• Who designed and implemented the original Unix operating system
• Who wrote the first version of the UNIX shell
• Who invented the B programming language (the direct predecessor to the C programming language)
• Who is Ken Thompson
• How does a shell work
• What is a pid and a ppid
• How to manipulate the environment of the current process
• What is the difference between a function and a system call
• How to create processes
• What are the three prototypes of main
• How does the shell use the PATH to find the programs
• How to execute another program with the execve system call
• How to suspend the execution of a process until one of its children terminates
• What is EOF / “end-of-file”?

• access (man 2 access)
• chdir (man 2 chdir)
• close (man 2 close)
• closedir (man 3 closedir)
• execve (man 2 execve)
• exit (man 3 exit)
• _exit (man 2 _exit)
• fflush (man 3 fflush)
• fork (man 2 fork)
• free (man 3 free)
• getcwd (man 3 getcwd)
• getline (man 3 getline)
• isatty (man 3 isatty)
• kill (man 2 kill)
• malloc (man 3 malloc)
• open (man 2 open)
• opendir (man 3 opendir)
• perror (man 3 perror)
• read (man 2 read)
• readdir (man 3 readdir)
• signal (man 2 signal)
• stat (__xstat) (man 2 stat)
• lstat (__lxstat) (man 2 lstat)
• fstat (__fxstat) (man 2 fstat)
• strtok (man 3 strtok)
• wait (man 2 wait)
• waitpid (man 2 waitpid)
• wait3 (man 2 wait3)
• wait4 (man 2 wait4)
• write (man 2 write)

gcc -Wall -Werror -Wextra -pedantic *.c -o hsh

=============

$ ./hsh
($) /bin/ls
hsh main.c shell.c
($)
($) exit
$`

**_strcmpdir** :  compares strings to find dir.
**find_command** :  finds command to execute in path routes.
**charput** :  writes the character like putchar.
**place** :  similar to puts in C.
**_strlen** :  string length.
**str_concat** :  concatenate strings.
**lookforslash** :  identify if first char is a '/'.
**compareExit** :  checks if user typed exit.
**compareEnv** :  checks if user typed env.
**execute_proc** :  receives command and args from getline to be executed.
**identify_string** :  returns pointer with folder address.
**prompt** :  infinite loop with fork to keep prompt going.
**controlC**: avoid program closing when pressing ctrl + c.
**main**: initialize program.

Git: Celestinah Odebunmi, Lawrence Ikhidero