When umount says target is busy, but no process can be blamed

A short one: What to do if unmount is impossible with a # umount /path/to/mount umount: /path/to/mount: target is busy but grepping the output of lsof for the said path yields nothing. In other words, the mount is busy, but no process can be blamed for accessing it (even as a home directory). If this [...]

systemd: Reacting to USB NIC hotplugging (post-up scripting)

The problem Using Linux Mint 19, I have a network device that needs DHCP address allocation connected to a USB network dongle. When I plug it in, the device appears, but the DHCP daemon ignored eth2 (the assigned network device name) and didn’t respond to its DHCP discovery packets. But restarting the DHCP server well [...]

Linux: Command-line utilities for obtaining information

There are many ways to ask a Linux machine how it’s doing. I’ve collected a few of them, mostly for my own reference. I guess I’ll add more items as I run across new ones. General Info inxi -Fxxxz (neat output, but makes the system send me security “password required” alert mails because of attempts [...]

systemd / DBus debugging starter pack

Introduction Trying to solve a 90 second wait-on-some-start-job on each boot situation, I found that there’s little info on how to tackle a problem like this out there. Most web pages usually go “I did this, hurray it worked!”, but where do you start solving a problem like this if none of the do-this-do-that advice [...]

Solved: systemd boot waits 90 seconds on net-devices-eth0

Introduction After installing wireshark (and tons of packages it depends on) on a rather fresh and bare-boned Debian 8 (Jessie), I got the “A start job is running for sys-subsystem-net-devices-eth0.device” message for a minute and half on every boot. It was exceptionally difficult to find the reason, because so many packages were installed along with [...]

Replacing ntpd with systemd-timesyncd (Mint 18.1)

Introduction It all began when I noted that my media center Linux machine (Linux Mint 18.1, Serena) finished a TV recording a bit earlier than expected. Logging in and typing “date” I was quite surprised to find out that the time was off by half a minute. The first question that comes to mind is [...]

Upgrading to Linux Mint 19, running the old system in a chroot

Background Archaeological findings have revealed that prehistoric humans buried their forefathers under the floor of their huts. Fast forward to 2018, yours truly decided to continue running the (ancient) Fedora 12 as a chroot when migrating to Linux Mint 19. That’s an eight years difference. While a lot of Linux users are happy to just [...]

Linux + APC Smart UPS 750 notes (apcupsd and other stuff)

Introduction These are my somewhat messy jots while setting up an APC Smart UPS 750 (SMT750I) with a Linux Mint 19 machine, for a clean shutdown on power failure. Failures and mistakes shown as well. Even though I had issues with receiving a broken UPS at first, and waiting two months for a replacement (ridiculous [...]

Lubuntu 16.04 on ARM: Turning off the “Suspend” etc. options

In short On an embedded ARM-based Lubuntu 16.04, I had LXDE’s logoff dialog window offering suspend as an option, and when that was chosen, the system got itself into some nasty state with network and keyboard off. The serial console was still active, and yet, I was better off without it. It turned out that [...]

systemd random jots

As systemd seems to be here to stay (or at least I hope so), this is a post of random notes to self that I jot down as I explore it. It will probably grow with time, and become a mixture of basic issues and rather advanced stuff. Useful references man systemd.service and man systemd.unit [...]