fs.read(fd, buffer, offset, length, position, callback)
fd
<integer>buffer
<Buffer> | <TypedArray> | <DataView> 数据将写入的缓冲区。offset
<integer> 要写入数据的buffer
中的位置。length
<integer> 读取的字节数。position
<integer> | <bigint> | <null> 指定从文件中开始读取的位置。 如果position
为null
或-1
,则将从当前文件位置读取数据,并更新文件位置。 如果position
是整数,则文件位置将保持不变。callback
<Function>
从 fd
指定的文件中读取数据。
回调被赋予三个参数,(err, bytesRead, buffer)
。
如果未同时修改文件,当读取的字节数为零时,则到达文件末尾。
如果此方法作为其 util.promisify()
版本被调用,则返回具有 bytesRead
和 buffer
属性的 Object
的 promise。
fd
<integer>buffer
<Buffer> | <TypedArray> | <DataView> The buffer that the data will be written to.offset
<integer> The position inbuffer
to write the data to.length
<integer> The number of bytes to read.position
<integer> | <bigint> | <null> Specifies where to begin reading from in the file. Ifposition
isnull
or-1
, data will be read from the current file position, and the file position will be updated. Ifposition
is an integer, the file position will be unchanged.callback
<Function>
Read data from the file specified by fd
.
The callback is given the three arguments, (err, bytesRead, buffer)
.
If the file is not modified concurrently, the end-of-file is reached when the number of bytes read is zero.
If this method is invoked as its util.promisify()
ed version, it returns
a promise for an Object
with bytesRead
and buffer
properties.