UNIX for Dummies Questions & Answers

Code:

file1.h : file2.h file3.h

file1.exe : file4.c file5.c
     gcc -o file1.exe file4.c file5.c

file4.c file5.c : file1.h

I was looking up how to make a Makefile and i came across this can someone just explain what it is or does?

Thanks.

first line:
file1.h: file2.h file3.h

means.... that file1.h needs action if older than file2.h or file3.h.
however, no action specified.

file1.exe : file4.c file5.c
gcc -o file1.exe file4.c file5.c

means.... that file1.exe depends on the source files: file4.c and file5.c and
file1.exe will be compiled if file4.c or file5.c are newer than file1.exe

file4.c file5.c : file1.h

means file4.c and file5.c are dependent on file1.h -- but there is no action specified.


In this example, I believe that file1.exe will be recompiled if file4.h, file5.h, file1.h, file4.c or file5.c are newer than file1.exe

I would've done this file like so:

Code:

file1.exe: file1.h file2.h file3.h file4. file5.c
        gcc -o file1.exe file4.c file5.c

would do the same and is more straightforward.

ALSO. In the case where no action is specified, make tries to use default rules.
These rules can be examined by typing:

make -p

HTH

Thanks alot.