SetDirectory["C:\\drorbn\\AcademicPensieve\\Classes\\17-1350-AKT"]

Make

Make::usage = "Make[targets, sources, Hold[action]] makes a target, or a list of targets, given sources, or a list of sources, in the style of the unix 'make' command.";
Make[target_String, sources_, action_Hold] := Make[Evaluate@{target}, sources, action];
Make[targets_, source_String, action__Hold] := Make[targets, Evaluate@{source}, action];
Make[targets_List, sources_List, action_Hold] := Module[{},
If[
(And @@ ((FileType[#] =!= None)& /@ sources)) &&
Or[
Or @@ ((FileType[#]===None)& /@ targets),
Min[AbsoluteTime[FileDate[#]]& /@ targets] < Max[AbsoluteTime[FileDate[#]]& /@ sources]
],
Print["Making ",targets, " ..."];
ReleaseHold[action]
]
];

Making

Make[{"About.png", "About_800.jpg"}, "About.pdf", Hold[
DeleteFile[FileNames["temp-*.png"]];
Read["!convert -scene 1 -density 300 -background white -alpha remove About.pdf[0-3] temp.png"];
Read["!montage -geometry +0+0 -frame 0 -background white -tile 2x2 temp-*.png About.png"];
Read["!convert -geometry 800x800 -gamma 0.75 About.png About_800.jpg"];
DeleteFile[FileNames["temp-*.png"]];
MakeThumb["About.png"]; MakeThumb["About_800.jpg"];
]]

Export

{
"TitleNotes" -> "This is my personal notebook for my 2017 <a href=http://drorbn.net/index.php?title=AKT-17>MAT 1350 Algebraic Knot Theory</a> class. <span style=\"color: red;\">Use at your own risk.</span><p>",
"CleanTeX" -> True
}