What does $* mean in a make command? - gnu-make

There's a command in a batch file that I didn't write that reads:
make -f foo_mk $*
Printing * using the echo command gives me a list of the files in that folder i.e foo1_mk and foo1.mk. Calling the command does not appear to give the same output as though I called:
make -f foo1_mk $foo1_mk
make -f foo1_mk $foo1.mk
So what does $* mean in this context?

For GNU Makefiles
The body of a rule in a makefile has access to special variables, including $* which expands to the stem with which the pattern of the rule matches.
You can find a list of these automatic variables in the GNU Make Manual

Related

Defining local variable in Makefile target

How to define local variable in Makefile target?
I would like to avoid repeating filename like:
zsh:
FILENAME := "text.txt"
#echo "Copying ${FILENAME}...";
scp "${FILENAME}" "user#host:/home/user/${FILENAME}"
But I am getting an error:
FILENAME := "text.txt"
/bin/sh: FILENAME: command not found
Same with $(FILENAME)
Trying
zsh:
export FILENAME="text.txt"
#echo "Copying ${FILENAME} to $(EC2)";
Gives me an empty value:
Copying ...
You can't define a make variable inside a recipe. Recipes are run in the shell and must use shell syntax.
If you want to define a make variable, define it outside of a recipe, like this:
FILENAME := text.txt
zsh:
#echo "Copying ${FILENAME}...";
scp "${FILENAME}" "user#host:/home/user/${FILENAME}"
Note, it's virtually never correct to add quotes around a value when assigning it to a make variable. Make doesn't care about quotes (in variable values or expansion) and doesn't treat them specially in any way.
The rules for a target are executed by the shell, so you can set a variable using shell syntax:
zsh:
#FILENAME="text.txt"; \
echo "Copying $${FILENAME}..."; \
scp "$${FILENAME}" "user#host:/home/user/$${FILENAME}"
Notice that:
I'm escaping end-of-line using \ so that everything executes in
the same shell
I'm escaping the $ in shell variables by writing $$ (otherwise
make will attempt to interpret them as make variables).
For this rule, which apparently depends on a file named text.txt,
you could alternatively declare text.txt as an explicit dependency and then write:
zsh: text.txt
#echo "Copying $<..."; \
scp "$<" "user#host:/home/user/$<"

How to make a single makefile that applies the same command to sub-directories?

For clarity, I am running this on windows with GnuWin32 make.
I have a set of directories with markdown files in at several different levels - theoretically they could be in the branch nodes, but I think currently they are only in the leaf nodes. I have a set of pandoc/LaTeX commands to run to turn the markdown files into PDFs - and obviously only want to recreate the PDFs if the markdown file has been updated, so a makefile seems appropriate.
What I would like is a single makefile in the root, which iterates over any and all sub-directories (to any depth) and applies the make rule I'll specify for running pandoc.
From what I've been able to find, recursive makefiles require you to have a makefile in each sub-directory (which seems like an administrative overhead that I would like to avoid) and/or require you to list out all the sub-directories at the start of the makefile (again, would prefer to avoid this).
Theoretical folder structure:
root
|-make
|-Folder AB
| |-File1.md
| \-File2.md
|-Folder C
| \-File3.md
\-Folder D
|-Folder E
| \-File4.md
|-Folder F
\-File5.md
How do I write a makefile to deal with this situation?
Here is a small set of Makefile rules that hopefuly would get you going
%.pdf : %.md
pandoc -o $# --pdf-engine=xelatex $^
PDF_FILES=FolderA/File1.pdf FolderA/File2.pdf \
FolderC/File3.pdf FolderD/FolderE/File4.pdf FolderD/FolderF/File5.pdf
all: ${PDF_FILES}
Let me explain what is going on here. First we have a pattern rule that tells make how to convert a Markdown file to a PDF file. The --pdf-engine=xelatex option is here just for the purpose of illustration.
Then we need to tell Make which files to consider. We put the names together in a single variable PDF_FILES. This value for this variable can be build via a separate scripts that scans all subdirectories for .md files.
Note that one has to be extra careful if filenames or directory names contain spaces.
Then we ask Make to check if any of the PDF_FILES should be updated.
If you have other targets in your makefile, make sure that all is the first non-pattern target, or call make as make all
Updating the Makefile
If shell functions works for you and basic utilities such as sed and find are available, you could make your makefile dynamic with a single line.
%.pdf : %.md
pandoc -o $# --pdf-engine=xelatex $^
PDF_FILES:=$(shell find -name "*.md" | xargs echo | sed 's/\.md/\.pdf/g' )
all: ${PDF_FILES}
MadScientist suggested just that in the comments
Otherwise you could implement a script using the tools available on your operating system and add an additional target update: that would compute the list of files and replace the line starting with PDF_FILES with an updated list of files.
Final version of the code that worked for Windows, based on #DmitiChubarov and #MadScientist's suggestions is as follows:
%.pdf: %.md
pandoc $^ -o $#
PDF_FILES:=$(shell dir /s /b *.md | sed "s/\.md/\.pdf/g")
all: ${PDF_FILES}

