Simple Shell in Unix

用C練習了一個簡單的shell，在這做一下重點筆記。

#include                                      
...
                                                                    
#define MAXLINE 80 
...                                  

void handle_SIGINT();
...

int hindex;
...            

void handle_SIGINT(){
        int i = hindex - 1;
        char tmp[MAXLINE]; 
        write(STDOUT_FILENO, "\nHistroy:\n", 10);
        for(;i > (hindex - 10) && i >= 0;i--){   
                ...
        }                                              

        signal(SIGINT, handle_SIGINT);
        write(STDOUT_FILENO, "\n COMMAND->", 11);
}                                                

void processBuffer(char inputBuffer[], char* args[], int length, int* background){
        /* 處理inputBuffer，把他變成一個一個arg儲存在args中 */
}                                                                                            

void readHistory(char* args[], char fletter, int* background){
        int i;                                                
        for(i = hindex - 1; i >= (hindex-10); i--)            
                if(*history[i] == fletter) break;             
        strcpy(history[hindex - 1], history[i]);              
        processBuffer(history[i], args, strlen(history[i]), background);
}                                                                       


void setup(char inputBuffer[], char* args[], int* background){
        /* 讀入user input並且呼叫processBuffer負責處理，順便紀錄在history中 */
}

int main(void){
        char inputBuffer[MAXLINE];
        int background; /* indicate if the program run in background when '&' at the end */
        char* args[MAXLINE/2 + 1];

        hindex = 0; /* initilize the history index which point to the next history storage */


        while(1){
                background = 0;
                printf(" COMMAND->");
                fflush(stdout);
                signal(SIGINT, handle_SIGINT); /* set up, when program received the control + c
                                                  it will invoke the handle_SIGINT function */
                setup(inputBuffer, args, &background);
                if(!fork()){
                        execvp(args[0], args);
                }else{
                        if(!background)
                                wait();
                }
        }
}

signal(SIGINT, handle_SIGINT);

是收到signal時，會呼叫哪個function來處理。

原始檔案連結:Link