/ - 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 Permissions and Groups Real Usecase for Group Access


    I have a directory structure which the primary user needs full access on but wanted a user to access only a specific directory within the main directory (so they could write in there only and nowhere else). Here's what I did: [root@compevo8001 dllnow]# ls -alh drwxrwxr-x  2 someuser software  4.0K Oct 19  2017 ExpireYMD-2017-11-20 drwxrwxr-x  2 someuser software  4.0K Nov 19  2017 ExpireYMD-20........
  • vi error solution E166: Can't open linked file for writing


    This is not so much of a vi error as it is a physical filesystem error in the sense that the file you are trying to write to is a symlink and the destination doesn't exist or for some other reason is inacessible. So vi is tellng you "you're writing to a symlinked file and the file the symlink points to cannot be written to".  This is especially highlighted byt he fact that if you are using wq! to write and you still get the error.........
  • Apache htaccess Custom ErrorDocument not working properly for root home page 403 Error Issue and Solution


    So I have a domain "testdomain.com". Inside test domain.com's root is the following .htaccess: Options +FollowSymLinks -Indexes ErrorDocument 403 /launch/index.html Order Deny,Allow Deny From All Allow From 192.168.1.2 When you visit anything other than root things work fine.  Eg. if you visit http://testdomain.com/somedirfile.html It will show the right error in /launch/........
  • 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........
  • 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.........
  • ecryptfs errors


    ecryptfs-mount-private Enter your login passphrase: Inserted auth tok with sig [ee16d84] "into the user session keyring mount: No such file or directory" [  156.118113] ecryptfs_mount: kern_path() failed [  156.118431] Reading sb failed; rc = [-2] [  164.233055] traps: mate-notificati[3472] trap int3 ip:7f43d7002c13 sp:7fff162c6600 error:0 [  166.017061] ecryptfs_mount: kern_path() failed........
  • Linux SAMBA does not work with symlinks


    At first I thought it's just not possible but there is actually an option that can be enabled to make symlinks work with Samba. Then I put this under the [global] section Note: It's "wide links" and not "wide symlinks" (some other sites have incorrect info which was a frustrating waste of time :))   Add this to your smb.conf follow symlinks = yes wide links = yes unix ex........
  • grubby fatal error: unable to find a suitable template solution Centos


    vzkernel-2.6.32-042stab116.2.x86_64.rpm                                                                           &n........
  • There was a problem importing one of the Python modules required to run yum. The error leading to this problem was:


    There was a problem importing one of the Python modules required to run yum. The error leading to this problem was:    No module named yum Please install a package which provides this module, or verify that the module is installed correctly. It's possible that the above module doesn't match the current version of Python, which is: 2.7.9 (default, Apr 21 2016, 16:51:58) [GCC 4.4.7 20120313........
  • cp copy all contents of directory to another one including hidden files and folders howto


    cp -a /your/source/. /your/dest/ -a preserves all file atributes and symlinks the "." at the end of /source/ includes all hidden files such as .htacess, .bash_history, .ssh etc.. The / in /dest/ makes sure the contents go into it instead of replacing /dest itself (eg. if you did not have the / at the end).........
  • Apache Vhost HowTo Serve Same Content using a different domain and IP


    There are a few ways of doing this and all basically involve using the reverse proxy or "ProxyPass" feature of Apache to accomplish it. 1.) Create a normal vhost and simply symlink the root directory of the site you want to mirror. Eg. originalsite.com and newsite.com /vhosts/originalsite.com/httpdocs You would symlink like this: ln -s /vhosts/originalsite.com/httpdocs vhosts/originalsite.com/........
  • Vbox/Virtualbox devices grayed out for non-root user solution


    <p>It is a permissions issue that is hard to fix.</p> <p><strong>All but one USB device is greyed out.</strong></p> <p>I am already a member of &quot;vboxusers&quot;</p> <ul> <li>I have already enabled and disabled USB support for the guest.</li> <li>I have already reinstalled the latest VBOx guest editions</li> <li>If running as root it all works fine</li> <li>Changing........
  • cp ignore symlink and copy the actual file


