Diff 2 remote files:
diff <(ssh <user>@<server1> 'cat /path/to/file1') <(ssh <user>@<server2> 'cat /path/to/file2')

If using it in a script you'll need to add a $ like so:
diff <$(ssh <user>@<server1> 'cat /path/to/file1') <$(ssh <user>@<server2> 'cat /path/to/file2')

Video capture your desktop.
ffmpeg -f x11grab -r 25 -s hd1080 -sameq -i :0.0 out.mpg

Convert epoch time in CSV file
for f in `cat | awk -F',' '{print $2}'`; do sed -i "s/"$f"/$(date --date "$f seconds 1 January 1970" +%d-%m-%Y)/" ;done