Merge pull request #57 from janevers-sys/main

src/userland/cli/head.c

@@ -0,0 +1,54 @@
+// Copyright (c) 2026 janevers (https://github.com/janevers-sys)
+// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
+// This header needs to maintain in any file it is present in, as per the GPL license terms.
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[]) {
+    if (argc == 2) {
+        if(strcmp(argv[1], "--help")) {
+            printf("-This command reads from the front of the file\n");
+            printf("-Use: tail [-n] [-number of lines] [file]\n");
+            return 0;
+        }
+        //print everything
+        FILE *fp = fopen(argv[1], "r");
+        if (fp == NULL) {
+            printf("File not found\n");
+            return 1;
+        }
+        char buf[1024];
+        while (fgets(buf, sizeof(buf), fp)) {
+            printf("%s", buf);
+        }
+        fclose(fp);
+        return 0;
+    }
+
+    if (argc == 4 && strcmp(argv[1], "-n") == 0) {
+        int lines = atoi(argv[2]);
+        if (lines <= 0) {
+            printf("Number of lines must be positive\n");
+            return 1;
+        }
+
+        FILE *fp = fopen(argv[3], "r");
+        if (fp == NULL) {
+            printf("File not found\n");
+            return 1;
+        }
+
+        char buf[1024];
+        while (lines > 0 && fgets(buf, sizeof(buf), fp)) {
+            printf("%s", buf);
+            lines--;
+        }
+
+        fclose(fp);
+        return 0;
+    }
+
+    printf("Wrong flag, --help for more info\n");
+    return 1;
+}

src/userland/cli/help.c

@@ -39,6 +39,10 @@ int main(int argc, char **argv) {
     printf("exit           - Exit the terminal\n");
     printf("net            - Network tools\n");
     printf("time <cmd>     - Measure command execution time\n");
+    printf("find           - find files or dol")
+    printf("rev            - Reverse a string or file\n");
+    printf("head           - print lines from the top down\n");
+    printf("tail           - print lines from te bottom up\n");
     printf("\nHint: Use Ctrl+C to force quit any running application.\n");
     return 0;
 }

src/userland/cli/rev.c

@@ -0,0 +1,48 @@
+// Copyright (c) 2026 janevers (https://github.com/janevers-sys)
+// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
+// This header needs to maintain in any file it is present in, as per the GPL license terms.
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+// reverse function
+void reverse(char *str) {
+    int len = strlen(str);
+    for (int i = 0; i < len / 2; i++) {
+        char tmp = str[i];
+        str[i] = str[len - 1 - i];
+        str[len - 1 - i] = tmp;
+    }
+}
+
+int main(int argc, char *argv[]) {
+    // check if there are too much flags
+    if (argc != 2) {
+        printf("Wrong input, use --help for more info\n");
+        return 1;
+    }
+    if (argc == 2 && strcmp(argv[1], "--help") == 0) {
+        printf("Reverses the contents of a file or text\n");
+        printf("Usage: rev [file]\n");
+        return 0;
+    }
+
+    FILE *fp = fopen(argv[1], "r");
+    // check if the argument is a file or not by opening it
+    if (fp == NULL) {
+        reverse(argv[1]);
+        printf("%s\n", argv[1]);
+        return 0;
+    }
+    // reverse if flag is a file
+    char line[1024];
+    while (fgets(line, sizeof(line), fp)) {
+        line[strcspn(line, "\n")] = '\0';
+        reverse(line);
+        printf("%s\n", line);
+    }
+    fclose(fp);
+    return 0;
+}

src/userland/cli/tail.c

@@ -0,0 +1,68 @@
+// Copyright (c) 2026 janevers (https://github.com/janevers-sys)
+// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
+// This header needs to maintain in any file it is present in, as per the GPL license terms.
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[]) {
+    // print all lines
+    if (argc == 2) {
+        if (strcmp(argv[1], "--help") == 0) {
+            printf("-This command reads from the back of the file\n");
+            printf("-Use: tail [-n] [-number of lines] [file]\n");
+            return 0;
+        }
+        FILE *fp = fopen(argv[1], "r");
+        if (fp == NULL) {
+            printf("File not found\n");
+            return 1;
+        }
+        char buf[1024];
+        while (fgets(buf, sizeof(buf), fp)) {
+            printf("%s", buf);
+        }
+        fclose(fp);
+        return 0;
+    }
+    // only print last lines 
+    if (argc == 4 && strcmp(argv[1], "-n") == 0) {
+        int lines = atoi(argv[2]);
+        if (lines <= 0) {
+            printf("Number of lines must be positive\n");
+            return 1;
+        }
+
+        FILE *fp = fopen(argv[3], "r");
+        if (fp == NULL) {
+            printf("File not found\n");
+            return 1;
+        }
+
+        // count total lines
+        int count = 0;
+        char buf[1024];
+        while (fgets(buf, sizeof(buf), fp)) {
+            count++;
+        }
+
+        // back to start of file
+        fseek(fp, 0, SEEK_SET);
+
+        // check if lines are the end lines
+        int skip = count - lines;
+        int i = 0;
+        while (fgets(buf, sizeof(buf), fp)) {
+            if (i >= skip) {
+                printf("%s", buf);
+            }
+            i++;
+        }
+
+        fclose(fp);
+        return 0;
+    }
+
+    printf("Wrong flag, --help for more info\n");
+    return 1;
+}