Operating System Project (7th semester Oct 2016 - Jan 2017)
version 1.0 last update: 20/1/2017
Aristotle University of Thessaloniki Electrical and Computer Engineering Science
My_Shell - Operating System Project 2016-2017 is an effort to implement a shell or a command line interpreter. This shell is made to work in interactive and in batch mode both and it is up to the user to choose between these two modes. The programming language is C.
Containing files in OS_project.rar:
Makefile for compiling the code, os_project.h (/include), main.c (/src), execute.c (/src), helpers.c (/src), batchfile.bat (/bin)
os_project.h: It is a header that contains all the functions used in this program except main().
main.c: int main(int argc, char *argv[]); ** In this function, the program differentiates the two modes (interactive, batc) and then the appopriate functions are called.
- interactive mode: the user enters the commands from keyboard
( Ability to enter more than one at a time using ';' to separate them )
- batch mode: the user writes the commands in a batch file and then enters this file to
be executed.
execute.c: It includes the main functions to run the commands entered.
void myShell_func(char *commandLine);
** This function creates a double pointer in which the multiple (if there are more)
commands will be stored. Firstly, the parsing takes place and then the execute function
is called for running the commands.
void execute_func(char **commands, int numCom);
** This function creates as many children as needed to execute each command
separately. Every child has to execute a command. Every time, each child parses the
command at " " and checks if there is a quit command entered. If so, the child process
communicates with the parent process through a pipeline. Otherwise the execvp() is called.
helpers.c: This code file contains some helpful functions for the commands' execution.
int parse_func(char *commandLine, char **commands, const char *delim);
** This function returns the number of parses of the string named commandLine, by the delim
connst character.For every delim char in the string, the strtok function parses the string
into tokens and every token is stored in a different place in the commands table.
char *strstrip(char *s);
** This function "clean" the string s from the white-space character that might exist in the
beginning or the end of it.
int checkCommand_func (char *args);
** This function is created in order to check if the given command is a quit or an exit
command.
In order to compile and run this project, a Linux terminal is needed. Follow the steps below to run the My_Shell project.
Step 1: extract all the directories and files in a directory on your PC Step 2: open a Linux terminal Step 3: enter the 'cd' command and type the directory's path where you extracted the files Step 4: enter the command 'make' to the command line **In that step the object files( main.o, execute.o, helpers.o ) will be created automatically in the build directory and the executable file ( My_Shell.exe ) in the bin directory Step 5: enter 'cd bin' to the command line Step 6: type ./My_Shell.exe to run the program in interactive mode OR ./My_Shell.exe batchfile.bat to run the program in batch mode
Academic ID: 8209 Contact info: [email protected]