Checking file size in makefile, stopping if file is too short

Question

Is there a way to check if the size of a particular file is less than some constant? I'm assuming things about size in the makefile and want to make sure I'll get an error if my assumptions are not met. Something like assert, but in makefile.

if filesize(file) > C then error
else continue compilation

Answer 1

Put this in your rule, somewhere before the compilation:

 test -n "$$(find filename -a -size +NNNc)"

where filename is the filename and NNN is the size in octets. This returns false and halts make when the size is less than or equal to NNN.

Answer 2

My approach for this, is probably not the most pretty solution, but it worked for me :)

CHECKFILE = \
    if [ ! -f "file" ]; then \
        echo "file does not exist" ; exit 1 ; \
    fi; \
    FSIZE=$$(du -b "file" | cut -f 1) ; \
    if [ $$FSIZE -lt 100000 ]; then \
        echo "filesize too small" ; exit 1 ; \
    fi

all:
    @$(CHECKFILE)

Answer 3

I prefer this-- continue if greater than 256 bytes, otherwise stop make-- for readability:

test `wc -c <$<` -gt 256;

Within the backticks, the file $< is directed into wc -c, which returns the size in bytes of $<. After the backticks evaluate the size of $<, test is then used with the -gt "greater than" operator.