CODEWITHSUNDEEP
c
J. Doe
J. Doe

Reputation: 101

Getting input from user. Shell

I am writing my own simple shell and currently I'm thinking of getting input ( command ) from user.

I wrote a following prototype:

 while(1) {
        printf("gsh> ");
        fflush(stdout);
        total_len = 0;
        do {
            len = read(0, buffer,  MAX_LENGTH_OF_COMMAND-total_len -1);
            total_len+= len;
            } while( buffer[total_len-1] != '\n');
        buffer[total_len]='\0';
        parse(buffer);
    }

And this soultion seems me to be best, but I am not sure. So, I am asking for correct and recommend/advice me something.

Thanks in advance.

Upvotes: 0

Views: 64

Answers (2)

snaipeberry
snaipeberry

Reputation: 1069

A good way to create a custom prompt is using read. There is multiple ways so there is always a cleaner / better solution. But here is mine:

while ((fd = read(0, buff, BUFF_SIZE) > 0) {
    if (fd == BUFF_SIZE)
        // Command to big, handle this as you want to
    buff[fd - 1] = '\0';
    // Do what you want with your buff
}

Of course this solution has a max buffer size. You would need to wrap the read inside anoter function and use malloc to allocate the good size.

Upvotes: 0

herbert
herbert

Reputation: 111

You may rather use getchar() so you can be able to catch keys like up and down arrow (usually useful for shell history) that generate more than one character when you press it. You may also want to make your terminal as raw to get non blocking inputs.

#include <termios.h>
#include <unistd.h>
int main()
{
  struct termios oldt;
  struct termios newt;

  tcgetattr(0, &oldt);
  memcpy(&newt, &oldt, sizeof(newt));
  cfmakeraw(&newt);
  tcsetattr(0, TCSANOW, &newt);
  /* your read function ...*/

  /* before exiting restore your term */                                                                   
  tcsetattr(0, TCSANOW, &oldt);
}

Upvotes: 1

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