Can I use the .SHELLFLAGS variable to choose "bashrc" file in GNU-Make?

Is it possible to tell the SHELL, e.g. bash, to use a specific (bash)rc file using .SHELLFLAGS?
Below you will see two examples. The first shows what I want to do, and the second illustrates one way of achieving the desired result.
The reason for me asking is that I have a bashrc file (from OpenFOAM) defining a bunch of variables and functions that I want to use in various recipes.
Thank you for your time.
example (not working)
file: bashrc:
export HELLOWORLD="Hello World"
file: Makefile:
SHELL=/bin/bash
.SHELLFLAGS=--rcfile bashrc --
test:
#\
echo "$${HELLOWORLD}"
example (working)
file: bashrc:
export HELLOWORLD="Hello World"
file: Makefile:
.ONESHELL:
SHELL=/bin/bash
test: ; source bashrc
#\
echo "$${HELLOWORLD}"
If you read the bash man page related to the --rcfile option you'll find:
--rcfile file
Execute commands from file instead of the system wide initial‐
ization file /etc/bash.bashrc and the standard personal initial‐
ization file ~/.bashrc if the shell is interactive (see INVOCA‐
TION below).
Note particularly that the shell must be interactive for this to have any effect, but a shell that make invokes is of course not interactive.
Second, if you read the GNU make manual on .SHELLFLAGS you'll see that the default value is -c (or -ec in POSIX mode); the -c option allows the shell to read the script to run from the command line, which is how make invokes the shell. This means when you replace .SHELLFLAGS with your own value, you have to include that.
So with your makefile when make runs the shell it will use this command line:
/bin/bash --rcfile bashrc -- 'echo "${HELLOWORLD}"'
which is clearly not going to work. You need to set .SHELLFLAGS like this:
.SHELLFLAGS = --rcfile bashrc -ic --
The -i option forces an interactive shell, and you need the -c option to tell make to run the first non-option argument as a command.

terminal command to act on filenames that don't contain text

I have a directory full of files with names such as:
file_name_is_001
file_name_001
file_name_is_002
file_name_002
file_name_is_003
file_name_003
I want to copy only the files that don't contain 'is'. I'm not sure how to do this. I have tried to search for it, but can't seem to google the right phrase to find the results.
Details depend on operating system, shell, etc.
For a unix system a quite verbose but easy to understand approach could look like this (please mind that I didn't test it):
mkdir some_temporary_directory
mv *_is_* some_temporary_directory
cp * where_ever_you_want_to_copy_it
mv some_temporary_directory/* .
rmdir some_temporary_directory
You can do this using bash. First, here's a command to get you a list of files that don't contain the text _is_:
ls | grep -v "_is_"
This takes the output of ls and matches all values with DO NOT contain _is_ using grep -v.
In order to then copy these files, we need to turn the lines output by grep into arguments of cp. We can do this using xargs:
ls | grep -v "_is_" | xargs -J % cp % new_folder
From the xargs man page, it is a tool to "build and execute command lines from standard input".

Run a command multiple times with arguments given from standard input

I remember seeing a unix command that would take lines from standard input and execute another command multiple times, with each line of input as the arguments. For the life of me I can't remember what the command was, but the syntax was something like this:
ls | multirun -r% rm %
In this case rm % was the command to run multiple times, and -r% was an option than means replace % with the input line (I don't remember what the real option was either, I'm just using -r as an example). The complete command would remove all files in the current by passing the name of each file in turn to rm (assuming, of course, that there are no directories in the current directory). What is the real name of multirun?
The command is called 'xargs' :-) and you can run it as following
ls | xargs echo I would love to rm -f the files

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