This is the synopsis of the first Linux programming lab.

The description of the problem to be solved

During the whole course one problem should be solved: restore a password from a hash code generated by htpasswd command. The password should be restored using several approaches:

• recursive brute force,
• iterative brute force,
• multi threaded brute force on a machine with several CPUs,
• distributed over the network brute force.

The roadmap of the course

• Hello world application.
• Recursive brute force solution.
• Iterative brute force solution.
• Multi-threaded brute force solution.
• Synchronous thread per client solution.
• Asynchronous thread per client solution.
• Reactor implementation.

Topics covered in the first lab

• Linux shell commands introduction.
• Source code editor.
• Hello world application.
• Stages of program compilation.
• Primitive Makefile for the hello world application.
• GNU coding standards

Linux shell commands introduction

Bash reference manual

The commands used during the lab are:

• mkdir - create a directory,
• cd - change a directory,
• rm - remove a file,
• ls - list content of a directory,
• gcc - compile source code,
• make - run make utility,
• ./hello_world - run the hello world application.

Source code editor

GNU Emacs manual

Emacs is one of orthodox editors for C programming.

Here is a list of the most often commands for editing in Emacs:

• C-x-f - open file
• C-x-s - save file
• C-x-b - switch buffer
• C-x-u - undo
• C-space - set mark
• A-w - copy
• C-w - cut
• C-y - paste (yank)
• C-e - end of line
• C-a - beginning of line
• C-A-q - indent block
• Esc-Esc-Esc - escape
• C-q - cancel key sequence
• A-x - run command:
  • shell - run bash,
  • compile - run make,
  • grep - run grep,
  • replace-string - replace.

Hello world application

Solution that was implemented by the end of the first lab:

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#include <stdio.h>
#include <stdlib.h>

int
main (int argc, char * argv[])
{
  printf ("Hello world\n");
  return (EXIT_SUCCESS);
}

Stages of program compilation

GCC manuals You can determine the version of your gcc using command:

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gcc --version

Stages of compilation.

• preprocessor - the result is source code file,
• translator - the result is object file,
• linker - the result is executable file.

The command line used to compile the application.

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gcc -g -o hello_world -Wall -Werror -O2 hello_world.c

Make utility

GNU Make manual

The Makefile used to compile the application

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all: hello_world

CFLAGS+= -g -Wall -Werror -O2

GNU coding standards

The GNU coding standards

References

• The C Programming Language. Kernighan, Brian W.; Ritchie, Dennis M.
• The Practice of Programming. Kernighan, Brian W.; Rob P.
• Advanced Programming in the UNIX Environment.
• Richard Stevens; Stephen A. Rago
• The Unix Programming Environment. Kernighan, Brian W.; Rob P.
• The Art of Unix Programming. Eric S. Raymond
• Advanced Linux Programming. Mark Mitchel; Jeffrey Oldham; Alex Samuel
• The Linux Programming Interface: A Linux and UNIX System Programming Handbook. Michael Kerrisk
• The Standard C Library. Plauger P. J.
• UNIX Network Programming, Volume 1: Networking APIs: Sockets and XTI.
• Richard Stevens
• UNIX Network Programming, Volume 2: Interprocess Communications.
• Richard Stevens