This project is the submission for OSN Assignment 2 and 3, 2022.
- Name: Arnav Negi
- Roll: 2021101112
- Branch: CSE
- GCC compiler
- Linux based OS ( built for Ubuntu 20.04)
To compile and run the shell, do the following:
- Enter the shell directory containing the makefile.
- Run make all.
- Run ./main
The project is built in a modular fashion. The included files are given below:
| File/Directory name | Function or purpose |
|---|---|
| main.c | Contains the driver code for the shell. Runs most of the basic functions including background processes and running commands from modules. Also initialises some variables. |
| inputs.c | Contains functions to deal with I/O and handle ';' and '&' in commands. |
| builtin | Contains code for the 3 builtin commands for specification 2 - cd (cd.c) pwd (workingdir.c) and echo (echo.c) |
| ls | Contains the code for the ls command for specification 3. |
| pinfo | Contains code for pinfo command for specification 5. |
| discover | Contains code for the discover command for specification 7. |
| history | Contains code for the history command along with the hidden ".history" file storing the command history. |
| helper | Contains helper functions such as prompt, input functions and autocomplete. |
| job_control | Contains functions that handle job control of the shell - fg, bg, jobs and sig. |
| signals | Contains functions handling signals sent by child processes or user keyboard inputs. |
| included.h | Contains all standard c library headers, data declarations and extern variables shared by all files |
| headers.h | Header file containing all include statements required. |
- Assumptions regarding buffer size for directory names and maximum number of background processes are taken. 200 characters for buffer sizes and 100 background processes at once.
- In command history, the commands "A ;B" and "A ; B" are treated differently due to lack of space between the semicolon and B.
- Running the command "vim &" seems to break the terminal because of unwanted I/O being sent to the driver code. Since all shells don't run "vim &" (they suspend the process immediately) I assume this command won't be required and vim will be used in foreground.
- ~ notation for home directory is not to be used with system programs and only with the programs given above.