你怎么管输入通过grep的另一个效用？ [英] How do you pipe input through grep to another utility?

问题描述

我使用的'尾巴-f遵​​循一个日志文件，因为它的更新;下一个I管，输出到grep只显示包含搜索术语（在这种情况下org.springframework）的线路;最后我想提出的是从管道grep的输出到第三个命令，'一刀切'：

I am using 'tail -f' to follow a log file as it's updated; next I pipe the output of that to grep to show only the lines containing a search term ("org.springframework" in this case); finally I'd like to make is piping the output from grep to a third command, 'cut':

tail -f logfile | grep org.springframework | cut -c 25-

cut命令将消除每一行的第25个字符为我的如果能得到grep的输入！（它的工作原理，如果我消除来自链的grep'预期。）

The cut command would remove the first 25 characters of each line for me if it could get the input from grep! (It works as expected if I eliminate 'grep' from the chain.)

我使用cygwin的使用bash。

I'm using cygwin with bash.

实际结果：当我添加第二管道连接到剪切命令时，结果是它挂起，因为如果它等待输入（在你不知道的情况下）

Actual results: When I add the second pipe to connect to the 'cut' command, the result is that it hangs, as if it's waiting for input (in case you were wondering).

推荐答案

在我的系统，8K左右之前，我得到任何输出被缓冲。这个序列的工作要遵循马上文件：

On my system, about 8K was buffered before I got any output. This sequence worked to follow the file immediately:

tail -f logfile | while read line ; do echo "$line"| grep 'org.springframework'|cut -c 25- ; done

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