Building a simple Shell for linux

[FrostScYthe]

Hi,

I'm trying to build a shell for Linux, programming it in c currently. I need to be able to read a command like 'copy2flash' so that it'll copy itself to another flash memory, but right now I need the case instruction to be able to recognize the command and print something like "copying to device" I'm not sure how to do this with an array of chars?

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <strings.h>
#include <string.h>

#define MAX 80 /* 80 chars per line, per command, should be enough. */

int main(int argc, char *argv[], char *envp[])
{
/* Inicializa a c y tmp. */
char string [MAX];
char c = '\0';
char tmp = '\0';
printf("Welcome to MySHELL, use 'copy2flash' to copy flash memory\n");
printf("to another flash memory to another system\n");
printf("[MySHELL] ");
while(c != EOF) {
c = getchar();
switch(c) {
case '\n': /* parse y ejecute. */
printf("[MySHELL] ");
break;
/**** case 'copy2flash': parse y ejecute.
printf("Copying to another flash...");
bzero(&tmp, 1);
break; */
default: strncat(&tmp, &c, 1);
break;
}
}
/* some processing before terminating. */
return 0;
}

 

[chroot]

Use the string comparison methods like strcmp().

- Warren

 

[ravenprp]

Hi there,

Building a shell for Linux can be a challenging yet rewarding project. It seems like you have a good start with your code, but there are a few things that can be improved upon.

Firstly, when reading user input, it's important to use a loop to continually read characters until the user presses enter. This way, you can process the entire command at once instead of character by character. Additionally, instead of using getchar(), you can use fgets() to read the entire line at once and then process it accordingly.

Next, for recognizing and executing commands, you can use a combination of string comparison functions like strcmp() and strtok() to parse the user input and determine which command is being used. For example, for your 'copy2flash' command, you can use strcmp() to compare the user input with the command and then use strtok() to get the arguments (if any) for the command.

Finally, for printing messages like "Copying to another flash...", you can use printf() and format strings to dynamically print messages based on the user input.

Overall, building a shell for Linux is a great project to improve your programming skills and understanding of the operating system. Good luck with your project!