myshell's Introduction

MyShell

Author: Ze Sheng (Owen Sanazas)

Source Files

myshell.c
shell-behaviour.c
shell-behaviour.h
job.c
job.h
utils.c
utils.h

Progress

✓ - Finished
O - In progess
? - Have problem
blank - Not started

Section	State
ctrl + c	✓
ctrl + z	✓
Non-interactive mode	✓
Command parser	✓
File redirection	✓
multi-lvl pipeline	✓
job struct	✓
jobList Linkedlist	✓
All job helper funcs	✓
Bultin cmd: jobs	✓
Bultin cmd: fg	✓
Bultin cmd: bg	✓
Memory leaks check	✓
Invalid R/W check	✓
Zombie processes check	✓
Foreground check	✓
Background check	✓

Overview of work accomplished

This shell can be run in the non-interactive mode successfully.
All commands that are not job control builtins commands are handled by pipe. The standard input/output will be redirected and combining redirection is also supported.

We manage each job in a JobNode struct and use a linked list struct JobList to store all background jobs.

// Job Node
typedef struct JobNode {
    int pgid;                           // process group id of the current running job
    enum JobStatus status;              // Job status
    struct parsed_command *command;     // job's command
    struct JobNode *prev;               // Prev job pointer
    struct JobNode *next;               // Next job pointer
    int jobId;                          // Job priority
}JobNode;


// Linked-list structure to manage jobs
typedef struct JobList {
    JobNode *head;
    JobNode *tail;
    int jobCount;
}JobList;

Background processes (if existed) will be polled at the beginning of each loop of the shell.
The jobs can be managed through job control builtins (fg, bg, jobs).
The status of the jobs can be reported correctly.
Ctrl-C, Ctrl-D, Ctrl-Z, and other signal are handled correctly.

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