    This can be very tricky, say you are doing development on a file that is symlinked.  Doing a "cp dev.file dev.file-bk" won't do what you expect, it just links back to the same file so you haven't copied or backed anything up. You need the "-H" switch to copy the actual file that is referenced by the symlink: cp -H dev.file dev.file-bk........
  • Linux copy file and not just the symlink, How-To/Solution


    cp -L index.php index.php-2013-08-21 The -L switch is what you need because it's a huge issue if you think you've copied a file for backup purposes but it really just creates a symlink to the original file.........
  • mkdir(): Too Many Links - The Solution and Problem in ext3 filesystems


    The error itself "mkdir(): Too Many Links" is not very useful, but I'll translate it into plain English. It means you've reached the filesystem's limit of how many directories can be created in a single directory. In this case for ext3 the limit is 32000 and it was exceeded. What's the solution?  The simple solution is to move those directories into more subdirectories possibly sorting them by date, alphabet or numerically. ........
  • 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........
  • rsync my favorite/best/optimal default switches and options


    Not sure what rsync switches/options to use? rsync -PDrphogtl The short version would be: rsync -Pha I think these are really common sense options to use and probaby should be the default. Explanation of rsync switches P = display the progress D = hybrid of --specials and --devices so all special and device files will be copied as well. r = recursive (otherwise rsync won't copy files deeper than........
  • Linux Kernel Compilation (Intel(R) 82575/82576 PCI-Express Gigabit Ethernet support ) Error - drivers/net/igb/igb_main.c: In function `igb_up': make[3]: *** [drivers/net/igb/igb_main.o] Error 1


    Linux Kernel v2.6.30.3 102220 blocks   CHK     include/linux/version.h   CHK     include/linux/utsrelease.h   SYMLINK include/asm -> include/asm-x86   CALL    scripts/checksyscalls.sh   CHK     include/linux/compile.h   CC      drivers/net/igb/igb_main.o drivers/net/igb/igb_main.c: In function `igb_up':........
  • Process/Parse PHP from HTML files using .htaccess and allowoverride


    RemoveHandler .html .htmAddType application/x-httpd-php .php .htm .html Just add the above into the .htaccess file for your website. Also remember that you need to be allowed to override the Apache and this should go into the vhost for your site as shown below: # you need the AllowOverride otherwise .htaccess directives will be ignored<Directory "/www/vhosts/complaintdb.com/httpdocs">Options FollowSymLinksAllowO........
  • iPhone Enable Tethering Manually Update ipcc Carrier Settings/Update via SSH


    Everyone says there is a "manual" way of doing it and then they tell you to use iTunes, but if you're like me, you're travelling on business in a foreign country and your laptop does not have iTunes and you don't have a way of getting it and/or don't want it. For this example I'm using the provider "du" in Dubai, UAE (United Arab Emirates) but this method works for virtually all providers.  The requirements in this case to truly "manually update........
  • 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........
  • Apache Ignoring/Not processing .htaccess file


    I was getting very frustrated one day wondering why it appeared my .htaccess file was being ignored and not processed by Apache.  No matter what I did it was obvious that Apache didn't care about my .htaccess file.  Then I realized that the default settings must be in effect, which is that my vhost didn't explicitly allow me to override the default settings. This usually comes down to your vhost settings. Make sure you have an entry like this in your Apache vhost settings in........
  • OCFS2 crash


    When trying to even cd or ls the mounted OCFS2 partition it crashes.  I think this is a combination of VMWare Server's problem and the way I mounted and symlinked to it. More than anything this shows the problem and lack of forsight with VMWare, but also that OCFS2 is easily crashed if you do strange things. Output of /var/log/messages for OCFS2   Apr 10 15:57:45 localhost kernel: [84331.691258] Modules linked in: vmnet vmci vmmon ocfs2_stac........
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