Piping the output of a tail | grep command into a text file

[DeadTOm76]

My phone is occasionally having some trouble on my home network, and I'm trying to get a feel for what's happening as it goes in and out of my firewall.

I can run this command and watch the traffic in real time:

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tail -f /var/log/syslog | grep "<phone-ip>"

What I want to do is pipe that into a text file so that I can let it go for a few hours, and go over it later.

This is the command I'm running:

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tail -f /var/log/syslog | grep "<phone-ip>" > phone.log

I'm clearly doing something wrong though, because all this produces is a blank phone.log.

Any idea what I'm doing wrong here?

Thanks!

[cronoik]

You need buffering [1]:

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tail -f /var/log/syslog | grep --line-buffered "<phone-ip>" > phone.log

[1] http://mywiki.wooledge.org/BashFAQ/009

[DeadTOm76]

You need buffering [1]:

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tail -f /var/log/syslog | grep --line-buffered "<phone-ip>" > phone.log

[1] http://mywiki.wooledge.org/BashFAQ/009

Yup, that did it. Thanks!

[dilberts_left_nut]

Or you could just ‘grep phoneip /var/log/syslog’ at the end of your test period.