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


    [root@localhost:~] BootModuleConfig.sh          echo                         host-ind                     nfcd                   ........
  • Mozilla Firefox Address Bar History Not Working places.sqlite corruption solution database repair


    Here is the only solution I found that works in Firefox: *Note you could basically just copy all of the commands in bold (the rest just shows the output)   Install sqlite3 sqlite3 places.sqlite sqlite> .clone places.sqlite-fixed moz_places... done moz_historyvisits... done moz_inputhistory..........
  • mysql how to reset passwords with a few commands


    The commands below will help you reset any mysql user password. use mysql; update user set password=PASSWORD('thenewpass') where User='theusername'; flush privileges;   The first line says to use the "mysql" database which contains all the user info. the second update line sets the new password "thenewpass" for the u........
  • M2Crypto.SSL.Checker.WrongHost: Peer certificate subjectAltName does not match host, expected fedora-archive.ip-connect.vn.ua, got DNS:mirror.ip-connect.vn.ua


    You are using Centos 5 which is deprecated so nothing in yum will work until you follow this post to use the vault: http://realtechtalk.com/Centos_59_Working_Vault_Repo_file-1921-articles yum update Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile  * epel: fedora-archive.ip-connect.vn.ua Traceback........
  • 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........
  • Track 01: 34 of 1726 MB written (fifo 100%) [buf 99%] 3.6x.Errno: 5 (Input/output error), write_g1 scsi sendcmd: cmd timeout after 1.897 (40) s CDB: 2A 00 00 00 44 A9 00 00 1F 00 resid: 6144 cmd finished after 1.897s timeout 40s write track da


    These errors believe it or not are simply because of not being the root user or running with sudo! However if you didn't know to try as root you'd think there was a problem with your burner or disc  Essentially it looks like without root you cannot send the required scsi commands to continue writing.  I think cdrecord should have built-in tests or safeguards to see if it has the permissions to run the required commands. I guess for more advanced users the idea is simila........
  • OpenVZ Error: Failed to load 2nd level quota solution


    Syncing private Live migrating container... Syncing 2nd level quota 11000: invalid option -- F Usage: vzdqload quotaid [-c file] commands Loads user/group qouta information from stdin into quota file.     -c file    use given quota file Commands specify what user/group information to load:     -G    grace time     -U    disk limits........
  • 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  ........
  • How to modify HTML/Themeforest Themes to work in any path statically using unix/linux's sed command


    For themes and custom CMS setups, the typical HTML theme is not ready to go at all but here are some common sed commands (search and replace that will get most of them working without breaking as you'd expect). The problem is that often the theme directory will be separate from the content and this will break the relative paths that these themes use. sed -i s/'href="'/'href="/themes/yourtheme/'/g index.html sed -i s/'src="'/'src="/themes/y........
  • SAS2008 LSI 9200-E Linux Upgrade Flash Firmware with sas2flash


    Download from here http://www.avagotech.com/products/server-storage/host-bus-adapters/sas-9200-8e#downloads   sudo Installer_P20_for_Linux/sas2flash_linux_i686_x86-64_rel/sas2flash -listall LSI Corporation SAS2 Flash Utility Version 20.00.00.00 (2014.09.18) Copyright (c) 2008-2014 LSI Corporation. All rights reserved   &nbs........
  • Directadmin Install Error Cannot find /usr/include/openssl/ssl.h. Did you run the pre-install commands?


    Cannot find /usr/include/openssl/ssl.h. Did you run the pre-install commands? http://help.directadmin.com/item.php?id=354 yum -y install openssl*........
  • Dell SAS 6/ir Cards are just LSi 1068E cards


    02:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1068E PCI-Express Fusion-MPT SAS (rev 08) 03:00.0 SCSI storage controller: LSI Logic / Symbios Logic SAS1068E PCI-Express Fusion-MPT SAS (rev 08) Basically these cards are a stripped-down version of Dell Perc 6/i only  they (SAS 6/ir) support JBOD. The Dell Perc 6/i are basically useless because it doesn't have JBOD support and requires software or BIOS commands to add or remove........
  • MySQL Allows blank user with no password to login


    I just realized I have some blank users which I deleted but I can still login to this dummy account without a password for some reason.   mysql -u -p Welcome to the MySQL monitor.  Commands end with ; or g. Your MySQL connection id is 5 Server version: 5.1.69 Source distribution Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation an........
  • Execute Local Bash Scripts remotely by SSH


    for ip in `cat fixlist.txt`; do sudo -u apache ssh root@$ip "`cat iptablesrules.sh`" done In the above example we are going to execute the commands within the local file "iptablesrules.sh" on all the machines in "fixlist.txt".  This is a great way of performing server maintenance in a clustered or cloud environment.........
  • MySQL HowTo Copy Duplicate a Table for backup purposes


    This is a great way to test and experiment without risking your current table, or to make a backup of your current table to avoid corruption or dataloss due to malicious activity eg. deletion etc.. There are two steps and two commands 1.) Copy Table Structure "cars_backup" is the new table and it will be a copy of the table called "cars"........
  • Directadmin error/** Found 7 pre-existing rpmdb problem(s), 'yum check' output follows: e2fsprogs-devel-1.41.12-3.el6.i686 has missing requires of e2fsprogs-libs = ('0', '1.41.12', '3.el6') e2fsprogs-devel-1.41.12-3.el6.i686 has missing requires of l


    Solution To The Following: yum -y install zlib-devel yum -y install e2fsprogs* *** Cannot find /usr/include/et/com_err.h.  (yum install libcom_err-devel) *** Installation didn't pass, halting install. Once requirements are met, run the following to continue the install:   cd /usr/local/directadmin/scripts   ./install.sh Common pre-install commands:  http://help.directadmin.com/it........
  • Bad Hard Drive Slows Down Computer


