第一章:read/sysread/print/syswrite区别

 use strict;
 use warnings;

 #将读入的内容添加到原字符串后面
 my $buffer='START:';
 my $byts = sysread(STDIN,$buffer, , length($buffer));
 #my $byts = read(STDIN,$buffer, 10, length($buffer));
 print $buffer,"\n";

 #将字符串添加到文件后面
 open(FD, ">1.txt");
 syswrite(FD,$buffer,,);
 close(FD);
  
#sysread无缓冲/read有缓冲
#print有缓冲/syswrite无缓冲
#systead可设置追加偏移量
#syswrite可设置写入长度与开始写入的位置