[英]How to write “command -i interval | tail” output to file
I'm using this command: 我正在使用此命令:
sar 1 | tail -n +3
which outputs the following (every 1 second, I interrupted it after few seconds): 输出以下内容(每1秒钟,我在几秒后中断它):
root@debian:/home/hyper/stats# sar 1 | tail -n +3
20:00:04 CPU %user %nice %system %iowait %steal %idle
20:00:05 all 0,25 0,00 0,50 0,00 0,00 99,25
20:00:06 all 0,50 0,00 0,25 0,00 0,00 99,25
20:00:07 all 4,79 0,00 1,01 0,00 0,00 94,21
20:00:08 all 0,75 0,00 0,75 0,75 0,00 97,74
20:00:09 all 1,26 0,00 0,76 0,00 0,00 97,98
20:00:10 all 0,75 0,00 0,50 0,00 0,00 98,74
^C
The problem is when I try to write this output to file. 问题是当我尝试将此输出写入文件时。 I tried with: 我尝试过:
sar 1 | tail -n +3 > file
But it creates an empty file. 但它会创建一个空文件。 The problem is the "sar" command that generates a "continuous output", but I don't know how to handle it. 问题是生成“连续输出”的“sar”命令,但我不知道如何处理它。
EDIT: to clarify what I want to do: "I run a command, like "top" (or "sar 1" etc.), which produces an output every X seconds. Every produced output contains an header (few lines) that I don't want. So I want to run "top" for 10 seconds and save the 10 produced outputs without their headers to a file." 编辑:澄清我想做的事情:“我运行一个命令,比如”top“(或”sar 1“等),它每X秒产生一个输出。每个产生的输出都包含一个标题(几行)我想要运行“top”10秒钟,并将10个生成的输出保存到文件中。“
sar 1 >> filename
or 要么
sar 1 | tee -a filename
You can use the tee -a
command to output to your console ( STDOUT
) and to append that output to a file at the same time. 您可以使用tee -a
命令输出到控制台( STDOUT
)并同时将该输出附加到文件。
You can append to the file without overriding it by using >>
您可以使用>>
来附加到文件而不覆盖它
Instead of using tail
, you can use a shell command list to strip out the first few lines: 您可以使用shell命令列表删除前几行,而不是使用tail
:
sar 1 | { read; read; cat; } > file.txt
I'm not sure why tail
is not working; 我不确定tail
为什么不起作用; I though perhaps you were just missing the -f
option, but that doesn't seem to produce any output either. 我可能你只是错过了-f
选项,但这似乎也没有产生任何输出。
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