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.

2006-02-27