In this project, we created a simple command line shell for UNIX and Linux called bish, short for bishounen (Japanese for 'pretty boy').
It is also a recursive acronym for Bish, It's a SHell.
At the end of this project, we are expected to be able to explain to anyone, without the help of Google:
- 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
- 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"?
Leo Byeon - https://github.com/leobyeon
Jenn Ogden - https://github.com/jogden4195
- Must be able to compile with gcc 4.8.4 using the flags -Wall -Werror -Wextra and -pedantic
- All files should follow Betty style and document guidelines
- No more than 5 functions per file
- Header files should be include guarded
| File | Description |
|---|---|
| bish.h | The header file for our project. It contains all of the prototypes, libraries, and structs necessary to run our main function. |
| main.c | This function generates our shell prompt and executes the user's commands. |
| array_maker.c | This file contains the function "array_maker", used in the main. |
| AUTHORS | This is the authors' page for our project. |
| getenv.c | This file contains the function "_getenv", used in the main. |
| _printf.c | This file contains the self_written function "_printf", used in the main. |
| print_number.c | This file contains the function "print_number", used in _printf. |
| putchar.c | This file contains the function "_putchar", used in _printf. |
| puts.c | This file contains the function "_puts", used in _printf. |
| README.md | This is the file you're reading right now! :) |
| replace_arg.c | This file contains the function "replace_arg", used in the main. |
| set_array.c | This file contains the function "set_array", used in the main. |
| strcmp.c | This file contains the function "_strcmp", used in the main. |
| strcpy.c | This file contains the function "_strcpy", used in set_array. |
| strlen.c | This file contains the function "_strlen", used in the main. |
| Function | Description | Arguments | Return Value | Prototype |
|---|---|---|---|---|
| main | Brings up a UNIX command line interpreter. Refer to How To Use |
None | 0 upon success | int main(void) |
| array_maker | Creates an array that will store the user's commands | char *usr_cmd | char **argv | char **array_maker(char *usr_cmd) |
| _strcmp | Compares two strings | char *str1, char *str2 | The difference between str1 and str2 | int _strcmp(char *str1, char *str2) |
| _strlen | Gets the length of a string | char *str | The length of the string | int _strlen(char *str) |
| _strcpy | Copies a source string to a destination string | char *dest, char *src | A pointer to the destination string | char _strcpy(char *dest, char *src) |
| _getenv | Gets the value of the environment variable | const char *name | Location of the matching variable if success; 0 if not found | char *_getenv(const char *name) |
| _printf | Prints out a string, integer, and/or character. | const char *format, ... | 0 upon success | int _printf(const char *format, ...) |
| _puts | Prints out a string | char *str | none | void _puts(char *str) |
| _putchar | Prints out a character | char c | 0 upon success | int _putchar(char c) |
| print_number | Prints out a number | int n | 0 upon success | int print_number(int n) |
| _env | Prints out the environment variable | none | none | void _env(void) |
| replace_arg | Replaces shell variables with the pathway to their executables | char *argv | Argv array with replaced variable in it | char *replace_arg(char *argv) |
| set_array | Sets the user's commands into newly made argv array | char *tok, char **cmd_array | none | void set_array(char *tok, char **cmd_array) |
$ git clone [repository link]
$ gcc -Wall -Werror -Wextra -pedantic *.c -o bish
$ ./bish
[enter *~b i s h~* commands]
All commands for the bish shell follow this syntax: command_name {arguments}, where command_name is the name of the command you want to execute (e.g. ls, echo, etc.) and {arguments} are the arguments you are giving to that command. For example,
echo "Hello World"
in the above command, echo is the name of the command we are trying to execute and "Hello World" is the argument we are feeding into the echo command.
| Command | What It Does |
|---|---|
| ls | Displays files and directories in current working directory. |
| cd | Changes directory. |
| echo | Prints out arguments to standard output. |
| cat | Prints out content of a file to standard output. |
| chgrp | Changes file group ownership. |
| chmod | Changes file access permissions. |
| chown | Changes file owner and group. |
| cp | Copies files and directories. |
| date | Prints or sets the system data and time. |
| dd | Converts and copies a file. |
| df | Reports filesystem disk space usage. |
| dmesg | Prints or controls the kernel message buffer. |
| env | Prints out list of all environment variables. |
| exit | Exits out of *~ b i s h ~*. |
| false | Does nothing, unsuccessfully. |
| hostname | Shows or sets the system's host name. |
| kill | Sends signals to processes. |
| ln | Makes links between files. |
| login | Begins a session on the system. |
| mkdir | Makes directories. |
| mknod | Makes block or character special files. |
| more | Pages through text. |
| mount | Mounts a filesystem. |
| mv | Moves and/or renames a file. |
| ps | Reports process status. |
| pwd | Prints the name of the current working directory. |
| rm | Removes files or directories. |
| rmdir | Removes empty directories. |
| sed | The 'sed' stream editor. |
| sh | A POSIX compatible command shell. |
| su | Changes user's ID. |
| true | Does nothing, successfully. |
| uname | Prints system information. |
To exit out of the bish shell, simply enter the command
exit
To exit out of a process, just press ctrl d.
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