Description

This is an implementation of the Linux shell in C shell. It supports basic terminal commands and some couple commands. It also uses networking and piping concepts to make the terminal more diverse and robust to commands from the user. This project was taken up as a part of the Operating Systems and Networks course at IIITH Monsoon '23 semester. The documentation for the shell is given below

Table of Contents

• warp Command
• peek Command
• pastevents Command
• proclore Command
• I/O Redirection
• Pipes
• Redirection along with Pipes
• activities Command
• ping Command
• fg and bg Commands
• neonate Command
• iMan Command

---

warp Command

Syntax:

warp [flags] [directory]

Flags:

• .: Current directory
• ..: Parent directory
• ~: Home directory
• -: Previous directory

Description: Changes the shell's working directory. Supports both absolute and relative paths.

Examples:

warp test          # Changes to /home/user/test
warp ../tutorial   # Changes to /home/user/tutorial
warp ~             # Changes to /home/user
warp -             # Changes to the previous directory

---

peek Command

Syntax:

peek [flags] [path]

Flags:

• -a: Show hidden files
• -l: Display extra information

Description: Lists files and directories in the specified directory. Supports flags for additional details and color-coded output.

Examples:

peek test              # Lists files and directories in /home/user/test
peek -a /usr/bin       # Lists hidden files in /usr/bin
peek -l ~              # Displays extra information in /home/user

---

pastevents Command

Syntax:

pastevents
pastevents purge
pastevents execute <index>

Description: Stores and retrieves the 15 most recent commands. 'purge' clears stored commands. 'execute' runs a command from the history.

Examples:

pastevents            # Displays the command history
pastevents purge      # Clears the command history
pastevents execute 3  # Executes the command at index 3

---

proclore Command

Syntax:

proclore [pid]

Description: Provides information about a process, including PID, status, process group, virtual memory, and executable path.

Examples:

proclore             # Displays information about the shell process
proclore 123         # Displays information about the process with PID 123

---

I/O Redirection

Syntax:

command > output_file
command >> output_file
command < input_file

Description: Redirects command output to a file using >, appends with >>, and takes input from a file using <.

Examples:

echo "Hello" > greeting.txt   # Writes "Hello" to greeting.txt
wc < textfile.txt            # Counts words from textfile.txt

---

Pipes

Syntax:

command1 | command2 | command3

Description: Passes output from command1 as input to command2, and so on.

Examples:

echo "Lorem Ipsum" | wc | sed 's/ //g'   # Processes output through multiple commands

---

Redirection along with Pipes

Syntax:

command1 | command2 > output_file
command1 < input_file | command2

Description: Combines I/O redirection with pipes for more advanced command sequences.

Examples:

cat file.txt | wc > stats.txt   # Counts words in file.txt and writes to stats.txt

---

activities Command

Syntax:

activities

Description: Prints a list of all processes spawned by the shell, including command name, PID, and state.

Examples:

activities   # Displays information about currently running processes

---

ping Command

Syntax:

ping <pid> <signal_number>

Description: Sends signals to processes based on PID and signal number.

Examples:

ping 123 9    # Sends SIGKILL signal to process with PID 123
ping 456 41   # Sends signal 9 to process with PID 456

---

fg and bg Commands

Syntax:

fg <pid>
bg <pid>

Description: fg brings a background process to the foreground, and bg changes a stopped background process to running.

Examples:

fg 789    # Brings the background process with PID 789 to the foreground
bg 789    # Changes the state of process with PID 789 to running (in the background)

---

neonate Command

Syntax:

neonate -n <time_arg>

Description: Prints the Process-ID of the most recently created process every <time_arg> seconds until the key 'x' is pressed.

Examples:

neonate -n 4   # Prints the PID every 4 seconds until 'x' is pressed

---

iMan Command

Syntax:

iMan <command_name>

Description: Fetches man pages from http://man.he.net/ for the given command.

Examples:

iMan sleep            # Retrieves the man page for the 'sleep' command
iMan invalid_command  # Displays an error for a non-existing command

This detailed documentation provides users with clear information on each command's syntax, available flags, and usage examples. Include these details in your README file for user reference.