C-shell

headers.h

contails all header files and extern and global variables

Specification 1:

prompt.c

 Display requirement is coverd in this file

used getpwuid to get the user name
used uname to get nodename ie system name
found relative path between from where the shell was started and where the proess cureently is and printing accordingly
declaration is in prompt.h

Specification 2: Builtin commands

pwd.c

pwd.c contains implementation of pwd command  which prints name of current/working directory
declaration is in pwd.h

cd.c

cd.c contains implementation of cd command
declaration is in cd.h

echo.c

echo.c contains implementation of cd command, managed empty spaces
declaration is in echo.h

Specification 3: ls command

ls.c

ls.c contains implementation of ls command
Implemented the ls command with its two flags “-a” and “-l”. You should be able to handle all
the following cases also:(used getopt)
● ls
● ls -a
● ls -l
● ls .
● ls ..
● ls ~
● ls -a -l
● ls -la / ls -al
● ls <Directory/File_name>
● ls -<flags> <Directory/File_name>
declaration is in ls.h

Specification 4: System commands with and without arguments

systemCommands.c

contains implementation for foreground and background processes that are system commands
declaration of functions in systemCommand.h
parent waits for foreground not for baground process.
used fork,execvp,wait

Specification 5: pinfo command

pinfo.c

contains impementation of pinfo command.got all information from proc/<pid>/.. files
declaration in pinfo.h

Specification 6: Finished Background Processes

systemCommands.c

check_baground_process(), handler(...) contains implementation  to print exit status of baground process whenever it exits.used sigaction.

Specification 7: repeat Command

repeat.c

contains implementation of repeat .
The command is responsible for executing the given
instruction multiple times. The first argument to the command specifies the number of
times the following command is to be run.

declaration in repeat.h

Specification 8: history

history.c

implement user defined history command.
declaration in history.h

Part two

Specification 1: Input/Output Redirection

execute.c

implemented in split_into_arguments,switch_input_output functions
used dup2()
An error message  displays if the input file does not exist.
The output file is created (with permissions ​0644​)if it does not already exist.
In case the output file already exists,it  overwrits in case of >​ and appends to in case of ​>>

Specification 2:Command Pipelines

execute.c

used dup2() ,pipes() 

Specification 3: I/O Redirection within Command Pipelines

execute.c

used dup2() ,pipes() 

Specification 4: User-defined Commands

jobs.c

formed a linked list to store 
void add_job(int pid);
void delete_jobs(int pid);
void print_jobs();
update_status(pid);
int get_process_id(int job_no);
This command prints a list of all currently running background processes spawned by the shell in alphabetical order of the command name, along with
their job number (a sequential number assigned by your shell), process ID and their state, which can either be r ​ unning​ or ​stopped​ . There may be flags specified
as well. If the flag specified is -r , then print only the running processes else if the flag is -s then print the stopped processes only.

sig

sig.c

Takes the job number (assigned by your shell) of a running job and sends the signal corresponding to s ​ ignal number​ to that process. The shell throws an error if no job with the given number exists

fg

fg.c

Brings the running or stopped background job corresponding to ​job number​ to the foreground, and changes its state to ​running .​The shell throws an error if no job with the given job number exists.

bg

bg.c

Changes the state of a stopped background job to running (in the background). The shell should throw an error if no background job corresponding to the
given job number exists, and do nothing if the job is already running in the background.

Specification 5: Signal Handling

In signaL.C

1. CTRL-Z It should push any currently running foreground job into the background, and change its state from running to stopped. This should have no effect on the shell if there is no foreground process running.
2. CTRL-C It should interrupt any currently running foreground job, by sending it the ​SIGINT​ signal. This should have no effect on the shell if there is no foreground process running.

GETLINE (exeute.c)

3. CTRL-D It should log you out of your shell, without having any effect on the actual terminal.

Bonus 1: replay :

Replay.c

Implemented a ‘replay’ command which executes a particular command in fixed time interval for a certain period.