diff --git a/README.md b/README.md
index 3612c40..4da7a9c 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,66 @@
+## external functions :
+---
+### readline :
+- readline
+- rl_clear_history
+- rl_on_new_line
+- rl_replace_line
+- rl_redisplay
+- add_history
+### files :
+- access
+- open
+- read
+- close
+- dup
+- dup2
+- pipe
+- stat : `int stat(const char *pathname, struct stat *statbuf);` returns information about a file, in the buffer pointed to by statbuf
+- lstat : `int fstat(int fd, struct stat *statbuf);` lstat() is  identical  to stat(), except that if pathname is a symbolic link, then it returns information about the link itself, not the file that it refers to
+- fstat : `int lstat(const char *pathname, struct stat *statbuf);` fstat() is identical to stat(), except that the file about which information is to be retrieved is specified by the file descriptor fd
+- unlink : `int unlink(const char *pathname);` unlink() deletes a name from the filesystem
+### process :
+- fork
+- wait
+- waitpid
+- wait3
+- wait4
+- exit
+### signals :
+- signal
+- sigaction
+- kill
+### directories :
+- getcwd : `char *getcwd(char *buf, size_t size);` returns a null-terminated string containing an absolute pathname that is the current working directory of the calling process
+- chdir : `int chdir(const char *path);` changes the current working directory of the calling process to the directory specified in path
+- execve : `int execve(const char *filename, char *const argv[], char *const envp[]);` executes the program pointed to by filename
+- opendir : `DIR *opendir(const char *name);` opens a directory stream corresponding to the directory name, and returns a pointer to the directory stream
+- readdir : `struct dirent *readdir(DIR *dirp);` returns a pointer to a dirent structure representing the next directory entry in the directory stream pointed to by dirp
+- closedir : `int closedir(DIR *dirp);` closes the directory stream associated with dirp
+### errors :
+- strerror : `char *strerror(int errnum);` returns a pointer to a string that describes the error code passed in the argument errnum
+- perror : `void perror(const char *s);` produces a message on standard error describing the last error encountered during a call to a system or library function
+### other :
+- printf
+- malloc
+- free
+- write
+
+- isatty
+- ttyname
+- ttyslot
+- ioctl
+- getenv
+- tcsetattr
+- tcgetattr
+- tgetent
+- tgetflag
+- tgetnum
+- tgetstr
+- tgoto
+- tputs
+
+
 ## sommaire :
 ---
 - [1. todo list :](#markdown-header-1-todo-list)