Makefiles

1. Software Tools Makefiles

2. make Overview • The make utility helps… • Keep track of which modules of a program have been updated • To ensure that when you compile a program you use the latest versions of all program modules.

3. The make Utility • Large programs often have many source and header files that depend on one another. • After you change a file that others files depend on, you must recompile all the dependent files. • For example: • Several source files • 1 header file (used by all source files) • After you change the header file, each source file must be recompiled. • The header file might depend on other header files, etc. num.h tab.h form.h size.c length.c size.o length.o form.exe

4. The make Utility • Determining which modules to recompile can be difficult when working on large programs. • The make utility automates the process. • make looks at dependencies in a file named makefile in the working directory. • Dependencies specify a target file depends on one or more prerequisite files. • If a prerequisite file has been modified more recently than its target file, make updates the target file based on construction commands. • make normally stops if it encounters an error during the construction process.

5. makefile Format • Themakefileformat: target: prerequisite-list [TAB] construction commands • Thetargetis the name of the file that depends on the files in the prerequisite-list. • Theconstruction-commandsare regular commands to the shell that usually compile and/or link the target file. • Themakeutility executes the construction-commandswhen the modification time of one or more of the files in the prerequisite-list is more recent than the target file.

6. make Example 0 form.exe: size.o length.o cc –o form.exe size.o length.o size.o length.o form.exe

7. make Example 1 $ cat makefile form.exe: size.o length.o cc –o form.exe size.o length.o size.o size.c form.h cc –c size.c length.o: length.c form.h cc –c length.c form.h: num.h table.h cat num.h table.h > form.h • The last line shows that you can put any Bourne Shell command on a construction line. num.h tab.h form.h size.c length.c size.o length.o form.exe

8. make Example 2 compute.h $ cat makefile # # makefile for compute # compute.exe: compute.o calc.o cc –o compute.exe compute.o calc.o compute.o compute.c compute.h cc –c compute.c # the calc.o dependency is optional, and is included automatically calc.o: calc.c cc –c calc.c # delete temporary files such as .o files clean: rm *.o compute.c calc.c compute.o calc.o compute.exe

9. make Example 2 $ ls –l total 22 -rw-rw---- 1 horner cs 179 Jan 21 18:20 calc.c -rw-rw---- 1 horner cs 354 Jan 21 16:02 calc.o -rwxrwx--- 1 horner cs 6337 Jan 21 16:04 compute.exe -rw-rw---- 1 horner cs 780 Jan 21 18:20 compute.c -rw-rw---- 1 horner cs 49 Jan 21 16:04 compute.h -rw-rw---- 1 horner cs 880 Jan 21 16:04 compute.o -rw-rw---- 1 horner cs 311 Jan 21 15:56 makefile $ make cc –c compute.c cc –c calc.c cc –o compute.exe compute.o calc.o

10. make Example 2(continued) • The touch utility updates the date of a file to now. $ make ‘compute.exe’ is up to date. $ touch calc.c $ make cc –c calc.c cc –o compute.exe compute.o calc.o $ touch compute.h $ make cc –c compute.c cc –o compute.exe compute.o calc.o $ make clean rm *.o $

11. Disks Usage Statistics • df display free blocks and # of files in each file system $ df / (/dev/dsk/c0t0d0s0 ): 2459020 blocks 313329 files /proc (/proc ): 0 blocks 3870 files /dev/fd (fd ): 0 blocks 0 files /etc/mnttab (mnttab ): 0 blocks 0 files /var (/dev/dsk/c0t0d0s3 ): 3126728 blocks 341949 files /var/run (swap ): 4512192 blocks 26131 files /cache (/dev/dsk/c0t0d0s4 ): 329020 blocks 241130 files /tmp (swap ): 4512192 blocks 26131 files /home (/dev/dsk/c0t0d0s7 ):25771604 blocks 1629180 files /usr/local (/cache/cache/.cfs_mnt_points/cssvr12:_export_ug_sol_local_1117):50357454 blocks 4209362 files /homes/horner (wine:/export/ug_staff/horner): 7852022 blocks 754200 files /share/share (cssvr9:/usr_local_share): 1260818 blocks 774330 files • du display disk usage statistics (in number of 512k blocks) $ du | head -5 282 ./zmodem 14 ./gzip-0.7/msdos 2 ./gzip-0.7/os2 662 ./gzip-0.7 3626 ./mail du shows disk usage of directories in 512k blocks