c - read() and write() sending excess output to Vim -

i'm using read() , write() syscalls input stdin , print stdout.

from inside vim exeute command run program

:!./lowio 

the buffer array gets printed out, discarded chars didn't put array sent vim. vim interperts chars command.

#include <unistd.h> #define bufsize 3  int main() {   char low[bufsize + 1];   read(0, low, bufsize);   low[bufsize + 1] = '\0';   write(1, low, bufsize);   return 0; } 

for example, typing

abcdg 

will print abc stdin send dg vim goes , deletes cursor end of file.

what going on here?

your stdin terminal (/dev/tty) , typed abcdg<nl>. read(0,...,3) call requested 3 characters (abc) terminal device driver's buffer. remaining characters remained in buffer. when returned control vim, proceeded read stdin , remaining, buffered characters.