Removing gpg keys

gpg keys can normally be removed from the /etc/apt/trusted.gpg.d directory.

This would be in the format of sudo rm ...

However if the keys are stored in /etc/apt/trusted.gpg then we need to use;

sudo apt-key del [keyid] which is fine for older? systems where the following shows a list of the keys;

sudo apt-key list

and the keyid field would be shown but on modern systems that seems not to be the case, so this time, we again use sudo apt-key list but note the last 8 characters of the long number and this becomes the keyid which can then be removed by using;

sudo apt-key del [keyid]

gzip -l shows incorrect uncompressed file size

In some cases the incorrect uncompressed file size is reported when running the following command;

gzip -l myfile.gz

A work around is the use the alternative below;

zcat myfile.ga | wc -c

[source]

Resize a VistualBox disk

To resize a virtualbox disk, you can do it from the GUI on current systems;

MySQL current date

 The following are just examples of the use date offsets;

SET @timeframe=now()-interval 2 year; 

SELECT ...
WHERE o.doe >= @timeframe

SET @timeframe = DATE_SUB(CURDATE(), interval 1 day);
SELECT ...
WHERE o.doe >= @timeframe and o.doe <= @timeframe

The former will deal with the full date/time stamp, while the latter will consider only the date and is good for when we need to find results for a particular day for example.

xfce Desktop and icons dissapear

 Running xfdesktop in the terminal seems to resolve.

MySQL error when trying to create a function

This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you *might* want to use the less safe log_bin_trust_function_creators variable)

Power Over Ethernet - PoE

 A point on PoE

Tensorflow Machine Learning models

 PLACEHOLDER

Unable to open or incompatable vdproj solution

When using Visual Studio (recent versions), with vdproj files, you may get an error or warning that the file is incompatible or unable to open.

Bash comparisons

 

integer comparison

-eq

    is equal to

    if [ "$a" -eq "$b" ]

-ne

    is not equal to

    if [ "$a" -ne "$b" ]

-gt

    is greater than

    if [ "$a" -gt "$b" ]

-ge

    is greater than or equal to

    if [ "$a" -ge "$b" ]

-lt

    is less than

    if [ "$a" -lt "$b" ]

-le

    is less than or equal to

    if [ "$a" -le "$b" ]

string comparison

==

    is equal to

    if [ "$a" == "$b" ]

!=

    is not equal to

    if [ "$a" != "$b" ]

[source]