[make] use input/output files inside makefile

[whired123]

First a few details

$ tree
├── makefile
├── snippet.txt
└── template.txt

$ cat template.txt 
aaa $input bbb

$ cat snippet.txt 
xxx

$ cat makefile 
test:
	sh -c "input=$(cat snippet.txt) envsubst < template.txt > output2.txt"

Let's do some tests

$ input=$(cat snippet.txt) envsubst < template.txt > output1.txt

$ make
sh -c "input= envsubst < template.txt > output2.txt"

Let's look at the outputs

$ cat output1.txt 
aaa xxx bbb

$ cat output2.txt 
aaa  bbb

Why doesn't xxx appear in the output2.txt file?

 

[whired123]

Single quotes instead of parentheses

$ cat makefile 
test:
    sh -c "input=`cat snippet.txt` envsubst < template.txt"


$ make
sh -c "input=`cat snippet.txt` envsubst < template.txt"
aaa xxx bbb

Works!!!