I did not know where else to raise an issue regarding the blog post, as getline is not there in the code on github.

The code on the blog post does not handle the case where the user inputs an EOF, wanting to exit the shell. I believe it should be:

char *lsh_read_line(void)
{
  char *line = NULL;
  ssize_t bufsize = 0;  // have getline allocate a buffer for us
  if (getline(&line, &bufsize, stdin) == -1)
    exit(EXIT_SUCCESS);
  return line;
}

Or, to be even more pedantic:

char *lsh_read_line(void)
{
  char *line = NULL;
  ssize_t bufsize = 0;  // have getline allocate a buffer for us

  if (getline(&line, &bufsize, stdin) == -1){
    if (feof(stdin)) {  
      exit(EXIT_SUCCESS);  // We recieved an EOF
    } else  {
      perror("readline");
      exit(EXIT_FAILURE);
    }
  }
  return line;
}

I really enjoyed reading this tutorial, I read it all in one go, tried to write the code, and it finally ran successfully. But I have a small problem is that I did not find any code related to the two commands ls and pwd, but I can use them when launch the program, can you explain why? Finally, thank you very much for writing this tutorial, it brought me a happy afternoon.

I believe there is a slight mistake in implementation of realloc function in the main.c at line 182. Instead of: buffer = realloc(buffer, bufsize); The code should have been: buffer = realloc(buffer, bufsize * sizeof(char));

Hi! Is this project open to contribution? He never contributes no projects in github, but he caught my attention, it would be a good challenge for me. If you want help, I'm at your disposal.

There is a small typo in src/main.c.

Should read received rather than recieved.

Semi-automated pull request generated by https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

Added simple arguments parsing code Support for ipv4 tcp client support

define FEATURE_CONNECT_TO_SERVER to add the support (-DFEATURE_CONNECT_TO_SERVER in gcc)

server example: nc -l -p 8090

In case of Error:

main.c: In function 'lsh_launch':
main.c:103:3: error: unknown type name 'pid_t'
   pid_t pid;
   ^

"In older Posix standards, pid_t was only defined in <sys/types.h>, but since Posix.1-2001 (Issue 7) it is also in <unistd.h>. However, in order to get definitions in Posix.1-2001, you must define an appropriate feature test macro before including any standard header file."

Why in child process, it exits with EXIT_FAILURE ? if (execvp(args[0], args) == -1) { perror("lsh"); } exit(EXIT_FAILURE);

I think it should be: _exit(EXIT_SUCCESS);

I modified user to use it bash shell usermod -s "binary" username it does not working, when i change back usermod -s /bin/bash username

it works

Nice little project you have here. I noticed these while reading your blog post that hit HN.

There is a bug in your getline alternative on the blog too -- you need to initialise line to NULL since POSIX says "The application shall ensure that *lineptr is a valid argument that could be passed to the free() function."

I really enjoyed testing your lsh and reading the blog post.

FYI & OFFTOPIC: I also created a simple Rust version for fun: https://gist.github.com/rubenrua/55b2ab6757b6c716f05595548784593a

I compiled your shell against musl libc and then the ">" prompt is missing.

The fix is easy enough:

diff --git a/src/main.c b/src/main.c index 39b8528..0a705eb 100644 --- a/src/main.c +++ b/src/main.c @@ -255,6 +255,7 @@ void lsh_loop(void)

do { printf("> ");

• fflush(stdout); line = lsh_read_line(); args = lsh_split_line(line); status = lsh_execute(args);

In case realloc() fails, you would lose the pointer to the memory, leaving it unable to be freed. That's why I added a temporary buffer just so it is possible to free the original memory.