问题描述
当我尝试对文件进行排序并将排序后的输出本身保存时，就像这样
When I am trying to sort a file and save the sorted output in itself, like this
sort file1 > file1;
file1 的内容被完全删除了，而当我尝试用这样的tee"命令做同样的事情时
the contents of the file1 is getting erased altogether, whereas when i am trying to do the same with 'tee' command like this
sort file1 | tee file1;
它工作正常[ed:工作正常"仅适用于时间幸运的小文件，会导致大文件丢失数据或无用的进程调度]，即它正在覆盖排序的输出file1 本身并在标准输出中显示它.
it works fine [ed: "works fine" only for small files with lucky timing, will cause lost data on large ones or with unhelpful process scheduling], i.e it is overwriting the sorted output of file1 in itself and also showing it on standard output.
有人可以解释为什么第一种情况不起作用吗?
Can someone explain why the first case is not working?
推荐答案
它不起作用，因为 '>' 重定向意味着截断，并避免将 sort 的整个输出保留在内存中之前重定向到文件，bash 在运行 sort 之前截断和重定向输出.因此，file1 文件的内容将在 sort 有机会读取它之前被截断.
It doesn't work because '>' redirection implies truncation, and to avoid keeping the whole output of sort in the memory before re-directing to the file, bash truncates and redirects output before running sort. Thus, contents of the file1 file will be truncated before sort will have a chance to read it.
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