为什么我不能将输出从sed重定向到文件

问题描述

我正在尝试运行以下命令

I am trying to run the following command

./someprogram | tee /dev/tty | sed 's/^.\{2\}//' > output_file

但是当我检查该文件时，该文件始终为空白.如果我删除>从命令末尾的output_file 中，我可以看到sed的输出，而没有任何问题.

But the file is always blank when I go to check it. If I remove > output_file from the end of the command, I am able to see the output from sed without any issues.

有什么方法可以将此命令中sed的输出重定向到文件?

Is there any way that I can redirect the output from sed in this command to a file?

推荐答案

使用 -u 标志从 sed 命令中删除输出缓冲，并确保要执行的操作日志不在stderr上

Remove output-buffering from sed command using the -u flag and make sure what you want to log isn't on stderr

  load minimal amounts of data from the input files and flush the output buffers more often

最终命令:

./someprogram | tee /dev/tty | sed -u 's/^.\{2\}//' > output_file

在流中会发生这种情况(通常是程序在其整个生命周期内将输出发送到stdout).

This happens with streams (usually a program sending output to stdout during its whole lifetime).

sed / grep 和其他命令会做一些缓冲，并且您必须显式禁用它，以便在程序仍在运行时可以有输出.

sed / grep and other commands do some buffering in those cases and you have to explicitly disable it to be able to have an output while the program is still running.

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