Linux

To temporarily disable syntax highlighting in GNU nano, use the -Ynone option:

Instead of

nano myfile.php

use

nano -Ynone myfile.php

In order to permanently disable nano syntax highlighting, run this command:

echo "alias nano='nano -Ynone'" >> ~/.$(echo $SHELL | rev | cut -d/ -f1 | rev)rc
source ~/.$(echo $SHELL | rev | cut -d/ -f1 | rev)rc # Reload immediately

This will add nano -Ynone as an alias for nano into your .bashrc or .zshrc

To get just the name of the shell, e.g. bash or zsh, use

echo $SHELL | rev | cut -d/ -f1 | rev

Example:

$ echo $SHELL | rev | cut -d/ -f1 | rev
bash

To get the full path of the current shell executable, use

echo $SHELL

Example:

$ echo $SHELL
/bin/zsh

Run

id -g

to get the GID of the current user’s primary group. Example:

$ id -g
1000

You can also get the GID of another user’s primary group:

$ id -g root
0

Run

id -u

to get the current user’s UID. Example:

$ id -u
1000

You can also get another user’s UID:

$ id -u root
0

If you see an error message like this in Wireshark:

this is because your current user doesn’t have permission to capture packets from your network card.

This can be the case even if you have selected to allow normal users to capture packets during the Wireshark installation process. This is because the setting only takes effect after logging out and logging back in (or rebooting).

To fix the issue temporarily without logging out, run Wireshark as root: sudo wireshark

In order to fix the issue permanently, ensure your user is added to the wireshark group:

sudo usermod -a -G wireshark $USER

and then log out and log back in again (or reboot your computer).

On the command line, run

sudo mokutil --sb-state​

This will tell you

SecureBoot enabled​_

if secure boot is currently active on your machine or

SecureBoot disabled

else.

In case you see an error message like

bash: command not found: mkoutil

you need to install mokutil first using

sudo apt install mokutil​_

To install ddrescue, run

sudo apt -y install gddrescue

lsusb lists all the USB devices to your computer.

Example output:

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 8087:0a2b Intel Corp. 
Bus 001 Device 002: ID 04f2:b5e8 Chicony Electronics Co., Ltd 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Each line represents a single USB device – but an USB device might also be internal to the computer and not connected to a physical USB port. For example, Bus 001 Device 003: ID 8087:0a2b Intel Corp. is an internal Bluetooth modem in my notebook.

Explanation:

• Bus 001: The device is connected to the first USB bus (001) on the system
• Device 003: In the aforementioned bus, the device has been assigned the ID 003.
• ID 8087:0a2b: This is the ID assigned to that device. The first part (8087) is the Vendor ID (VID). The second part (0a2b) is the Product ID (PID). These IDs are assigned by the USB Implementer’s forum. This ID will always stay the same for any given device. If you buy a USB product multiple times, all of them will have the same ID.
• Intel Corp.: This is the description of the device. Often Linux can show you more information, but in this case it’s just the name of the manufacturer.

A PPA (Personal Package Archive) is a repository where you can download packages, that is software, for Debian-based Linux distributions like Ubuntu.

In contrast to “normal” package source that are provided and maintained by distribution providers, PPAs can be created by anyone in order to publish one’s software or special versions of third-party software.

PPAs are hosted on Launchpad, a platform made and supported by Canonical, the company behind Ubuntu.

Are PPAs safe?

While in principle one could publish dangerous software on a PPA, in practice there is virtually no risk since:

• Most often the PPA is provided by the original author of the software and can hence be trusted, if the software you want to install is trusted
• PPAs are frequently used by amateurs and experts alike
• You can only upload source DEB packages to the PPA which is built on Canonical’s server. This reduces the likelihood of smuggeling in binaries with malicious software.
• Malicious PPAs are quickly removed once reported

Still it is good practice to keep in mind that installing software from anywhere – including PPAs – has a chance (although a very little one) to compromise your computer.

Problem:

You are trying to run iotop but you see an error message like

Netlink error: Operation not permitted (1)

The Linux kernel interfaces that iotop relies on now require root priviliges
or the NET_ADMIN capability. This change occured because a security issue
(CVE-2011-2494) was found that allows leakage of sensitive data across user
boundaries. If you require the ability to run iotop as a non-root user, please
configure sudo to allow you to run iotop as root.

Please do not file bugs on iotop about this.

Solution:

You need to run iotop as root:

sudo iotop

The reason for this is that iotop needs to access kernel interfaces that are only accessible to root users or if the user/process has the CAP_NET_ADMIN capability. In theory you could add this capability using sudo setcap cap_net_admin+ep /usr/sbin/iotop but on Ubuntu 18.04 this did not work for me.