UNIX V5, OpenBSD, Plan 9, FreeBSD, and GNU coreutils implementations of echo.c

2 - Plan 9

#include <u.h>
#include <libc.h>

void
main(int argc, char *argv[])
{
  int noNewline;
  int arg, length;
  char *output, *p;

  /* Check for -n. */
  noNewline = 0;
  if(argc > 1 && strcmp(argv[1], "-n") == 0) noNewline = 1;

  /* Figure out how big of a buffer we need. */
  length = 1;
  for(arg = 1 + noNewline; arg < argc; arg++) length += strlen(argv[arg]) + 1;

  output = malloc(length);
  if (output == 0) exits("no memory");

  /* Concatenate the remaining arguments. */
  p = result;
  for (arg = 1 + noNewline; arg < argc; arg++) {
    strcpy(p, argv[arg]);
    p += strlen(p);
    if (arg < argc - 1) *p++ = ' ';
  }

  if (!noNewline) *p++ = '\n';

  /* Write the buffer back out. */
  if (write(1, output, p - output) < 0) {
    fprint(2, "echo: write error: %r\n");
    exits("write error");
  }

  exits((char *)0);
}