Magnush is the clone of the Bash shell. It is written in C, and supports various features that we can see in a traditional Bash shell.
git clone https://github.com/SwethaVipparla/Magnush.git
cd Magnush/make
./MagnushOnce the code is up and running, the commands for the included features can be executed. Multiple commands can also be entered in a single line, separated by ;. Random spaces and tabs in commands are accounted for too.
Magnush has a command prompt that is similar to the one in a Bash shell. The prompt is coloured and is displayed in the form of <username@system_name:curr_dir>.
The root directory is the one from which the shell is started.
Implemented in prompt.c
Magnush supports piping with commands. One or more commands can be piped using |, and any number of pipes are supported.
cat <filename.txt> | head -7 | tail -5Implemented in pipe.c
Magnush also provides for input/output redirection of commands. The output of commands can be redirected to another file or command instead of stdout, the input can be taken from a file other than stdin, or the output of a command can be appended to a file. These redirections are done using the <, >, and >> symbols.
Both input and output redirections can be used simultaneously too.
echo "hey" > output.txt
sort < output.txt > sorted.txtImplemented in redirection.c
Input/Output redirection can be implemented within command pipelines.
cat < in.txt | wc -l > lines.txt
Changes the current directory to another directory specified and displays an error if the specified directory does not exist.
., .., ~, and - are all valid directory names.
cd <path_to_destination_directory>Implemented in cd.c
Ouputs the path of the current working directory.
pwdImplemented in pwd.c
Prints the specified message on the terminal. It accounts for any random spaces and tabs.
echo <message>Implemented in echo.c
Lists all the files and directories in the given directory. It handles multiple directories as arguments. Flags can be used to provide more functionalities to the command.
ls <path_to_directory> -a: Lists all the files and directories in the given directory, along with symbolic links and hidden files and folders.
ls -a <path_to_directory> -l: Lists all the files and directories in the given directory with detailed information.
ls -l <path_to_directory> These flags can be used together in different orders while giving the intended output.
Implemented in ls.c
Diplays the history of the commands run. If no argument is specified, the last 10 commands are listed. The history persists even after the shell is exited.
history <no_of_commands>Implemented in history.c
Displays information about the process, including its PID, status, memory, and executable path.
pinfo <PID>Running just pinfo without any arguments will display information about the shell program.
Implemented in pinfo.c
Executes the given instruction multiple times. The first argument to the command specifies the number of times the following command is to be run.
repeat <no_of_times> <input_command>Implemented in repeat.c
Brings the running or stopped background job corresponding to the job number to the foreground and changes its state to running.
fg <job_number>Implemented in fgbg.c
Changes the state of a stopped background job to running (in the background). It has no effect on foreground processes and already running background processes.
bg <job_number>Implemented in fgbg.c
Prints a list of all currently running background processes spawned by the shell in alphabetical order of the command name, along with their job numbers, process IDs, and states (either running or stopped).
jobs-r: Prints only the running processes.
jobs -r-s: Prints only the stopped processes.
jobs -sThese flags can be used at the same time in different orders while giving the intended output.
Implemented in jobs.c
Takes the job number of a running job and sends the signal corresponding to signal numbersignal number to that process.
sig <job_number> <signal_number>Implemented in sig.c
Executes a particular command in fixed time interval for a certain period
replay -command <input_command> -interval <time_interval> -period <time_period>
All the flags here are required and can be implemented in any order. Background processes are also supported.
Implemented in replay.c
-n: The time interval in which to execute the command periodically.
All three commands run until the key q is pressed.
interrupt: Prints the number of times the CPU(s) has(ve) been interrupted by the keyboardcontroller (i8042 with IRQ 1).
baywatch -n <time_interval> interruptnewborn: Prints the PID of the process that was most recently created on the system.
baywatch -n <time_interval> newborndirty: Prints the size of the part of the memory that is dirty.
baywatch -n <time_interval> dirtyImplemented in baywatch.c
There are two kinds of processes that can be run in Magnush.
To run processes in the foreground, just enter the command and the process will start up.
Magush will wait for this process to complete and regain control when this process exits.
If the given command is not found, an error is displayed.
For example, vim and gedit are foreground processes.
<input_command>Implemented in process.c
To run processes in the background, enter an & after the command and the process will start up.
Magush will spawn the process and doesn't wait for it to exit. It will keep taking other user commands.
After the background process exits, the shell displays the exit status on the terminal.
<input_command> &or
<input_command>&
Implemented in process.c
Magnush allows the handling of signal, each of which serves a different purpose.
Implemented in signals.c
Pushes any currently running foreground job into the background and changes its state from running to stopped by sending the SIGTSTP. It has no effect on the shell if there is no foreground process running.
Interrupts any currently running foreground job by sending the SIGINT signal. It has no effect on the shell if there is no foreground process running.
Log the user out of the shell, without having any effect on the actual terminal.