• chroot in Linux Howto Simple and Easy Guide


    chroot which stands for change root allows you to virtually operate in another operating system even though you haven't booted it. It is commonly used to deploy new distros, applications and to fix a broken Linux/Unix install or prep a new system image without having to physically boot the drive or disk. So in this example let's say we have a drive that has a Linux OS installed on /dev/sdb1 and we have mounted this partition on /mnt/sdb1 The key point is to edit the &quo........
  • Debian / Mint / Ubuntu net-tools packages provides netstat, ifconfig, route, arp and other classic network admin tools


    The net-tools command brings back all of the oldschool tools that we're used to: /bin/netstat /sbin/ifconfig /sbin/ipmaddr /sbin/iptunnel /sbin/mii-tool /sbin/nameif /sbin/plipconfig /sbin/rarp........
  • Linux How To Rename Files


    To remove all spaces from all files in the current directory linux rename remove spaces rename "s/ //g" * how to replace part of the text with another (it is almost like using sed): rename s/"Screenshot at 2019-04-22 "/"AC97-Windows-InstallSolution"/g * The first part "Screenshot at 2019-04-22" is what we're looking for The........
  • 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........
  • Centos 5 OpenSSL does not support TLS 1.2 Apache Error


    [Thu Jan 26 14:13:31 2017] [notice] caught SIGTERM, shutting down [Thu Jan 26 14:14:00 2017] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Thu Jan 26 14:14:00 2017] [error] Server certificate is expired: 'Server-Cert' [Thu Jan 26 14:14:00 2017] [notice] SSL FIPS mode disabled [Thu Jan 26 14:14:07 2017] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Thu Jan 26 14:14:07 2017] [error] Server certificate is expired: 'Server-Ce........
  • 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........
  • tsclient (Terminal Server RDP Client) missing in Debian, Ubuntu, Linux Mint


    This was a horrible shock after upgrading fromUbuntu 9 to Linux Mint 17 and I found that the last distro to support tsclient was Debian Squeeze. For some reason it has disappeared for a long time and the new options such as rdesktop and gnome-rdp do not have any start menu entry and just aren't done as well as tsclient. Fortunately there is a solution: tsclient surprisingly can be downloaded as a direct .deb package and it fails with some variou........
  • 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........
  • mdadm enable bitmap to speed up rebuilds


    Have you ever unplugged the wrong drive and then had to rebuild the entire array? It may not be a big deal in some ways but it does make your system vulnerable until the rebuild is done. Many distros often enable the "bitmap" feature and this basically keeps track of what parts need to be resynced in the case of a temporary removal of a drive from the array, this way it only needs to sync what has changed. To enable bitmap to speed up rebuilds and sync........
  • Centos 6 RTL8111/8168B r8169 link up and down error solution/fix


    02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) For whatever reason it seems the r8169 driver that ships and has shipped with most Linux distros for years is still flawed and does not work properly on these cards, causing 100mbit connectivity when it should be 1gbit and even worse, causing random network dropouts. The r8169 driver in Linux kernels is simply not meant to be used on th........
  • 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........
  • vi problem in Ubuntu/Debian distros when editing up,down,left,right arrow keys produce A,B,D,C respectively


    This is very annoying, the only known fix is to install vim apt-get install vim After that everything works as normal.........
  • 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........
  • Convert doc images/jpg/jpeg to PDF


    Use "ImageMagick" which can be installed easily on most UNIX/Linux distros. Remember that it will go with the standard file listing to determine the order but I believe you can manually specify multiple jpg's in the arguments. Convert image/jpg to PDF convert *.jpg yourpdf.pdf This is a very handy and free tool. Convert DOC/TXT documents to PDF If you wanted to convert a .doc file or text........
  • 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........
  • EOL for Kubuntu/Ubuntu 8.04 - W: Failed to fetch http://ca.archive.ubuntu.com/ubuntu/dists/intrepid/universe/source/Sources.gz 404 Not Found [IP: 91.189.92.171 80]


    I couldn't figure out whyI couldn't install a simple package. This is what's annoying about cutting edge Debian distros, yes we know you support each license on average for 1-2 years but why take down the supporting binary packages and basically disable the older versions? sudo apt-get install update Reading package lists... Done Building dependency tree Reading state information... Done E: Couldn't find p........
  • LUKS/cryptsetup Tutorial for Linux Hard Drive Partition Encryption


    This is based on Debian Linux but should apply equally to any *nix distro. Install LUKS/crypt-setup apt-get install cryptsetup Setup your LUKS Partition Of course change /dev/md2 with whatever partition you intend to use LUKS on. cryptsetup --verbose --verify-passphrase luksFormat /dev/md2 You'll be asked to verify your decryption password twice *DO NOT FORGET THIS PASSWORD AS IT IS NOT RECOVERABLE!........
  • 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........
  • How To Set DHCP/Static IP Address in Centos/RHEL/Fedora & Debian/Ubuntu/Kubuntu/MEPIS Set DHCP/Static IP Address


    Basically the two main types of distros are Debian and RHEL/Centos based. I'm just going to give a quick overview of how the configuration of IP interfaces works in Debian/Centos based distros. *Just one thing to remember, when setting IPs statically you have to manually specify a DNS server in /etc/resolv.conf (since DHCP is what normally does it automatically) Debian/Ubuntu/Kubuntu/MEPIS The IP (DHCP &........
  • Debian 5.04 RAID 1 mdadm boot problem GRUB error


    I successfully created a single RAID 1 partition which includes /boot inside it and my root directory through the Debian installer. It said GRUB installed successfully but when I try booting the OS it seems GRUB can't read anything. When trying to boot from GRUB GRUB Loading stage 1.5. GRUB loading, please wait... Error 2 I get "Error 2" when trying to boot Debian. I also notice from a LiveCD that........
  • XMPP Chat Protocol using Jabber - Guide Tutorial Setup Linux Chat Server


    In Debian based distros: apt-get install jabber Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: fakeroot dkms Use 'apt-get autoremove' to remove them. The following extra packages will be installed: jabber-common The following NEW packag........
  • OpenVZ backup container to a single file while it's running using "vzdump"


    Proxmox has made this free utility to backup running OpenVZ containers. It's a great program which is actually just a PERL script but gets the job done. This program is not 100% required because all it really does is cp -a from your container's path as far as I know but it is still good to have uniformity to how you backup your containers. For RPM distros such as Centos/RHEL/Fedora etc.. download and install this: wget http://www.proxmox.com/cms_proxm........
  • FreeBSD Desktop OSs


    FreeBSD Desktop OSsI would probably choose these over Linux. In many ways these are probably more stable and just as easy to use as any Linux distros but the benefit of stable, updated and secure packages! PC-BSD - http://www.pcbsd.org DesktopBSD - http://www.desktopbsd.net/index.php?id=37 Personally PC-BSD is Beta at this point and is not easy if you are installing it on a non-primary partition. I have not used Deskt........
  • 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 IOoperation or in plain English, there is a delay in........
  • 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........
  • Timezone Change/Updated for Linux/Unix Debian/Fedora/Ubuntu/Centos Change Update Time zone


    This way should work on all Linux machines, at least RHEL/Debian (Ubuntu) based distros but most likely all and also should work on many Unix style machines I believe. Many OS's have tools to update the timezone, but most of them (even if command line) require several bloated packages and even Xorg/KDE based packages etc.. Your time zone info file is actually in /etc/localtime if you open this file in vi/vim/pico you'll see it's gibberish (binary code or another encodin........
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