tim61114/c-shell

Command Line Shell in C

This is a shell supporting basic commands, pipeline action and I/O redirection.

Things you can do

cd
ls
top
cat test.txt > another_file.txt
ls -l | sort | wc
history
!! (Execute previous command)
!(num) (Execute command number (num))

Building

To compile and run:

make
./sh

Included Files

• shell.c -- Where the magic happens/ where things get nasty
• ui.c -- Handler for input commands and prompt
• history.c -- Provide methods to query previous commands
• elist.c -- A dynamic data structure made in previous lab, used to store data

Functions and signatures

shell.c

• char *next_token(char **, const char *)
  • function to parse strings into list
• void sigint_handler(int)
  • handle SIGINT
• void destroy_cmds(struct elist *)
  • helper function to free an elist of cmd struct
• void execute_pipeline(struct elist *)
  • execvp normal/pipeline commands and perform redirection
• int execute_command(struct elist *)
  • handler for executing parsed commands
• struct elist *tokenize_command(char *)
  • parse input strings into an elist of strings
• struct elist *parse_command(struct elist *)
  • parse an elist of strings into an elist of cmd struct
• int command_handler(char *command)
  • handle different commands (execvp / history / chdir / exit )

ui.c

• char *prompt_username()
  • return current username
• char *prompt_hostname()
  • return current hostname
• char *prompt_cwd()
  • return current working directory
• void set_status(int)
  • set status code
• int prompt_status()
  • return status code
• unsigned int prompt_cmd_num()
  • return the current command number
• char *read_command()
  • return the input command from terminal or stdin

history.c

• void hist_destroy()
  • delete the history elist container
• void hist_add(const char *)
  • add a command into history elist
• void hist_print()
  • print history
• const char *hist_search_prefix(char *)
  • return the most recent command with prefix or NULL
• const char *hist_search_cnum(int)
  • return command number or NULL
• unsigned int hist_last_cnum()
  • return the command number of the most recent command

elist.c

• struct elist *elist_get_sub(struct elist *, size_t, size_t)
  • return an elist sublist of an elist between the two indexes inclusively

Execution flow

Demo Run