• dovecot: imap(root@localhost)<3702>: Error: Mailbox INBOX: mmap(size=352609044) failed with file /var/spool/mail/root/Maildir/dovecot.index.cache: Cannot allocate memory


    If you get this error you may assume it is a lack of memory, which it could be, but more likely it is the default memory size of 256M. The file in this example was about 350M big which of course exceeds the virtual memory limits. This makes sense in smaller mail servers but if you have large amounts of users or e-mails this limit should be bumped. Check your default size limit: doveconf -n | grep -E 'vsz_limit|service imap' default_vsz_limi........
  • Linux dhcp dhclient Mint Redhat Ubuntu Debian How To Use Local Domain DNS Server Instead of ISPs


    If you are running a local DNS server like named/bind and don't want to use the ISPsupplied DNS servers that are announced via a DHCP request (using dhclient) then the solution is simple. The reason should be obvious, but normally running your own DNS server will provide a more reliable, and fast DNS response and you won't have to worry about filtering as much (unless your upstream filters or proxies outgoing DNS requests). Edit /etc/dhcp/dhclient.conf........
  • Linux grub not using UUID for the root device instead it uses /dev/sda1 or other device name solution


    You can read lots of posts about this issue but there is not much information about why this is the case or how grub determines the root= device name. Some even suggest modifying grub.cfg manually which is a disaster as the next kernel update will cause grub to revert back to the device name. For most people this won't be an issue but those using template system, automated deployments and working in embedded may run into this issue with custom embedded and created minimal kernel........
  • /var/log/journal huge/too large solution in Debian Mint Ubuntu Linux Howot Fix


    Is your /var/log/journal overweight and bloated? For example a decent install of Debian 11 with most applications and services ends up being about 4.9G with the journal taking a few gigs. du -hs /var/log/journal/ 1.3G /var/log/journal/ By default in a lot of distributions there is no maximum size so it will keep growing. This is especially problematic for embedded distributions and devices, but is also a huge waste of sp........
  • CentOS 8 how to convert to a bootable mdadm RAID software array


    The cool thing here is that we only need 1 drive to make a RAID 10 or RAID 1 array, we just tell the Linux mdadm utility that the other drive is "missing" and we can then add our original drive to the array after booting into our new RAID array. Step#1 Install tools we need yum -y install mdadm rsync Step #2 Create your partitions on the drive that will be our RAID array Here I assume it is /dev........
  • strange vi errors in Linux Mint/Ubuntu line 58: E488: Trailing characters: t_Sbet line 63: E171: Missing :endif


    This happens on any file an even just typing "vi"whereas it never happened before. I suspect an update or environment variable is causing this issue When entering vi I get this weird stuff line 58: E488: Trailing characters: t_Sbet line 63: E171: Missing :endif When exiting vi I get this weird stuff t_Sb=^[[4%?%p1%{1}%=%t........
  • Ubuntu Linux Slow/Delayed SSH ping response Solution


    I've only ever seen this in Ubuntu for some reason and it is because of the /etc/nsswitch.conf settings. So the issue is that if the hostname's reverse DNS cannot be found that you need to go back to DNS which was not the default in this nsswitch.conf file for some strange reason. Edit /etc/nsswitch.conf and replace your "hosts" line with this: #hosts: files dns mdns4_minimal [NOTFOUND=return] mdns........
  • kvm cannot boot xen guest using lvm


    This booting error is because the Xen PV guest image uses the Xen kernel, this is not compatible with anything but a host running a Xen kernel. I did a kpartx -av virtual.img and then it created some partitions that showed up in fdisk. I mounted it and did a chroot into it and removed the xen kernel and installed a normal kernel but Xen still shows the same kernel in Grub (only the Xen one). This is strange but it seems like this Xen PV guest has some sort of hidden or........
  • pcnet32: eth0: transmit timed out, status 97fb, resetting - NIC card problem solution


    I've encountered this problem before and I believe it may affect other drivers (I could test but I don't have time). This was happening on my custom Linux system with the pcnet32 driver. pcnet32: eth0: transmit timed out, status 97fb, resetting (and some other kernel module tracing in dmesg) Basically it means the card is connected (it shows connected in full duplex etc.. and recognized if the cable is disconnected too) but no packets can be sent or received........
  • Heredoc warnings


    Heredoc warningsExample $somevariable = ........
  • 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........
  • Latest Articles

  • How to combine .txt ACLs without breaking things
  • How to ping all of Googlebot's IPs script
  • 'virtio0' uses a qcow2 feature which is not supported by this qemu version: QCOW version 3
  • Linux bash script to get the IP of a list of hostnames
  • How To Use Camera Webcam in Docker for OBS Studio etc...
  • Computer Server Won't Post Boot Or Enter BIOS Setup After Installing RAID SAS or GPU Card etc..
  • How To Test PHP Scripts from CLI with GET variables/query string
  • apt-cache how to see all available versions of a package in Debian Ubuntu Mint
  • Virtualbox VBox Guest-utils drag and drop files stops working with Windows VMs
  • How To Remove Ubuntu Netplan and Go Back to /etc/network/interfaces
  • How To Force Flash an AMD Instinct GPU To Another Model Using Debian Ubuntu Mint Linux
  • How To compile ollama from source to use unsupported AMD GPU with rocm in Ubuntu Debian
  • QEMU KVM Virtio GPU Windows Cannot Select 1080P
  • Linux Gnome Desktop Ubuntu Mint Debian Gets Slower After Weeks
  • Firefox How to Save Full Page As Screenshot/PDF
  • Nvidia Datacenter Driver Tesla Slow nvidia-smi response and high utilization with 0 usage
  • ffmpeg how to normalize / increase the volume of your audio
  • kdenlive audio blips pops cracks artifacts solution fix
  • haproxy / nginx certbot SSL issues
  • nginx how to see the real IP when behind a CDN