Batch reduce resolution of images in Ubuntu Linux

Posted on February 22, 2009

Open a terminal window or shell (who needs a GUI!?)
sudo apt-get install imagemagick
cd image_folder
mkdir resized
for f in *jpg
do
convert -resize 30% $f resized/$f
done

Easier than Photoshop, I reckon!

I needed this today for some photos I was uploading. Photos from recent cameras are huge and Australian bandwidth doesn’t cut it. So this really helps.

Obviously you only need to do the first line once. I found this in the Ubuntu forums but it took me a while to find the right combination of keywords in Google. View the original thread.

I needed to change jpg to JPG, because the camera used uppercase and Linux is case-sensitive. 30% was good for me but you may need to change that.

If you don’t understand this, ask me, I’m happy to help!

Unix Time in MySQL and bash

Posted on February 4, 2009

A quick one today. I was working on a mysql database that used unix timestamp produced by PHP’s time() function.

I needed to be able to quickly convert this time to a human-readable format. In bash,

date -d @timestamp

is a quick way to convert.

In a terminal shell eg:

# date -d @1224992980
Sun Oct 26 14:49:40 EST 2008

In a MySQL client, you could also use

select date(from_unixtime(column_name)) from table_name;

Or if you want a little more flexibility in the output, for example outputting 27/02/09, you could do:

select date_format(from_unixtime(column_name), ‘%d/%m/%y’) from table_name;

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