This is a humble and simple implementation of a UNIX command line interpreter.
Olaf can interpret and execute command line arguments read from the standard input. It reads line by line from a file or the terminal line. It then interprets the lines and executes it if the line is a valid command.
All the files are to be compiled on an Ubuntu 14.04 LTS machine with:
$ gcc -Wall -Werror -Wextra -pedantic *.c -o olaf
Once compiled, to start the program, run:
$ ./olaf
To exit the program, run:
$ Olaf $ exit
The Olaf shell supports most shell commands, such as cat, pwd, ls -la and more.
The following built-ins are supported by the Olaf shell:
env- Print the current environmentsetenv VARIABLE VALUE- Initialize a new environment VARIABLE with VALUE, or modify an existing VARIABLE with VALUEunsetenv VARIABLE- Remove an environment VARIABLE
Olaf shell will exit with status 0 unless status is specified with syntax exit VALUE.
| Function Name | Description |
|---|---|
| parse_line | Parses the command line looking for commands and argumements. |
| create_Child | Forks the current process in order to execute another program. |
| tokenize | Separates a string in to an array of tokens based on a delimiter passed to the function. |
| count_token | Counts how many tokens are on a given string that is separated by a delimeter. |
| find_path | Looks through the environmental variables untill it finds the PATH variable, It then returns the index of its possition. |
| tokenize_path | Separates the PATH variable into separate strings each containing a directory in the PATH. |
| search_directories | Looks through directories stored in path_tokens for a specifc file name which represents a command. |
| build_path | Combines two strings, one representing the path directory and the other representing the command file. |
| _strcmp | Compares two strings and if they match the function returns 0. |
| _strdup | Duplicates a string. |
| print_str | Prints a string character by character. |
| cd_b | Changes the current working directory to the parameter passed to the command cd. |
| env_b | Prints all environmental variables available in the current shell. |
| check_built_ins | Checks if a command exitst as a builtin funcition and then it returns a pointer to the right function. |