new file

2.c

+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define MAX 60
+#define MAX_HISTORY_SIZE 10
+
+// History struct to store command history
+
+
+char* history[MAX_HISTORY_SIZE];
+int history_count = 0;
+
+// Read a line from stdin
+char *readcommand() {
+    char *line = (char*) malloc(sizeof(char) * MAX);
+    printf("$> ");
+    fgets(line, MAX, stdin);
+
+    size_t ln = strlen(line)-1;
+    if (line[ln] == '\n')
+        line[ln] = '\0';
+
+    return line;
+}
+
+// Split the line into tokens
+char **splitcommand(char *line) {
+    char delim[] = " ";
+    char *ptr = strtok(line, delim);
+    char **tokens = (char**) malloc(sizeof(char*) * MAX);
+    int index = 0;
+    while(ptr != NULL) {
+        tokens[index] = ptr;
+        index++;
+        ptr = strtok(NULL, delim);
+    }
+    tokens[index] = NULL; // Set the last element to NULL for execvp
+    return tokens;
+}
+
+// Add command to history
+void add_to_history(const char* command) {
+    if (history_count < MAX_HISTORY_SIZE) {
+        history[history_count] = strdup(command);
+        
+        history_count++;
+    } else {
+        free(history[0]);
+        int i;
+        for (i = 0; i < MAX_HISTORY_SIZE - 1; i++) {
+            history[i] = history[i + 1];
+        }
+        history[MAX_HISTORY_SIZE - 1] = strdup(command);
+        
+    }
+}
+
+// Write to file
+void writeBye(const char *filename) {
+    FILE *fptr;
+    // Opening file in writing mode
+    fptr = fopen(filename, "w");
+    // Exiting program
+    if (fptr == NULL) {
+        printf("Error!");
+        exit(1);
+    }
+    fprintf(fptr, "%s", "Bye!\n");
+    fclose(fptr);
+}
+
+int main(int argc, char** argv) {
+    if (argc < 2) {
+        printf("Please insert exitfile as an argument!\n");
+        return 1;
+    }
+
+    while (1) {
+        char *line;
+        char **tokens;
+        line = readcommand();
+        char* line_copy = strdup(line);
+        tokens = splitcommand(line_copy);
+
+        if (strcmp(tokens[0], "exit") == 0) {
+            writeBye(argv[1]);
+            exit(0);
+        } else if (strcmp(tokens[0], "history") == 0) {
+        add_to_history(line_copy);
+            int i;
+            for (i = 0; i < history_count; i++) {
+                printf("%d: %s\n", i + 1, history[i]);
+            }
+            continue;
+        } 
+else{
+        add_to_history(line); // Add the command to history
+}
+        if (fork() == 0) {
+            if (execvp(tokens[0], tokens) == -1) {
+                perror("The following error occurred: ");
+            }
+            exit(1);
+        } else {
+            wait(0);
+        }
+    }
+    return 0;
+}

3.c

+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define MAX 60
+#define MAX_HISTORY_SIZE 10
+
+// History struct to store command history
+
+
+char* history[MAX_HISTORY_SIZE];
+int history_count = 0;
+
+// Read a line from stdin
+char *readcommand() {
+    char *line = (char*) malloc(sizeof(char) * MAX);
+    printf("$> ");
+    fgets(line, MAX, stdin);
+
+    size_t ln = strlen(line)-1;
+    if (line[ln] == '\n')
+        line[ln] = '\0';
+
+    return line;
+}
+
+// Split the line into tokens
+char **splitcommand(char *line) {
+    char delim[] = " ";
+    char *ptr = strtok(line, delim);
+    char **tokens = (char**) malloc(sizeof(char*) * MAX);
+    int index = 0;
+    while(ptr != NULL) {
+        tokens[index] = ptr;
+        index++;
+        ptr = strtok(NULL, delim);
+    }
+    tokens[index] = NULL; // Set the last element to NULL for execvp
+    return tokens;
+}
+
+// Add command to history
+void add_to_history(const char* command) {
+    if (history_count < MAX_HISTORY_SIZE) {
+        history[history_count] = strdup(command);
+        
+        history_count++;
+    } else {
+        free(history[0]);
+        int i;
+        for (i = 0; i < MAX_HISTORY_SIZE - 1; i++) {
+            history[i] = history[i + 1];
+        }
+        history[MAX_HISTORY_SIZE - 1] = strdup(command);
+        
+    }
+}
+
+// Write to file
+void writeBye(const char *filename) {
+    FILE *fptr;
+    // Opening file in writing mode
+    fptr = fopen(filename, "w");
+    // Exiting program
+    if (fptr == NULL) {
+        printf("Error!");
+        exit(1);
+    }
+    fprintf(fptr, "%s", "Bye!\n");
+    fclose(fptr);
+}
+
+int main(int argc, char** argv) {
+    if (argc < 2) {
+        printf("Please insert exitfile as an argument!\n");
+        return 1;
+    }
+
+    while (1) {
+        char *line;
+        char **tokens;
+        line = readcommand();
+        char* line_copy = strdup(line);
+        tokens = splitcommand(line_copy);
+
+        if (strcmp(tokens[0], "exit") == 0) {
+            writeBye(argv[1]);
+            exit(0);
+        } else if (strcmp(tokens[0], "history") == 0) {
+        add_to_history(line_copy);
+            int i;
+            for (i = 0; i < history_count; i++) {
+                printf("%d: %s\n", i + 1, history[i]);
+            }
+            continue;
+        } 
+        else if (tokens[0][0] == '!') {
+            int index = atoi(tokens[0] + 1);
+            if (index > 0 && index <= history_count) {
+                add_to_history(history[index - 1]); // Add the command to history
+                tokens = splitcommand(history[index - 1]); // Split the command into tokens
+            } else {
+                printf("Invalid history index\n");
+                continue;
+            }
+        } 
+else{
+        add_to_history(line); // Add the command to history
+}
+        if (fork() == 0) {
+            if (execvp(tokens[0], tokens) == -1) {
+                perror("The following error occurred: ");
+            }
+            exit(1);
+        } else {
+            wait(0);
+        }
+    }
+    return 0;
+}

