bishBOSH Shell

(Late Date of Completion: 7 December 2021)

Successfully Implemented Features:

• Semicolon separation (with aforementioned quotation mark functionality).
• Path directory method execution (including cd and exit).
  • For cd, arguments /, ., .., [child directory], simply cd and one-argument combinations of these arguments (e.g. ../../ are supported.
• Redirection and piping.

Bonus Features:

• Current directory shown in command line (not in reference to ~, unfortunately).
• Quotation marks to ignore delimiters (e.g. cd 'fol der')
• Multiple (consecutive) semicolons and spaces are allowed (e.g. ls ; ;;; ; ls -l executes ls;ls -l).
  • bash does not have exactly this semicolon functionality, but we thought it would be cool.
  • This applies for redirection and piping as well, HOWEVER there must be at least one space between the operators and surrounding arguments (e.g. ls|wc fails whereas ls | wc executes).

Unsuccessfully Attempted Features:

• Did not manage to immitate bash behaviour of showing current directory's relation to ~ directory.

Limitations:

• Current path has a maximum length of 100 chars.
• Redirection/piping requires at least one ' ' before and after the >, >>, < or | operator(s) for them to function.

Known Bugs/Issues:

• For some reason, performing ls | wc outputs a character count 1 greater than bash (e.g. bishBOSH ls | wc could output 6 6 49 when bash ls | wc would output 6 6 48)

struct dirs{char hdir[100]; char cdir[100]; char ddir[100];};
// Holds information about the home, current and display directory.

int strcount(char *str, char *sub);
// Counts the total instances of sub within str (e.x. strcount("helllo", "ll") = 2).

char *null_term(char *str);
// Changes newline terminated strings into null terminated strings (particularly useful for fgets()).

char *combine_args(char *line[], int delim_i);
// Combines line into a char * and replaces the argument which was at line[delim_i] with 0, effectively splitting this memory space into two usable strings.
// delim_i is only ever passed the index of "|" in a given line, as this is only used for piping.

int sep(char **str, char **src, char delim);
// Mimics strsep (or, more accurately, strtok) functionality, but also allows quotations to cancel out deliminators.

int exec_cd(char *line[], struct dirs *dir);
// Runs cd commands.

int exec_exit(char *line[]);
// Runs exit command.

int exec_redir(char *line[], struct dirs *dir);
// Attempts to handle redirection and piping before calling exec_func if necessary.

int exec_func(char *line[], struct dirs *dir);
// Runs all other individual commands.

int exec_all(char *line, struct dirs *dir);
// Parses through entire input, separates each command into character pointer arrays and calls exec_func.