Linux

Connecting Wacom One CTL-672/KO-CX tablet to Ubuntu Linux

  • by kjohri

Wacom One CTL-672/KO-CX is an 8.5 inch x 5.3 inch graphic tablet which can be connected to a computer via a USB port. The tablet comes with a pressure sensitive cordless pen. Once connected to a computer via a USB port, pen and tablet work like a mouse on a mouse pad, giving a very fine pointer on the screen.… Read more

MCE hardware error cpu 0

  • by kjohri

1.0 Error

While running Ubuntu 18.04.1 on a laptop, the following errors were observed.

mce: hardware error cpu 0 machine check 0 bank 6 ae0000000040110a
mce: hardware error tsc 0 addr ffb07540 misc 238a0000086
mce: hardware error processor 0:40651 time 1540082330 socket 0 Apic 0 microcode 24
ipmi dmi invalid offset 0

The system would stop in the single user mode.… Read more

systemd – System and service manager in Linux

  • by kjohri

1.0 Introduction

systemd is the newer init system used in most Linux distributions since 2015. The first widely used init system was the System V init process, sysvinit. Ubuntu introduced the Upstart init system with Ubuntu 6.10 in 2006. Ubuntu fully migrated to systemd with Ubuntu 15.04 in 2015.… Read more

Syslog

  • by kjohri

1.0 Syslog

Syslog is a protocol for conveying event notification messages.

Syslog was first developed by Eric Allman for logging as a part of the Sendmail project in the 1980s. It soon became a de-facto standard for logging on Unix-like systems.… Read more

D-Bus Tutorial

  • by kjohri

1.0 D-Bus

D-Bus is a mechanism for interprocess communication under Linux and other Unix-like systems. D-Bus has a layered architecture. At the lowest level is the D-Bus wire protocol described in the D-Bus Specification. The libdbus library is an implementation of the wire protocol.… Read more

Dovecot: imap Error: open (/var/mail/username) failed

  • by kjohri

While configuring mail on a Ubuntu Linux server running the Postfix mail server and Dovecot IMAP server, the following errors were observed in the mail log files,

dovecot: imap(user1): Error: open(/var/mail/user1) failed: Permission denied (euid=1002(user1) egid=1002(user1) missing +w perm: /var/mail, we're not in group 8(mail), dir owned by 0:8 mode=0775)
dovecot: imap(user1): Error: Failed to autocreate mailbox INBOX: Internal error occurred.
Read more

tmpfs in Linux

  • by kjohri

1.0 tmpfs

tmpfs is a filesystem that resides in the main memory of a Linux system. In the case of disk files, a file is first fetched into the kernel pagecache and the delivered to the requesting process. The fetch part is not there in the case of tmpfs as the files are created and updated directly in kernel caches.… Read more