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Here weвЂ™re using the -i (ignore case) option so that the case of matching strings is disregarded. Pipe the output from dmesg through grep to search for particular strings or patterns. The last ten messages are retrieved and listed in the terminal window. Of course, you can retrieve any number of messages. Use the tail command to retrieve the last tenВ kernel ring buffer messages. To exit from the real-time feed, hit Ctrl+C. When new messages appear they are displayed by dmesgВ at the bottom of the terminal window.Д®ven mounting a CD-ROM disk is seen as a change, because youвЂ™ve grafted the contents of the CD-ROM disk onto the directory tree. Note that you are not returned to the command prompt.

Fire up a virtual machine, and youвЂ™ll see new information arriving in the ring buffer. Even virtual hardware will cause new messages to appear in the ring buffer.

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If you plug in a USB drive or connect or disconnect a Bluetooth device, youвЂ™ll see messages in the dmesg output.

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Update or add a kernel module, and youвЂ™ll see ring buffer messages about those changes. If the ring buffer is used to store messages from events that take place during the startup sequence, how can live messages arrive in the ring buffer once the computer is up and running?ДЄnything that causes a change in the hardware connected to your computer will cause messages to be sent to the kernel ring buffer.

To see messages as they arrive in the kernel ring buffer, use the -followВ (wait for messages) option.В That sentence might seem a little strange. This option doesnвЂ™t automatically invoke less. If all youвЂ™re bothered about is the sequence of events, this is good enough.В Also, note that youвЂ™re dumped back at the command prompt. The timestamps are rendered as standard dates and times, but the resolution is lowered to a minute.Д®verything that happened within a single minute has the same timestamp. H is the вЂњhumanвЂќ option, -T is the вЂњhuman readableвЂќ option.) sudo dmesg -T If you donвЂ™t require nanosecond accuracy, but you do want timestamps that are easier to read than the defaults, use the -T (human readable) option. TheВ messages that occurred in each minute are labeled with the seconds and nanoseconds from the start of that minute. The timestamps show a timestamp with the date and time, with a minute resolution.The output is automatically displayed in less.To have this rendered in a more human-friendly format, use the -H (human) option. To force dmesg to always default to a colorized display use this command: sudo dmesg -color=alwaysД«y default, dmesg use a timestamp notation of seconds and nanoseconds since the kernel started. If it isnвЂ™t, you can tell dmesg to colorize its output using the -L (color) option. sudo sysctl -w kernel.dmesg_restrict=0Д«y default, dmesg will probably be configured to produce colored output. But, be aware: it lets anyone with a user account your computer use dmesg without having to use sudo. If you want to avoid having to use sudo each time you use dmesg, you can use this command.

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RELATED: How to Use the less Command on Linux Removing the Need for sudo Start the search function by pressing the forward slash key вЂњ/вЂќ in less.

You can use the search function within less to locate and highlight items and terms youвЂ™re interested in. Now we can scroll through the messages looking for items of interest.

Obviously, what we need to do is pipe it through less: sudo dmesg | less sudo dmesgДЄll of the messages in the ring buffer are displayed in the terminal window. By default, you need to use sudo to use dmesg. The dmesg command allows you to review the messages that are stored in the ring buffer. Because it contains these low-level startup messages, the ring buffer is a good place to start an investigation into hardware errors or other startup issues.Д«ut donвЂ™t go empty-handed. The kernel ring buffer stores information such as the initialization messages of device drivers, messages from hardware, and messages from kernel modules. Conceptually it can be thought of as a вЂњ circular buffer.вЂќ When it is full, newer messages overwrite the oldest messages. It is simple in design, and of a fixed size. To avoid losing notable error messages and warnings from this phase of initialization, the kernel contains a ring buffer that it uses as a message store.ДЄ ring buffer is a memory space reserved for messages. In the very early stages of initialization, logging daemons such as syslogdВ or rsyslogd are not yet up and running. The startup processes then pick up the baton and complete the initialization of the operating system. The boot processes ( BIOS or UEFI, MBR, and GRUB) take the initialization of the system to the point where the kernel is loaded into memory and connected to the initial ramdisk ( initrd or initramfs), and systemd is started. In Linux and Unix-like computers, booting and startup are two distinct phases of the sequence of events that take place when the computer is powered on.