SYSTEMS PROGRAMMING LABORATORY I - Getting Started

• Examples:
  • Compile and run the code.
  • Analyze the code and output.
  1. If you don't know the name of the man(1) page you want, you can perform a keyword search. The following shows how you could search for information about changing owners of a file:

     $ man -k owner
     

  2. Another way this can be done on most systems is to use the apropos(1) command:

     $ apropos owner
     

  3. About gcc; try following commands

     $ gcc --version
     $ type cc
     cc is /usr/bin/cc
     $ ls -li /usr/bin/cc
     $ type gcc
     gcc is hashed (/usr/bin/gcc)
     $ ls -li /usr/bin/gcc
     

     Since both /usr/bin/cc and /usr/bin/gcc link to the same i-node 7951 (some number) in the example, you know that these two files are linked to the same executable file.
  4. Compiling with GCC; following programs are given, compile and link. http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/main.cmain.c http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/reciprocal.cppreciprocal.cpp http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/reciprocal.hppreciprocal.hpp
     Steps are;

     $ gcc -c main.c
     $ gcc -E main.c -o main.pp
     

     Examine main.pp.

     $ gcc -x cpp-output -c main.pp -o main.o
     $ g++ -c reciprocal.cpp
     $ g++ -c -D NDEBUG reciprocal.cpp
     $ g++ -c -D NDEBUG=3 reciprocal.cpp
     $ g++ -c reciprocal.cpp
     

     Check the size of reciprocal.o.

     $ g++ -c -O2 reciprocal.cpp
     

     Compare the new size with the previous.

     $ g++ -o reciprocal main.o reciprocal.o
     $ ./reciprocal 7
     The reciprocal of 7 is 0.142857
     

     Link with a library say libncurses.

     $ g++ -o reciprocal main.o reciprocal.o -lncurses
     

     If it is not in your path, locate it by locate command; type

     $locate  libncurses
     

     Then say it is the path; /usr/local/lib/ncurses. Give the location of this library by

     % g++ -o reciprocal main.o reciprocal.o -L/usr/local/lib/ncurses -lncurses
     

     Check the sizes and compare with the cases you compiled without library flags.

     % g++ -o reciprocal reciprocal.o main.o -lncurses -static
     

     Check the sizes and compare with the cases you compiled without static.
  5. Error Checking and Warnings Consider http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/pedant.cpedant.c. Steps are;

     %gcc pedant.c -o pedant
     

     this code compiles without complaint.

     %gcc -ansi pedant.c -o pedant
     

     Again, no complaint.

     %gcc -pedantic pedant.c -o pedant
     pedant.c: In function `main?:
     pedant.c:9: warning: ANSI C does not support `long long?
     

     The code compiles, despite the emitted warning. (These messages may be different.)

     %gcc -pedantic-errors pedant.c -o pedant
     pedant.c: In function `main?:
     pedant.c:9: ANSI C does not support `long long?
     

     With -pedantic- errors, however, it does not compile. GCC stops after emitting the error diagnostic.
• Exercises:
  1. Write

     $man gcc
     

     and read once to see how many possible flags we have.
  2. Compile, link and execute the following codes with the appropriate flags; $-Wall, -ansi, -pedantic, -pedantic-errors, -DSHOW\_PID, ...$
     http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/asgn1.casgn1.c http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/asgn2.casgn2.c http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/asgn3.casgn3.c http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/uargs.cuargs.c http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/uvars.cuvars.c Analyse and compare the outputs for different flags.
  3. Modify the files http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/makefilemakefile and http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/MakefileMakefile so that able to compile the files given above in one makefile with appropriate flags. We do not a specific purpose, just increase your ability to write a makefile.