filehandle.write(buffer[, offset[, length[, position]]])
将 buffer
写入文件。
offset
确定要写入的缓冲区部分,length
是整数,指定要写入的字节数。
position
指从文件开头数据应被写入的偏移量。
如果 typeof position !== 'number'
,则数据将写入当前位置。
参见 pwrite(2)
。
对于这种情况,请使用 fs.createWriteStream()
。
在 Linux 上,以追加模式打开文件时,位置写入不起作用。 内核会忽略位置参数,并始终将数据追加到文件末尾。
buffer
<Buffer> | <Uint8Array>offset
<integer>length
<integer>position
<integer>- Returns: <Promise>
Write buffer
to the file.
The Promise
is resolved with an object containing a bytesWritten
property
identifying the number of bytes written, and a buffer
property containing
a reference to the buffer
written.
offset
determines the part of the buffer to be written, and length
is
an integer specifying the number of bytes to write.
position
refers to the offset from the beginning of the file where this data
should be written. If typeof position !== 'number'
, the data will be written
at the current position. See pwrite(2)
.
It is unsafe to use filehandle.write()
multiple times on the same file
without waiting for the Promise
to be resolved (or rejected). For this
scenario, use fs.createWriteStream()
.
On Linux, positional writes do not work when the file is opened in append mode. The kernel ignores the position argument and always appends the data to the end of the file.