.  The good news ends there, it is fairly undocumented and buggy. Take for example how the documentation mentions you can invoke from the com........
  • Picking an FTPD (vsftpd) Server in Linux Centos/Debian


    I decided on using yum to help me decide even though I normaly use proftpd I decided to see what else I could find. yum search ftp Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * rpmforge: ftp-stud.fht-esslingen.de  * base: mirrors.netdna.com  * updates: updates.interworx.info  * addons: yum.singlehop.com  * extras: mirrors.netdna.com rpmforge   ........
  • Compaq V2405CA Laptop - Unixbench Performance Test


    Here are the results, it is Sempron 3000+ AMD Mobile, 500Gig HDD, 512MB RAM with shared ATI Radeon graphics.      #    #  #    #  #  #    #          #####   ######  #    #   ####   #    #    #    #  ##   #  #   #  #&nb........
  • 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]........
  • Backup Shell Script


    Backup Shell Script[quote:aaa4b0b165]#!/bin/sh date=`date -I` mysqldump --all-databases | gzip > /var/backup/backup-$date.sql.gz [/quote:aaa4b0b165] Something like that could be useful as a cronjob to locally or remotely backup your databases........
  • 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........
  • Basic Port Listing


    Basic Port ListingHopefully someone finds this useful or at least interesting. http://www.sans.org/top20/#u9 Name Port Protocol Description Small services <20 tcp/udp small services FTP 21 tcp file transfer SSH 22 tcp login service TELNET 23 tcp login service SMTP 25 tcp mail TIME 37 tcp/udp time synchronization WINS 42 tcp/udp WINS replication DNS 53 udp naming service........
  • gnuCash - Alternative to Quickbooks/Quicken and other COTS accounting software.


    gnuCash is available for all main platforms, Linux/Unix, MacOS (FreeBSD anyway), and Windows. You can download gnuCash free from here. It does seem to be fairly full featured and somewhat straight forward, but like so many programs it is missing a few key features or things don't work quite right. It doesn't support importation of CSV files, which is a big minus.  And the developers rather than wanting to add support have just dec........
  • Unixbench Score with Glusterfs/Openvz & Quad Core Xeon - Updated with GlusterFS 2.0.8


    You might remember my original GluserFS/OpenVZ benchmark which produced a horrible 29.8 This is the exact same system, but using the latest 2.0.8 (with some small files patch which speeds up performance) you can see it is about 25% faster. I also haven't tuned my config files at all, but there are some settings that should increase performance on small files which I believe i........
  • Unixbench Score with Glusterfs/Openvz & Quad Core Xeon


    This is very disappointing since GlusterFS markets itself as a solution to deploy VPS servers on.  On the HN itself I get a Unixbench of about 360. I'm also using an SSH tunnel to secure the communications, but even before that, things seemed very slow.        #    #  #    #  #  #    #          #####&n........
  • Linux/Unix Open SSH Login Without Password Key Exchange including Debian, Redhat, Fedora, Ubuntu, BSD etc..


    In those 4 simple commands you can setup mutual key exchange between two sshservers by using a single login shell session and single window. *Just change the IP address examples of (10.10.0.2) to the target of your mutual key exchange.  It doesn't matter if the server is on a LAN or WAN (well unless the server is behind a firewall and you cannot SSH into it).........
  • Linux Bash Shell Cannot/Can't View File That Starts With - Dash ?


    I was getting really annoyed with this, I used full quotes around the filename and vi, cat, less all thought I was trying to pass the dash in the filename as an argument. I didn't realize that all you have to do is just put a dash dash "--" in front. Here's an example: cat -- "-etc-glusterfs-glusterfsd.vol.log" Without the -- you get: cat: invalid option -- c Try `cat --help' for more information. I h........
  • 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........
  • Weird characters in Linux putty shell


    I used to get all kinds of weird annoying characters like "â" during compilation with gcc especially. example: dmg2img.c:456: error: âBZ_OKâ undeclared (first use in this function) dmg2img.c:471: warning: implicit declaration of function âBZ2_bzCompressEndâ dmg2img.c:482: warning: implicit declaration of function âBZ2_bzDecompressâ dmg2img.c:484: error: âBZ_PARAM_ERRORâ undecl........
  • BASH script error "((: 08: value too great for base (error token is "08")"


    ((: 08: value too great for base (error token is "08") Here is the code that caused it for ((track=1;track <= $number_of_tracks;track+=1));do Also in each iteration "track" is padding with zeros using: track=`printf "%02d" $track` It doesn't happen until you pass 8 to it, if you pass 1,2,3,4,5,6 or 7 it works fine.  I read this is because it sees these numbers as octal numbers (it as in many progamm........
  • 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........
  • SSH Problem User username from 127.0.0.1 not allowed because not listed in AllowUsers


    User username from 127.0.0.1 not allowed because not listed in AllowUsers What's going on?  The user was created properly, it has been defined as having a shell entry and the entry for /etc/passwd and /etc/shadow is set just fine. This is a new and very smart/secure feature of SSHD.  It is simple and yet effective, but also very annoying if you didn't know about it being implemented and that hand editing of /etc/ssh/sshd_config is required to allow a newly add........
  • 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