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#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <sys/wait.h>
#include <stdio.h>

#define MAXLINE 100

static void sig_int(int);

int main() {
    char buf[MAXLINE];
    pid_t pid;
    int status;

    if(signal(SIGINT, sig_int) == SIG_ERR) {
        fprintf(stderr, "signal error.\n");
        return -1;
    }

    printf("%% ");
    while(fgets(buf, MAXLINE, stdin) != NULL) {
        if(buf[strlen(buf)-1] == '\n')
            buf[strlen(buf)-1] = 0;
        if((pid = fork()) < 0) {
            fprintf(stderr, "fork error.\n");
            return -1;
        } else if(pid == 0) {
            execlp(buf, buf, (char*)0);
            return 0;
        }

        if((pid=waitpid(pid, &status, 0)) < 0) {
            fprintf(stderr, "waitpid error.");
            return -1;
        }

        printf("%% ");
    }

    return 0;
}

void sig_int(int signo) {
    printf("interrupt\n%% ");
}