minishell

MindMap that works counterwise way.

Program Details

• Program Name: minishell
• Turn-in Files: Makefile, *.h, *.c

External Functions

External Functions

External Functions

#	Function	Description	Library Link
1	readline	Reads a line from the user.	Readline Library
2	rl_clear_history	Clears the entire history.	Readline Library
3	rl_on_new_line	Prepares to call readline() again.	Readline Library
4	rl_replace_line	Replaces the contents of the line buffer with a new string.	Readline Library
6	add_history	Adds a line to the command history.	Readline Library
7	printf	Prints formatted output to the standard output (stdout).	C Standard Library
8	malloc	Allocates a block of memory of specified size.	C Standard Library
9	free	Deallocates the memory previously allocated by malloc.	C Standard Library
10	write	Writes data to the specified file descriptor.	C Standard Library
11	access	Tests accessibility of a file.	C Standard Library
12	open	Opens a file or device.	C Standard Library
13	read	Reads data from a file descriptor.	C Standard Library
14	close	Closes a file descriptor.	C Standard Library
15	fork	Creates a new process by duplicating the calling process.	C Standard Library
16	wait	Waits for the child process to terminate.	C Standard Library
17	waitpid	Waits for a specific child process to terminate.	C Standard Library
18	wait3	Waits for child processes and provides status information.	C Standard Library
19	wait4	Waits for a specific child process and provides status information.	C Standard Library
20	signal	Sets a function to handle a signal.	C Standard Library
25	exit	Terminates the calling process.	C Standard Library
26	getcwd	Gets the current working directory.	C Standard Library
27	chdir	Changes the current working directory.	C Standard Library
28	stat	Gets file status.	C Standard Library
32	execve	Executes a program.	C Standard Library
33	dup	Duplicates a file descriptor.	C Standard Library
34	dup2	Duplicates a file descriptor and allows choosing a specific file descriptor number.	C Standard Library
35	pipe	Creates a pipe.	C Standard Library
39	strerror	Returns a pointer to the textual representation of the current errno value.	C Standard Library
40	getenv	Gets the value of the environment variable.	C Standard Library

Description

Write a shell that should:

• Display a prompt when waiting for a new command.
• Have a working history.
• Search and launch the right executable (based on the PATH variable or using a relative or an absolute path).
• Avoid using more than one global variable to indicate a received signal. Be careful, this global variable cannot provide any other information or data access than the number of a received signal.
• Not interpret unclosed quotes or special characters which are not required by the subject such as \ (backslash) or ; (semicolon).
• Handle ’ (single quote) which should prevent the shell from interpreting the metacharacters in the quoted sequence.
• Handle " (double quote) which should prevent the shell from interpreting the metacharacters in the quoted sequence except for $ (dollar sign).
• Implement redirections:
  • < should redirect input.

  • should redirect output.

  • << should be given a delimiter, then read the input until a line containing the delimiter is seen. However, it doesn’t have to update the history!

  • should redirect output in append mode.

• Implement pipes (| character). The output of each command in the pipeline is connected to the input of the next command via a pipe.
• Handle environment variables ($ followed by a sequence of characters) which should expand to their values.
• Handle $? which should expand to the exit status of the most recently executed foreground pipeline.
• Handle ctrl-C, ctrl-D, and ctrl-\ which should behave like in bash.
• In interactive mode:
  • ctrl-C displays a new prompt on a new line.
  • ctrl-D exits the shell.
  • ctrl-\ does nothing.
• Implement the following builtins:
  • echo with option -n
  • cd with only a relative or absolute path
  • pwd with no options
  • export with no options
  • unset with no options
  • env with no options or arguments
  • exit with no options

Note: The readline() function can cause memory leaks. You don’t have to fix them. But that doesn’t mean your own code, yes the code you wrote, can have memory leaks. You should limit yourself to the subject description. Anything that is not asked is not required. If you have any doubt about a requirement, take bash as a reference.