⚔️ IRON shell

• 💻 Shell's are programs which provide command line interface to prefrom tasks, or in true sense they invoke execution of other programs. IRON here means hard/strong. This Shell inherits alot similar functionality as provided by many shells in market like bash, zsh.

• 😄 Fun Fact: Windows command prompt is world's most horrible shell program.

😎 UNIX Ideaology

• UNIX is made on basis of writing various programs such that each one of them can executes, handle and manage one particular task completely. In-order to achieve execution of complicated task, it is broken in sub-task and each sub-task is handled independently by the programs written and execution happens concurrently with each subtask I/O connected using PIPES.

• UNIX assumes everthing to be file (there are no drives, even folder/directory are files !!). The program execution can make use of file for I/O purpose. This is made possible using I/O REDIRECTION to files.

🔧 Installation Building IRON-shell executable

• Install for github UI, or by any command line interface with following commands

    $ git clone https://github.com/kishanpatel22/IRON-shell
    $ cd IRON-shell

• Run the following commands to create the executable file and start the shell

    $ make
    $ ./iron-shell

• Tip : use make clean to clean all the objects files created by make

🎯 Example regarding the features and usage

• The video contains a small demo of how to user the command line interface

  

📦 FEATURES OF IRON-SHELL

✴️ Build in IRON-Shell commands

• Support to build in iron-shell commands include the following things

  Command	Significance
  cd	command to change the current working directory
  exit	to exit the shell
  fg	to run any fore-ground process
  bg	run any background process

• Support to signals for the iron-shell

  Signal	Significance
  control-c	terminates the currently executing program / process
  control-z	suspends the execution of the currently running program / processes
  control-d	to exit from the iron-shell prompt

✴️ PIPES, RIDRECTION and STOPPING/RESUMING of processes

• Support to unix pipelining, redirection I/O with files and suspension for processes in iron-shell background.

• Examples for OUTPUT and INPUT Redirection

    /home/kishan/code/shell
    ISHELL >> wc < satellite_data.txt > file.txt

    /home/kishan/code/shell
    ISHELL >> cat file.txt
    864000  6912000 77817099 satellite_data.txt

• Examples for Pipelining

    /home/kishan/code/C++_codes
    ISHELL >> ls -l | grep ^d | sort   
    drwxr-xr-x 21 kishan kishan  4096 Feb  9 22:14 DSA
    drwxr-xr-x  2 kishan kishan  4096 Jan 10 21:04 Makefile
    drwxr-xr-x  2 kishan kishan  4096 Jan 11 15:04 cmake_demo
    drwxr-xr-x  2 kishan kishan  4096 Mar  7 19:52 pavan
    drwxr-xr-x  2 kishan kishan  4096 May 15  2020 cplusplus
    drwxr-xr-x  5 kishan kishan  4096 Aug 24  2020 TOC
    drwxr-xr-x  8 kishan kishan  4096 Jan  2 22:24 OOPS
    
    /home/kishan/code/C++_codes
    ISHELL >> ls -l | grep ^d | sort | head -n 3 
    drwxr-xr-x 21 kishan kishan  4096 Feb  9 22:14 DSA
    drwxr-xr-x  2 kishan kishan  4096 Jan 10 21:04 Makefile
    drwxr-xr-x  2 kishan kishan  4096 Jan 11 15:04 cmake_demo

    /home/kishan/code/C++_codes
     ISHELL >> ls -l | grep ^d | sort | head -n 3 | wc > new_data.txt
    
    /home/kishan/code/C++_codes
     ISHELL >> cat new_data.txt
          3      27     165

• Examples for Background process

    /home/kishan/code/shell
    ISHELL >> firefox &
    
    /home/kishan/code/shell
    ISHELL >> echo I can run next command
    I can run next command

    /home/kishan/code/shell
    ISHELL >> jobs

    [1]	+ 29020 running	firefox

• Example of signal handling and jobs

    /home/kishan/code/shell
    ISHELL >> ping www.google.com | grep ttl
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=1 ttl=120 time=5.88 ms
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=2 ttl=120 time=8.36 ms
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=3 ttl=120 time=8.82 ms
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=4 ttl=120 time=8.42 ms
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=5 ttl=120 time=8.50 ms
    ^Z
     [1]	+ 28924 stopped	grep
         	+ 28923 stopped	ping
    
    /home/kishan/code/shell
     ISHELL >> jobs
    
     [1]	+ 28924 stopped	grep
         	+ 28923 stopped	ping
    
    /home/kishan/code/shell
     ISHELL >> fg 
    
     [1]	+ 28924 running	grep
         	+ 28923 running	ping
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=6 ttl=120 time=8.48 ms
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=7 ttl=120 time=8.62 ms
    64 bytes from bom12s04-in-f4.1e100.net (216.58.203.4): icmp_seq=8 ttl=120 time=10.4 ms
    ^C

    /home/kishan/code/shell
     ISHELL >>