Clarifying target names to avoid doubling tasks. Self-documentation in Makefile. Extensive documentation in README
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*Tools for working with scanned pages*
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# Tools for scanned pages
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Makefile:
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Get help on the different makefile targets by running:
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* `make dirs`: create the working folder structure
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`make`
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* `make tessaract` **dependency: tesseract**
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* `make myscript`
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# Makefile Documentation
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* `make visualization`: **dependency: mplayer** creates visualization of images/ dir, by cating the images content into mplayer. See more option ins [shiftop](https://git.bleu255.com/shiftop/file/shiftop.html)
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* `make wordtagger`: **dependency: tesseract** Uses scanned pages as an input, tags each word for their wordtype (noun, verb etc) and saves it in a text file.
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## SYNTAX: AUTOMATIC VARIABLES
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* `make talktochatbot`: **dependency: ChatterBot** talkes with the ocred file
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https://www.gnu.org/software/make/manual/html_node/Automatic-Variables.html
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* $@ file name of the target of the rule.
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* $< name of the first prerequisite.
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* $? names of all the prerequisites that are newer than the target, with spaces between .
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* $^ names of all the prerequisites,
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* $(@D) directory part of the file name of the target,
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## SYNTAX: PRINTING / ERRORS
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@ preceeding command tells make not to print the command being executed
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- preceeding a command tells make to ignore errors in a recipe line
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## DEPENDECIES AND RULES
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a rule "asks" a *dependency* to be executed, only if the depency does not exist as a file
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i.e. I have the 2 following rules in my make file:
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```
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list.txt:
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ls . -1 > $@
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tts: list.txt
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cat $< | espeak
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```
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when i run: `make tts`
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tts rule will execute its dependency list.txt IF the list.xt does not exist in the top level of working directory. ELSE it will execute the list.txt
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## TARGET NAMES
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**use as rules' targets (first line of a rule,left of :) the name of resulting file(s)**
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One main problem in the OuNuPo makefile is the execution of the tesseract rule, every time another rule requests it (in make lingo has it as a dependency). This a duplication of the same process (ocr), which takes quite some time, and hence we want to avoid repeting, if the scanned images haven't changed.
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Make has a very simple way of **avoiding this duplication of a process/rule**.
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It is done **carefully defining the rules' target** - the name given to the rule, by which we invoke in order to execute that rule.
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By having **the target of a rule take the name of the file(s), which will result from to the rule's execution**, the Makefile, will **check if that file is "out of date"**.
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"A target is out of date if it does not exist or if it is older than any of the prerequisites "
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If the target/resulting file(s) are **not present**, the dependency rule will be executed
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If the target/resulting file(s) are **not present**, the dependency rule will NOT be executed
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what follows is a simple example
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```
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foo.txt:
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echo "this is a test" >> foo.txt
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@echo "$@ was made"
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art: foo.txt
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cat foo.txt | figlet
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@echo "$@ was made"
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```
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For the first time you run `make art` the foo.txt dependency rule will be executed
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In subsequent runs of `make art` foo.txt dependency rule will NOT be executed, because its target: foo.txt is already in the make working directory
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To trigger the execution of foo.txt ruke, we need to remove its target from the working directoy
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That task if often delegate to a rule with target `clean` which removes the files/targets of make, such as
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```
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clean: removes output (target) files
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rm ocr/output.txt
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rm $(wildcard output/*)
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rm $(tmpfile)
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```
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After running `make clean` the foo.txt rule is executed (as a dependancy) when running `make art`
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Tagets can also include subfolders:
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```
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output/art.txt: foo.txt
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cat foo.txt | figlet > $@
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@echo "$@ was made"
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```
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which can be invoked by `make output/art.txt`
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Read more on https://www.gnu.org/software/make/manual/html_node/Rule-Syntax.html#Rule-Syntax
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# LINKS
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* About Makefile syntax: [5 Writing Recipes in Rules](https://www.gnu.org/software/make/manual/make.html#Recipes)
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