Linux Mint – Slow Boot Up

Problem

I noticed that my machine would take abit of time to boot. On bootup I pressed ESC to see what was happening, and noticed one of my partitions would take a couple of seconds to be scanned and would then throw a Connection Refused message.

I initially thought that my hard disk what dying but turns out there was a non existent volume in my /etc/fstab file that was trying to be loaded.

Solution

When I checked the systemd-journal logs, I saw the error below:

disk device has failed
disk device has failed

When I searced, I got a clue from this post that this was due to a mis-configured /etc/fstab.

The above swap volume with the UUID starting with “5f1d11af” was trying to be mounted but it doesn’t exist.

check /etc/fstab if volumes listed are correct
The pointer shows the incorrect volume

Confirm the correct existing volumes, using blkid:

check correct volumes using blkid
check correct volumes

Open the /etc/fstab file and comment out this volume (the one on the last line) as shown:

Comment out the wrong volume in /etc/fstab
Comment out the wrong volume in /etc/fstab

After commenting the above, then restart your machine.

References

dev-disk-by\x2duuid.device/start timed out.

GRUB2: Timed out waiting for device (was anciently a swap partition)

Manage Log Messages Under Systemd Using Journalctl

Copy Multiple lines from a logfile

Problem

I needed to capture an error / stack trace (list of the method calls that the application was in the middle of when an Exception was thrown – explanation from stackoverflow) from a log file to another file for attaching to a bug tracker

Solution

Used this answer from unix.stackexchange that proposed using a shell function that used sed that you could enter the from,to line numbers, log file and output file as shown

In the user’s .bashrc file add:

$ tail .bashrc 
#Printing section of a Line From A logFile
printLine () 
{ 
 sed -n -e "$1p" "$2"
}

Useage:

$ printLine 2000,2250 /var/log/tomcat/catalina.out > java_error.txt

Sources

Easy way to copy lines from one file to another

What is a stack trace, and how can I use it to debug my application errors?

Merge Video and Audio into One File

Problem

I downloaded a presentation where the video file and audio files were separate and I needed to merge the video and audio into one file.

Solution

Used the solution posted on super user on this link:

Merging video and audio, with audio re-encoding:

@whiscardz ~ $ ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a aac -strict experimental output.mp4

Copying the audio without re-encoding:

@whiscardz ~ $ ffmpeg -i video.mp4 -i audio.wav -c copy output.mkv

Sources

How to merge audio and video file in ffmpeg