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Full Discussion: Tail -f | grep > output.txt
Top Forums UNIX for Dummies Questions & Answers Tail -f | grep > output.txt Post 302928699 by Scrutinizer on Sunday 14th of December 2014 01:02:08 PM
Old 12-14-2014
This is because of output buffering. If you have GNU grep you can try:
Code:
grep --line-buffered

If not you could try:
Code:
tail -f log-file |
while IFS= read -r line
do
  case $line in
    (*"Searchstring"*) printf "%s\n" "$line"
  esac
done > output.txt

 

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IO::Async::Protocol::LineStream(3pm)			User Contributed Perl Documentation		      IO::Async::Protocol::LineStream(3pm)

NAME
"IO::Async::Protocol::LineStream" - stream-based protocols using lines of text SYNOPSIS
Most likely this class will be subclassed to implement a particular network protocol. package Net::Async::HelloWorld; use strict; use warnings; use base qw( IO::Async::Protocol::LineStream ); sub on_read_line { my $self = shift; my ( $line ) = @_; if( $line =~ m/^HELLO (.*)/ ) { my $name = $1; $self->invoke_event( on_hello => $name ); } } sub send_hello { my $self = shift; my ( $name ) = @_; $self->write_line( "HELLO $name" ); } This small example elides such details as error handling, which a real protocol implementation would be likely to contain. DESCRIPTION
EVENTS
The following events are invoked, either using subclass methods or CODE references in parameters: on_read_line $line Invoked when a new complete line of input is received. PARAMETERS
The following named parameters may be passed to "new" or "configure": on_read_line => CODE CODE reference for the "on_read_line" event. METHODS
$lineprotocol->write_line( $text ) Writes a line of text to the transport stream. The text will have the end-of-line marker appended to it; $text should not end with it. AUTHOR
Paul Evans <leonerd@leonerd.org.uk> perl v5.14.2 2012-10-24 IO::Async::Protocol::LineStream(3pm)
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