4.c

+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define MAX 60
+#define MAX_HISTORY_SIZE 10
+
+// History struct to store command history
+
+
+char* history[MAX_HISTORY_SIZE];
+int history_count = 0;
+
+// Read a line from stdin
+char *readcommand() {
+    char *line = (char*) malloc(sizeof(char) * MAX);
+    printf("$> ");
+    fgets(line, MAX, stdin);
+
+    size_t ln = strlen(line)-1;
+    if (line[ln] == '\n')
+        line[ln] = '\0';
+
+    return line;
+}
+
+// Split the line into tokens
+char **splitcommand(char *line) {
+    char delim[] = " ";
+    char *ptr = strtok(line, delim);
+    char **tokens = (char**) malloc(sizeof(char*) * MAX);
+    int index = 0;
+    while(ptr != NULL) {
+        tokens[index] = ptr;
+        index++;
+        ptr = strtok(NULL, delim);
+    }
+    tokens[index] = NULL; // Set the last element to NULL for execvp
+    return tokens;
+}
+
+// Add command to history
+void add_to_history(const char* command) {
+    if (history_count < MAX_HISTORY_SIZE) {
+        history[history_count] = strdup(command);
+        
+        history_count++;
+    } else {
+        free(history[0]);
+        int i;
+        for (i = 0; i < MAX_HISTORY_SIZE - 1; i++) {
+            history[i] = history[i + 1];
+        }
+        history[MAX_HISTORY_SIZE - 1] = strdup(command);
+        
+    }
+}
+
+// Write to file
+void writeBye(const char *filename) {
+    FILE *fptr;
+    // Opening file in writing mode
+    fptr = fopen(filename, "w");
+    // Exiting program
+    if (fptr == NULL) {
+        printf("Error!");
+        exit(1);
+    }
+    fprintf(fptr, "%s", "Bye!\n");
+    fclose(fptr);
+}
+
+int main(int argc, char** argv) {
+    if (argc < 2) {
+        printf("Please insert exitfile as an argument!\n");
+        return 1;
+    }
+
+    while (1) {
+        char *line;
+        char **tokens;
+        line = readcommand();
+        char* line_copy = strdup(line);
+        tokens = splitcommand(line_copy);
+
+        if (strcmp(tokens[0], "exit") == 0) {
+            writeBye(argv[1]);
+            exit(0);
+        } else if (strcmp(tokens[0], "history") == 0) {
+         if (tokens[1]!=NULL && strcmp(tokens[1], "-del") == 0) {
+                int index = atoi(tokens[2]);
+                if (index > 0 && index <= history_count) {
+                    free(history[index - 1]); // Free the memory allocated for the command
+                    int i;
+                    for (i = index - 1; i < history_count - 1; i++) {
+                        history[i] = history[i + 1]; // Shift the remaining commands in the array
+                    }
+                    history_count--;
+                    continue;
+                } else {
+                    printf("Invalid history index\n");
+                    continue;
+                }
+            }
+            else{
+        add_to_history(line_copy);
+            int i;
+            for (i = 0; i < history_count; i++) {
+                printf("%d: %s\n", i + 1, history[i]);
+            }
+            continue;
+        } 
+        }
+        else if (tokens[0][0] == '!') {
+            int index = atoi(tokens[0] + 1);
+            if (index > 0 && index <= history_count) {
+                add_to_history(history[index - 1]); // Add the command to history
+                tokens = splitcommand(history[index - 1]); // Split the command into tokens
+            } else {
+                printf("Invalid history index\n");
+                continue;
+            }
+        } 
+else{
+        add_to_history(line); // Add the command to history
+}
+        if (fork() == 0) {
+            if (execvp(tokens[0], tokens) == -1) {
+                perror("The following error occurred: ");
+            }
+            exit(1);
+        } else {
+            wait(0);
+        }
+    }
+    return 0;
+}