A sudo in Linux allows to execute commands with the security privileges of another user, by default the root user.
This short note shows how to run commands as another user using sudo. (more…)
linux
Reinstall GRUB from Live USB (UEFI + LVM)
There are many reasons why you may need to reinstall GRUB: corrupted boot partition; GRUB got overridden after Windows installation; some unsupported Linux kernel parameters have been set in a GRUB configuration file and the system is not booting anymore but this can’t be fixed from a GRUB menu as it is not showing up, etc.
In this note i am describing a particular case of how to repair GRUB by reinstalling it from a live USB if a broken system is configured to boot in UEFI mode and a system’s disk is partitioned to LVM.
I have tested this GRUB reinstallation on Ubuntu Linux, though all of the commands below should work for the other Linux systems as well. (more…)
Zip Without Compression – Windows, Linux, MacOS
If you want to store a big folder as a single file, so it could be easily uploaded somewhere or shared with someone, you can create a simple zip archive from it.
To avoid wasting a time and resources on compression and decompression, this zip archive can be created without compression.
In this short note i will show how to create a zip file without compression from the command line on Windows, Linux and MacOS. (more…)
Save All the Terminal Output to a File – Linux
In Linux terminal you can save not only an output of the individual commands using different types of redirections, but you can also capture and save to a file all the commands executed during a session and their output.
All the commands executed in a Linux terminal and their output can be saved to a file using a script command.
The script command creates a session during which it saves everything displayed on a terminal to a specified file.
In this short note i am showing how to save all the terminal output to a file in Linux using the script command. (more…)
Mount LVM Partition in Rescue Mode
Usually, for the system repair purposes, such as troubleshooting of the boot-related issues (e.g. GRUB rescue) or for data recovery, it is required to know how to mount an LVM partition in a live Linux session (when a system boots from a live CD/DVD or from a special rescue USB stick).
In this article i will show how to identify volume groups and logical volumes on an “external” drive and how to mount the discovered LVM partitions in a rescue mode and get access to the data. (more…)
Linux Rescue USB – Data Recovery & System Repair
Rescue and recovery disks are used for repairing a system and data after a crash on Linux and Windows devices.
They are especially useful for troubleshooting of the boot-related issues and for data recovery.
In this note i will show how to create a bootable rescue USB stick with a SystemRescue (also known as a SystemRescueCD) – a Linux-based rescue toolkit for administrating and repairing of the Windows and Linux-based systems and data recovery. (more…)
Network Printer is Printing Gibberish – Ubuntu/Linux
If your network printer is printing gibberish and random characters that is a common driver-related issue.
I had this problem on Ubuntu and Linux Mint with my Samsung M2070 printer connected over Wi-Fi network.
When I tried to print some single-page document, the printer went crazy and printed out a series of strange random symbols on multiple sheets. (more…)
Check BIOS Version in Ubuntu Linux – Command
BIOS is a firmware interface between a computer’s hardware and the operating system and like any software, it can be updated.
Knowing the BIOS version can tell you if you have the most up-to-date version of the BIOS or it has to be updated.
This note shows how to check the BIOS version in Ubuntu Linux from the command-line, though these commands should work for the other Linux systems as well. (more…)
‘GRUB_TIMEOUT’ Change – Not Working [SOLVED]
If you have tried to change a timeout in GRUB by setting the GRUB_TIMEOUT but this doesn’t work and you still see the 30 second timeout, this may be related to the GRUB’s “recordfail” feature.
If the recordfail variable is being set to true, i.e. there was a failed boot attempt (or you use LVM/UEFI with which this feature doesn’t work as expected), GRUB will ignore the GRUB_TIMEOUT and will change the timeout to GRUB_RECORDFAIL_TIMEOUT (by default, 30 seconds).
In this short note i will show how to chance the timeout in GRUB if changing the GRUB_TIMEOUT doesn’t work. (more…)
Signing Failed: Agent Refused Operation [SOLVED]
While attempting to connect to some server over SSH, you may get the error as follows:
sign_and_send_pubkey: signing failed for RSA “/home/<username>/.ssh/id_rsa” from agent: agent refused operation
The “agent refused operation” error is usually caused by too open permissions on a private key file.
In this short note i am showing how to fix this error. (more…)