Ubuntu Troubleshooting

Error: Too many open files in system

Unable to get a directory listing or execute some commands. Console returns error message containing the text "Too many open files in system."

Everything in Linux are files; Linux forks most things including devices, sockets and pipes as files. There is a kernel parameter called “file-max” which controls the maximum number of files that can be opened in a system. The default value is 65K (approx), can be find using the following command:

sysctl -a | grep file-max

To check the count of number of files open, we can use the following command:

lsof | wc -l

To prevent Ubuntu from running out of filehandles you need to make sure that there are enough file handles available at the system level, and that the user you are running Ubuntu as is allowed to use enough file handles:

Run the command sysctl -a. If this is less than 200000, increase the number of file handles by editing /etc/sysctl.conf and changing the property fs.file-max to 200000. If there isn't a value set already for this property, you need to add the line fs.file-max=200000.

vi /etc/sysctl.conf

add to file:

fs.file-max=200000

save and execute the command:

sysctl -p

Ubuntu changes computer clock on reboot

On a dual boot system, or comparing bios time to the time in Ubuntu- Windows tries to keep HW clock at the local time. Linux tries to keep them at the UTC.

sudo vi /etc/default/rcS

Set

UTC=no

After this configured properly, you should again enable automatic sync in both Linux and Windows.

note: does not work in Linux Mint 18 (works in Ubuntu)

As a second thing to try,

sudo timedatectl set-local-rtc 1

To check out if your system uses Local time execute the command:

timedatectl

Slow Graphics Performance

One known issue is that fglrx is no longer supported with Ubuntu 16.04, as AMD is working on a new open-source driver. Apparently, the default NVidia driver is "nouveau" and it doesn't support 3D acceleration.

You can run sudo ubuntu-drivers devices to see the detected drivers.

sudo ubuntu-drivers devices

In the list it offered a "recommended" driver. For example, nvidia-304 - distro non-free recommended

sudo apt install nvidia-304

ref: https://askubuntu.com/questions/761429/kubuntu-16-04-driver-manager-broken

If you would like to test and see if 3D Acceleration is supported or enabled then use the following:

/usr/lib/nux/unity_support_test -p

Another helpful testing utility is in mesa-utils and is called glxgears

sudo apt install mesa-utils
glxgears

Install Nvidia driver instead of nouveau: ref: https://askubuntu.com/questions/481414/install-nvidia-driver-instead-of-nouveau

note: drivers not compatible with 16.04. Only working resolution thus far is to downgrade.

See also: Video Driver and OpenGL Troubleshooting in Linux

Graphic Driver Problems in Ubuntu

For cards made by manufacturers such as Nvidia the drivers are often not open source. With each new release of the OS, video drivers may become outdated and no longer work. For example, many users are reporting problems with the Nvidia drivers in Ubuntu 16.04. Troubleshooting can involve a number of steps. Resolution may also require you to use an older version of the Linux distribution until the manufacturer releases current or updated drivers.

Example driver location for Nvidia cards on Ubuntu: Linux x64 (AMD64/EM64T) Display Driver

system error popup

A crash report does not go away, even if you choose to submit the report to Ubuntu development. You will continue to be notified about the same crash that occurred in the past, even if the problem has been resolved. To delete the crash reports do:

sudo rm -f /var/crash/*

Now you will not see a crash report unless another crash occurs. If the same software program or process is still faulty and continues to crash when executed, then new crash reports will be generated. If you do not wish to be notified of future crashes by a crash report you can disable the Apport system crash report facility.

sudo vi /etc/default/apport

Change "enabled=1" to "enabled=0"