    Here's a proven example of what a bad hard drive can do, it was technically functioning OK in a RAID array but the system became extremely low and the load become high and IOWAIT was even higher and I always thought it was a bad application.  The truth is that this failing 1TB Hitachi has slowly gotten worse and caused huge slowdowns, (eg. 100% load on Thunderbird waiting for e-mails to load etc..).  After swapping it out, tabs change instantly, emails are not lagged, and........
  • How to mount/access a single partition from dd image with Linux


     parted sdc.img GNU Parted 1.8.8 Using /home/one/sdc.img Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) unit                                                  &nb........
  • Linux/Centos how to block SSH bruteforce/dictionary attacks automatically with denyhosts


    A lot of people become nervous (and understandably so) when checking their auth or security logs, in Centos /var/log/secure and see dozens, hundreds of even thousands of attempted logins to various services, especially SSH. Of course you could manually block these people/IPs but no one has time to read the logs like that, what if some program or script could do it for you? This is what denyhosts does for you, it checks the logs and based on a certain number of failed SSH attem........
  • 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........
  • How to recover from dead DRBD partition/hard drive in two simple commands


    This assumes that you've at least created the correct partition for your DRBD already. Notice that I am "diskless", that's because either your DRBD partition doesn't exist/has been renamed (eg. sdb becomes sda when sdb dies and you reboot) or because that drive is really actually dead/gone. *If you need to permanently change the partition/device for your resource be sure to edit /etc/drbd.conf on both hosts and reload the config. (replace r0 with........
  • 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........
  • 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........
  • WD EARS/Green 2TB Cannot Disable Power Saving/Head Parking with hdparm


    hdparm -B 255 /dev/sdb /dev/sdb:  setting Advanced Power Management level to disabled  HDIO_DRIVE_CMD failed: Input/output error   The one thing you can do though is to set hdparm spindown time lower (it doesn't seem to work that well).  -S   set standby (spindown) timeout   hdparm -S 251 /dev/sda /dev/sda:  setti........
  • Ubuntu 10.04/GRUB2 mdadm won't boot


    Moving to RAID was a pain. What you have to do is the following from an existing install: Install mdadm Create your mdadm RAID 1 array on your spare hard drive. Start it with the missing disk. rsync the entire contents of your current / to the md partition. Here's a good way of doing it: rsync -Pha --exclude=/proc/* --exclude=/sys/* --exclude=/mnt/* /. /mnt/md2........
  • VirtualBox Error Failed to start the virtual machine Centos 5.5 Mirror. Medium '/home/testuser/.VirtualBox/HardDisks/Centos 5.5 Mirror.vdi' is not accessible. UUID {a1a9fad7-0402-4867-b8f3-39fb49454bc5} of the medium '/home/testuser/.VirtualBox/HardD


    Virtualbox Error I tried to copy a .vdi of one container to use in another one, basically to clone instead of having to install the OS again. Failed to start the virtual machine Centos 5.5 Mirror. Medium '/home/testuser/.VirtualBox/HardDisks/Centos 5.5 Mirror.vdi' is not accessible. UUID {a1a9fad7-0402-4867-b8f3-39fb49454bc5} of the medium '/home/testuser/.VirtualBox/HardDisks/Centos 5.5 Mirror.vdi' does not match the value {4945a0e8-0ed5-4736-9088-bcaf........
  • FUSE/Curlftpfs mount ftp account as drive partition in Linux


    This is a great way to use your ftp server space, for example on your web hosting account (although I believe many hosts don't allow storage like this), but if you have a VPS/Dedicated Server etc.., this would be perfect.  Imagine how easy it is to work with an ftp account that you can just mount as a normal partition or directory in Linux, it would be great for backups etc..   Name curlftpfs - mount a ftp host as a local directory Synopsis........
  • MySQL Recover/Reset Lost/Forgotten root Password


    One note is to secure MySQL, I don't know for sure but I believe you could login to MySQL remotely with no password during this operation (I'm not sure, maybe it doesn't accept blank passwords but I firewall MySQL port anyway and recommend you do the same). First edit /etc/my.cf Under the [mysqld] field add the following line somewhere: skip-grant-tables Now restart mysql: service mysql restart or on Debian sty........
  • Seagate Drive 500GB Drive Dying


    This drive is clearly on the way out, the Kernel knows it but I'm surprised that SMART is not concerned.  I didn't blame Seagate for their past issues until now.  This hard drive has hardly been used and has not even been powered on for a year according to SMART. Home page is http://smartmontools.sourceforge.net/ === START OF INFORMATION SECTION === Model Family:     Seagate Barracuda 7200.11 Device........
  • Debian/Ubuntu/Kubuntu Bash/Console/Terminal/Putty Home and End Keys Don't Work or Produce a ~


    This is a very weird, annoying and bizarre quirk with many distributions, especially Debian.  The home and end keys don't work, but it's a simple fix as long as you found this article :) You just have to edit /etc/inputrc: Find the commented lines as shown below: # "e[1~": beginning-of-line # "e[4~": end-of-line *If you can't find the above, just copy and paste the code below into your inputrc, it will en........
  • Adventures in pre-paid SIM Cards and data GPRS/Edge/3G in China with China Mobile in Shenzhen, Guangzhou, Shanghai, Beijing and other cities


    This really is a difficult and confusing process for non-Mandarin speakers, but here's what I've done and learned so far: You can purchase an "M-Zone" China Mobile pre-paid SIM Card from almost anywhere but I tried to purchase mine from Suning (a large electronics dealer) hoping they would be able to help me or answer my questions but my plan didn't work out at all.  At Suning once I found someone who spoke some English they gave me the 55 RMB M-Zone China Mobile P........
  • 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).........
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