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Full Discussion: using tail -f
Top Forums Shell Programming and Scripting using tail -f Post 30506 by Vishnu on Wednesday 23rd of October 2002 09:16:57 AM
Old 10-23-2002
try using

tail -f log_X | grep n >> log_Y

I'm not sure this would work...

I can add that the commands on either side of a pipe "|" are started and executed synchronously... and we know that any command like grep will finish only if it sees an EOF, which "tail -f" will not give as it is in an infinite loop looking for newly appended lines...

so...

tail -f log_X | grep n

should be working fine and giving "new" lines having "n" to stdout as and when they append to log_x...

It may be a problem with redirection, so use redirection in append mode >> and let us know!!

Cheers!
Vishnu.
 

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ZGREP(1)						    BSD General Commands Manual 						  ZGREP(1)

NAME
zgrep, zegrep, zfgrep -- print lines matching a pattern in gzip-compressed files SYNOPSIS
zgrep [grep-flags] [--] pattern [files ...] zegrep [grep-flags] [--] pattern [file ...] zfgrep [grep-flags] [--] pattern [file ...] DESCRIPTION
zgrep runs grep(1) on files or stdin, if no files argument is given, after decompressing them with zcat(1). The grep-flags and pattern arguments are passed on to grep(1). If an -e flag is found in the grep-flags, zgrep will not look for a pattern argument. zegrep calls egrep(1), while zfgrep calls fgrep(1). EXIT STATUS
In case of missing arguments or missing pattern, 1 will be returned, otherwise 0. SEE ALSO
egrep(1), fgrep(1), grep(1), gzip(1), zcat(1) AUTHORS
Thomas Klausner <wiz@NetBSD.org> BSD
December 28, 2003 BSD
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