dd 中的“bs”选项是什么？

Question

我在互联网上发现了关于bsin a 命令是否dd bs=512 if=/home/Downloads/ubuntu.iso of=/dev/sdb代表“每秒字节数”或“块大小”的相互矛盾的信息。我在手册页中找不到任何内容，因为唯一的参考bs是：

bs=字节

一次最多读取和写入 BYTES 个字节

Answer 1

与其他 GNU Coreutils 实用程序一样，主要文档是info页面。

来自info coreutils dd invocation：

‘bs=BYTES’
     Set both input and output block sizes to BYTES.  This makes ‘dd’
     read and write BYTES per block, overriding any ‘ibs’ and ‘obs’
     settings.  In addition, if no data-transforming ‘conv’ option is
     specified, input is copied to the output as soon as it’s read, even
     if it is smaller than the block size.

各个读取、写入和转换块大小都有相应的参数：

‘ibs=BYTES’
     Set the input block size to BYTES.  This makes ‘dd’ read BYTES per
     block.  The default is 512 bytes.

‘obs=BYTES’
     Set the output block size to BYTES.  This makes ‘dd’ write BYTES
     per block.  The default is 512 bytes.

‘cbs=BYTES’
     Set the conversion block size to BYTES.  When converting
     variable-length records to fixed-length ones (‘conv=block’) or the
     reverse (‘conv=unblock’), use BYTES as the fixed record length.