diff --git a/builtins.c b/builtins.c
index 16265e7..882cfa0 100644
--- a/builtins.c
+++ b/builtins.c
@@ -72,6 +72,8 @@ void (*check_built_ins(char *str))(char *str)
 	builtin_t buildin[] = {
 		{"exit", exit_b},
 		{"env", env_b},
+		{"setenv", setenv_b},
+		{"unsetenv", unsetenv_b},
 		{"cd", cd_b},
 		{NULL, NULL}
 	};
diff --git a/hbtlib.c b/hbtlib.c
index f258edf..d332cb3 100644
--- a/hbtlib.c
+++ b/hbtlib.c
@@ -40,6 +40,39 @@ char *_strdup(char *src)
 	return (dest);
 }
 
+/**
+ * _realloc - reallocate a memory block
+ * @ptr: pointer to old block
+ * @old_size: old memory size
+ * @new_size: new memory size
+ * Return: pointer to new block, NULL when failed
+ */
+void *_realloc(void *ptr, unsigned int old_size, unsigned int new_size)
+{
+	char *p, *orig = (char *)ptr;
+	unsigned int i;
+
+	if (old_size == new_size)
+		return (ptr);
+	if (new_size == 0 && ptr != NULL)
+		return (NULL);
+	if (ptr == NULL)
+	{
+		p = malloc(new_size);
+		if (p == NULL)
+			return (NULL);
+	}
+	else
+	{
+		p = malloc(new_size);
+		if (p == NULL)
+			return (NULL);
+		for (i = 0; orig[i] != '\0' && i < new_size ; i++)
+			p[i] = orig[i];
+	}
+	return (p);
+}
+
 /**
  * print_str - Prints a string character by character.
  * @str: String to be printed. If the string is NULL it will print (null)
diff --git a/olaf.h b/olaf.h
index 2836480..e35bc4b 100644
--- a/olaf.h
+++ b/olaf.h
@@ -48,10 +48,17 @@ void (*check_built_ins(char *str))(char *str);
 void exit_b(char *str);
 void env_b(char *str);
 void cd_b(char *directory);
+void unsetenv_b(char *str);
+void setenv_b(char *str);
+int check_env(char *env);
+void modify_env(char *env, char *value);
+void add_env(char *env, char *value);
+void remove_env(char *env);
 
 /*Holberton library functions*/
 int _strcmp(char *s1, char *s2);
 char *_strdup(char *src);
+void *_realloc(void *ptr, unsigned int old_size, unsigned int new_size);
 void print_str(char *str, int new_line);
 
 #endif
diff --git a/setenv.c b/setenv.c
new file mode 100644
index 0000000..5b5fc8f
--- /dev/null
+++ b/setenv.c
@@ -0,0 +1,104 @@
+#include "olaf.h"
+
+/**
+ * setenv_b - Initialize a new environ variable, or modify an existing one
+ * @line: A string representing the input from the user.
+ */
+void setenv_b(char *line)
+{
+	int check, token_count = 0;
+	char **path_tokens;
+	const char *delim = "\n\t ";
+	char *env, *value;
+
+	path_tokens = token_interface(line, delim, token_count);
+	env = path_tokens[1], value = path_tokens[2];
+
+	check = check_env(env);
+	if (check == 1)
+		modify_env(env, value);
+	if (check == 0)
+		add_env(env, value);
+
+	double_free(path_tokens);
+}
+
+/**
+ * check_env - Check if an environ variable exists
+ * @env: Variable to be checked
+ * Return: 1 - found environ variable, 0 - not found
+ */
+int check_env(char *env)
+{
+	int i, j;
+
+	i = 0;
+	while (environ[i])
+	{
+		j = 0;
+		while (environ[i][j] == env[j])
+		{
+			j++;
+			if (environ[i][j] == '=' && !env[j])
+				return (1);
+		}
+		i++;
+	}
+	return (0);
+}
+
+/**
+ * modify_env - Modify environ variable
+ * @env: environ variable
+ * @value: environ variable value
+ */
+void modify_env(char *env, char *value)
+{
+	int index, i = 0, j = 0;
+
+	index = find_path(env);
+
+	for (i = 0; env[i]; i++)
+		environ[index][i] = env[i];
+
+	environ[index][i] = '=', i++;
+
+	for (j = 0; value[j]; i++, j++)
+		environ[index][i] = value[j];
+	environ[index][i] = '\0';
+}
+
+/**
+ * add_env - Add new environ variable
+ * @env: environ variable
+ * @value: environ variable value
+ */
+void add_env(char *env, char *value)
+{
+	int i = 0, j = 0, t = 0, count = 0, size;
+	char **new;
+
+	for (i = 0; environ[i]; i++)
+		count++;
+
+	new = _realloc(environ, sizeof(char *) * count, sizeof(char *) * (count + 2));
+	if (new == NULL)
+		return;
+	for (i = 0; i < count; i++)
+		new[i] = _strdup(environ[i]);
+	size = strlen(env) + strlen(value) + 2;
+	new[i] = malloc(sizeof(char) * size);
+	if (new[i] == NULL)
+		return;
+
+	for (j = 0; env[j]; j++)
+		new[i][j] = env[j];
+
+	new[i][j] = '=', j++;
+
+	for (t = 0; value[t]; j++, t++)
+		new[i][j] = value[t];
+	new[i][j] = '\0';
+	new[i + 1] = NULL;
+	environ = new;
+}
diff --git a/unsetenv.c b/unsetenv.c
new file mode 100644
index 0000000..1411200
--- /dev/null
+++ b/unsetenv.c
@@ -0,0 +1,53 @@
+#include "olaf.h"
+
+/**
+ * unsetenv_b - Remove an environ variable
+ * @line: A string representing the input from the user.
+ */
+void unsetenv_b(char *line)
+{
+	int check, token_count = 0;
+	char **path_tokens;
+	const char *delim = "\n\t ";
+	char *env;
+
+	path_tokens = token_interface(line, delim, token_count);
+	env = path_tokens[1];
+
+	check = check_env(env);
+	if (check == 0)
+	{
+		printf("unsetenv: %s: variable not found\n", env);
+		return;
+	}
+	if (check == 1)
+		remove_env(env);
+
+	double_free(path_tokens);
+}
+
+/**
+ * remove_env - Remove environ variable
+ * @env: environ variable
+ */
+void remove_env(char *env)
+{
+	int i = 0, j = 0, size = 0, index;
+	char **str;
+
+	for (i = 0; environ[i]; i++)
+		size++;
+	str = malloc(sizeof(char *) * size);
+	if (str == NULL)
+		return;
+
+	index = find_path(env);
+	for (i = 0; environ[i]; i++, j++)
+	{
+		if (i == index)
+			i++;
+		str[j] = _strdup(environ[i]);
+	}
+	str[j] = NULL;
+	environ = str;
+}