head: implementation of the head command

Makefile

@@ -17,6 +17,8 @@ all:
 	@make -C luxfetch
 	@echo "\x1B[0;1;35m make\x1B[0m utilities/libctests"
 	@make -C libctests
+	@echo "\x1B[0;1;35m make\x1B[0m utilities/head"
+	@make -C head
 
 install:
 	@mkdir -p out
@@ -38,6 +40,8 @@ install:
 	@make install -C luxfetch
 	@echo "\x1B[0;1;35m make\x1B[0m install utilities/libctests"
 	@make install -C libctests
+	@echo "\x1B[0;1;35m make\x1B[0m install utilities/head"
+	@make install -C head
 
 clean:
 	@echo "\x1B[0;1;35m make\x1B[0m clean utilities/hello"
@@ -57,4 +61,6 @@ clean:
 	@echo "\x1B[0;1;35m make\x1B[0m clean utilities/luxfetch"
 	@make clean -C luxfetch
 	@echo "\x1B[0;1;35m make\x1B[0m clean utilities/libctests"
-	@make clean -C libctests
+	@make clean -C libctests
+	@echo "\x1B[0;1;35m make\x1B[0m clean utilities/head"
+	@make clean -C head

head/head.c

@@ -0,0 +1,76 @@
+/*
+ * luxOS - a unix-like operating system
+ * Omar Elghoul, 2024
+ * 
+ * head: Implementation of the head command
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+
+int n = 10;
+int totalLines = 0;
+char *line = NULL;
+
+int head(FILE *input) {
+    int errors = 0;
+
+    if(line) free(line);
+    line = NULL;
+    size_t lineSize = 4096;
+
+    while(totalLines < n) {
+        getline(&line, &lineSize, input);
+        if(!line) {
+            errors++;
+        } else {
+            printf("%s", line);
+            totalLines++;
+        }
+
+        if(feof(input)) break;
+    }
+
+    return errors;
+}
+
+int main(int argc, char **argv) {
+    opterr = 0;
+    int opt;
+
+    while((opt = getopt(argc, argv, "n:")) != -1) {
+        if(opt == 'n') {
+            n = atoi(optarg);
+        } else if(opt == ':') {
+            fprintf(stderr, "%s: option -%c requires an operand\n", argv[0], optopt);
+            return -1;
+        } else {
+            fprintf(stderr, "%s: invalid option -- %c\n", argv[0], optopt);
+            fprintf(stderr, "usage: %s [-u] [file ...]\n", argv[0]);
+            return -1;
+        }
+    }
+
+    int retval = 0;
+    FILE *input;
+
+    if(optind < argc) {
+        for(int i = optind; i < argc; i++) {
+            input = fopen(argv[i], "r");
+            if(!input) {
+                fprintf(stderr, "%s: cannot open %s for reading\n", argv[0], argv[i]);
+                retval++;
+                continue;
+            }
+
+            retval += head(input);
+        }
+    } else {
+        input = stdin;
+        retval += head(input);
+    }
+
+    return retval;
+}