shell简单实现

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <signal.h> #define MAX_LINE 80 #define BUFFER_SIZE 50 char buffer[BUFFER_SIZE]; char *history[10][10]; int nextPosition=0; int CommandLenth[10]={0}; void ProcessRCommand(char *args[]); int success[10]={1,1,1,1,1,1,1,1,1,1}; int flag=1; FILE *fp; void setup(char inputBuffer[], char *args[],int *background) { int length,i,start, ct; ct = 0; length = read(STDIN_FILENO, inputBuffer, MAX_LINE); start = -1; if (length == 0) exit(0); if (length < 0){ perror("error reading the command"); exit(-1); } for (i = 0; i < length; i++) { switch (inputBuffer[i]){ case ' ': case '\t' : if(start != -1){ args[ct] = &inputBuffer[start]; ct++; } inputBuffer[i] = '\0'; start = -1; break; case '\n': if (start != -1){ args[ct] = &inputBuffer[start]; ct++; } inputBuffer[i] = '\0'; args[ct] = NULL; break; case '&': *background = 1; inputBuffer[i] = '\0'; break; default : if (start == -1) start = i; } } args[ct] = NULL; } void handle_SIGINT() { write(STDOUT_FILENO, buffer, strlen(buffer)); printf("COMMAND HISTORY:\n"); int i = nextPosition; int j; int counter=10; i = nextPosition; while(counter--) { printf("# "); for(j=0; j<CommandLenth[i]; ++j){ printf("%s ",history[i][j]); } printf("\n"); i = (i + 1) % 10; } printf("COMMAND->"); fflush(0); return; } void ProcessRCommand(char *args[]){ int i, j, count=10; char *newargs[MAX_LINE/2+1]; for(i=0; i<MAX_LINE/2+1; ++i) { newargs[i] = (char*)malloc((MAX_LINE/2+1)*sizeof(char)); } if (flag==1) { nextPosition = (nextPosition-1)%10; } history[nextPosition][0] = '\0'; if (args[1]==NULL){ i = (nextPosition + 9) % 10; for(j=0; j<CommandLenth[i]; ++j){ strcpy(newargs[j], history[i][j]); } newargs[j]=NULL; if (success[i]==1){ execvp(newargs[0], newargs); success[i]=0; printf("Wrong Instruction!\n"); } fp=fopen("/home/ieee/success.txt","r+"); if (fp == NULL) { printf("File open error.\n"); } int k=0; for (k=0;k<10;k++){fprintf(fp,"%d\n",success[k]);} fclose(fp); exit(0); } else{ /*Command "r x"*/ i = nextPosition; while(count--){ i = (i + 9) % 10; if (strncmp(args[1], history[i][0], 1) == 0){ for(j=0; j<CommandLenth[i]; ++j){ strcpy(newargs[j], history[i][j]); } newargs[j]=NULL; if (success[i]==1){ execvp(newargs[0], newargs); success[i]=0; printf("Wrong Instruction!\n"); } /*update*/ fp=fopen("/home/ieee/success.txt","r+"); if (fp == NULL) { printf("File open error."); } int k=0; for (k=0;k<10;k++){fprintf(fp,"%d\n",success[k]);} fclose(fp); exit(0); } } printf("No such instruction!\n"); } } int main(void) { char inputBuffer[MAX_LINE]; int background; char *args[MAX_LINE/2+1]; int count; int i, j; /*update*/ fp=fopen("/home/ieee/success.txt","r+"); if (fp == NULL) {printf("File open error.");} int k=0; for (k=0;k<10;k++){fprintf(fp,"%d\n",success[k]);} fclose(fp); for(i=0; i<10; ++i) { for(j=0; j<10; ++j) { history[i][j] = (char*)malloc(80*sizeof(char)); } } strcpy(buffer, "Caught Control C\n"); if (signal(SIGINT, handle_SIGINT)==SIG_ERR) printf("ERROR!\n"); while (1){ background = 0; printf("COMMAND->"); fflush(0); setup(inputBuffer, args, &background); i = 0; if (args[0] != NULL && strcmp(args[0],"r") != 0){ while(args[i] != NULL){ strcpy(history[nextPosition][i], args[i]); ++i; } CommandLenth[nextPosition] = i; nextPosition = (nextPosition + 1) % 10; } if (strcmp(args[0],"r") == 0){ if (args[1]==NULL){ /*"r" command only*/ i = (nextPosition + 9) % 10; if (success[i]==1){ for(j=0; j<CommandLenth[i]; ++j){ strcpy(history[nextPosition][j], history[i][j]); } CommandLenth[nextPosition] = j; nextPosition = (nextPosition + 1) % 10; flag =1; } if (success[i]==0) { printf("Wrong Instruction!\n"); flag=0; } } else{ /*"r x" command*/ i = nextPosition; count = 10; while(count--){ i = (i + 9) % 10; if (strncmp(args[1], history[i][0], 1) == 0){ if (success[i]==1) { for(j=0; j<CommandLenth[i]; ++j){ strcpy(history[nextPosition][j], history[i][j]); } CommandLenth[nextPosition] = j; nextPosition = (nextPosition + 1) % 10; flag=1; break; } if (success[i]==0) { printf("Wrong Instruction!\n"); flag=0; break; } } } } } pid_t pid = fork(); if(pid < 0){ printf("Fork failed.\n"); } else if(pid == 0){ /*Child Process*/ if(strcmp(args[0],"r") == 0){ ProcessRCommand(args); exit(0); } else{ execvp(args[0],args); int s = (nextPosition -1) % 10; success[s]=0; /*update the success.txt*/ fp=fopen("/home/ieee/success.txt","r+"); if (fp == NULL) {printf("File open error.");} int k=0; for (k=0;k<10;k++){fprintf(fp,"%d\n",success[k]);} fclose(fp); printf("Wrong Instruction!\n"); exit(0); } } else { /*Parent Process*/ if(background == 0){ wait(NULL); fp=fopen("/home/ieee/success.txt","r+"); fscanf(fp,"%d\n%d\n%d\n%d\n%d\n%d\n%d\n%d\n%d\n%d\n",&success[0],&success[1],&success[2],&success[3],&success[4],&success[5],&success[6],&success[7],&success[8],&success[9]); fclose(fp); } else{ setup(inputBuffer, args, &background); /*Parent process will not wait for the child*/ /*read the success.txt and update the success array*/ fp=fopen("/home/ieee/success.txt","r+"); fscanf(fp,"%d\n%d\n%d\n%d\n%d\n%d\n%d\n%d\n%d\n%d\n",&success[0],&success[1],&success[2],&success[3],&success[4],&success[5],&success[6],&success[7],&success[8],&success[9]); fclose(fp); } } } }