--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -315,12 +315,15 @@ static struct signalinfo
     {-1,	    "Unknown!", FALSE}
 };
 
+/*
+ * Write s[len] to the screen.
+ */
     void
 mch_write(s, len)
     char_u	*s;
     int		len;
 {
-    write(1, (char *)s, len);
+    ignored = (int)write(1, (char *)s, len);
     if (p_wd)		/* Unix is too fast, slow down a bit more */
 	RealWaitForChar(read_cmd_fd, p_wd, NULL);
 }
@@ -3927,9 +3930,9 @@ mch_call_shell(cmd, options)
 		 */
 		if (fd >= 0)
 		{
-		    dup(fd); /* To replace stdin  (file descriptor 0) */
-		    dup(fd); /* To replace stdout (file descriptor 1) */
-		    dup(fd); /* To replace stderr (file descriptor 2) */
+		    ignored = dup(fd); /* To replace stdin  (fd 0) */
+		    ignored = dup(fd); /* To replace stdout (fd 1) */
+		    ignored = dup(fd); /* To replace stderr (fd 2) */
 
 		    /* Don't need this now that we've duplicated it */
 		    close(fd);
@@ -3997,13 +4000,13 @@ mch_call_shell(cmd, options)
 
 		    /* set up stdin/stdout/stderr for the child */
 		    close(0);
-		    dup(pty_slave_fd);
+		    ignored = dup(pty_slave_fd);
 		    close(1);
-		    dup(pty_slave_fd);
+		    ignored = dup(pty_slave_fd);
 		    if (gui.in_use)
 		    {
 			close(2);
-			dup(pty_slave_fd);
+			ignored = dup(pty_slave_fd);
 		    }
 
 		    close(pty_slave_fd);    /* has been dupped, close it now */
@@ -4014,13 +4017,13 @@ mch_call_shell(cmd, options)
 		    /* set up stdin for the child */
 		    close(fd_toshell[1]);
 		    close(0);
-		    dup(fd_toshell[0]);
+		    ignored = dup(fd_toshell[0]);
 		    close(fd_toshell[0]);
 
 		    /* set up stdout for the child */
 		    close(fd_fromshell[0]);
 		    close(1);
-		    dup(fd_fromshell[1]);
+		    ignored = dup(fd_fromshell[1]);
 		    close(fd_fromshell[1]);
 
 # ifdef FEAT_GUI
@@ -4028,7 +4031,7 @@ mch_call_shell(cmd, options)
 		    {
 			/* set up stderr for the child */
 			close(2);
-			dup(1);
+			ignored = dup(1);
 		    }
 # endif
 		}
@@ -4159,7 +4162,8 @@ mch_call_shell(cmd, options)
 					    && (lnum !=
 						    curbuf->b_ml.ml_line_count
 						    || curbuf->b_p_eol)))
-				    write(toshell_fd, "\n", (size_t)1);
+				    ignored = write(toshell_fd, "\n",
+								   (size_t)1);
 				++lnum;
 				if (lnum > curbuf->b_op_end.lnum)
 				{