Ubuntu

Php upgraded to 7.1 while Ubuntu 17.10 upgrading process

If you need to upgrade a Ubuntu with LAMP from 17.04 to 17.10, you need more time due to php upgrading.

Php 7.1 will be installed to replace 7.0. Lots of mods, as well as fpm, need to be reconfigured.

(:з」∠)

Fix Ubuntu Server bash for internet accessing (DNS querying)

I have multiple devices installed with Ubuntu Server. Some of them have a strange problem:
They can access internet using some applications, such as squid, without any problem.
They can ping to internet IP address.
They can use host / dig to query IP by domain name.
They cannot ping to internet by using domain name directly.
They cannot download file through wget / curl using domain name, but can do with IP.
They cannot use apt, stuck at connecting.
All they use a local dnsmasq as their dns.

After a long time dig, I found the problem and here is the fix.
open the file /etc/nsswitch.conf, search the line with “hosts:” and change the setting to “files dns” (without quotes).

Install ubuntu server into Soekris net6501 by using USB boot

This will guide you to prepare a installation media from Windows and install ubuntu into Soekris net6501.

Stuffs you need:

  • a USB stick that CAN BE RECOGNIZED by net6501 device.
    Not sure? Attach it to net6501 and reboot. If you can read the SIZE of this stick while booting, it is.
  • an ISO file for ubuntu server 32-bit. Version 16.10 is tested.
  • rufus. Guide and download point at https://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows.
  • a working serial connection from your workstation to your net6501, software included.

Prepare installation media:

  • Use rufus to build the USB stick. Check the guide above.

Install:

  1. Link net6501 to your computer using serial connection and start the link. In this case, I’m using the default setting (Speed=19200, Data bits=8, Stop bits=1, Parity=None, Flow control=XON/XOFF).
  2. Boot your net6501 with USB stick attached.
  3. Hit ctrl-p to go into bios.
  4. Type “boot 81” (without quotes) and press enter to boot from USB.
  5. You will see that something wrong with gfxboot.
  6. Type this text below SLOWLY and press enter. DO NOT COPY AND PASTE:
    install console=ttyS0,19200
  7. Do not press any key related to screen mode selection. It will be passed.
  8. Choose a language and continue installation steps as normal.

Finalize:

Grub configuration need to be adjusted for using serial as console.

Edit /etc/default/grub and change to these lines below:
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_CMDLINE_LINUX="console=ttyS0,19200 noplymouth"

Then run update-grub.

 

Hope this help you.

Show the System Information again in Ubuntu Server

Every time when I log on my ubuntu server, there always be a System Information displayed. How can we tell to the bash to re-display this screen again?

The command is: landscape-sysinfo

Simply, you just need to type land and press tab key to let the auto complete do the job.

 

Source: http://askubuntu.com/questions/7949/where-does-the-system-information-information-come-from-on-login

use chattr to lock file

chattr

This command can be used to lock a file.

usage: chattr +i filename

The files locked by chattr cannot be modified or deleted, even with root permission.

For unlocking, use chattr -i filename.