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bashcygwingreppipecut

How do you pipe input through grep to another utility?

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-

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.)

I'm using cygwin with bash.

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).

Solution

  • 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