slip8_2.c

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

#define MAX_CMD_LEN 1024
#define MAX_ARGS 100

void execute_command(char **args) {
    pid_t pid = fork();
    if (pid < 0) {
        perror("Fork failed");
        exit(EXIT_FAILURE);
    } else if (pid == 0) {
        if (execvp(args[0], args) < 0) {
            perror("Execution failed");
            exit(EXIT_FAILURE);
        }
    } else {
        wait(NULL);
    }
}

void tokenize_input(char *input, char **args) {
    int index = 0;
    char *token = strtok(input, " \n");
    while (token != NULL) {
        args[index++] = token;
        token = strtok(NULL, " \n");
    }
    args[index] = NULL;
}

void search_command(char *mode, char *filename, char *pattern) {
    if (mode == NULL || filename == NULL || pattern == NULL) {
        fprintf(stderr, "Usage: search <f|c> <filename> <pattern>\n");
        return;
    }

    FILE *file = fopen(filename, "r");
    if (!file) {
        perror("File open failed");
        return;
    }

    char line[1024];
    int found = 0;
    int count = 0;

    while (fgets(line, sizeof(line), file)) {
        if (strstr(line, pattern)) {
            if (strcmp(mode, "f") == 0) {
                printf("%s", line);
                found = 1;
                break;
            } else if (strcmp(mode, "c") == 0) {
                char *ptr = line;
                while ((ptr = strstr(ptr, pattern)) != NULL) {
                    count++;
                    ptr++;
                }
            }
        }
    }

    if (strcmp(mode, "c") == 0) {
        printf("Total occurrences: %d\n", count);
    } else if (strcmp(mode, "f") == 0 && !found) {
        printf("Pattern not found.\n");
    }

    fclose(file);
}

int main() {
    char input[MAX_CMD_LEN];
    char *args[MAX_ARGS];

    while (1) {
        printf("myshell$ ");
        if (fgets(input, sizeof(input), stdin) == NULL) {
            perror("fgets failed");
            continue;
        }

        if (strlen(input) <= 1) continue;

        tokenize_input(input, args);

        if (args[0] == NULL) continue;

        if (strcmp(args[0], "exit") == 0) {
            exit(0);
        } else if (strcmp(args[0], "cd") == 0) {
            if (args[1] == NULL) {
                fprintf(stderr, "cd: missing argument\n");
            } else {
                if (chdir(args[1]) != 0) {
                    perror("cd failed");
                }
            }
        } else if (strcmp(args[0], "search") == 0) {
            search_command(args[1], args[2], args[3]);
        } else {
            execute_command(args);
        }
    }

    return 0;
}