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Full Discussion: Help grep and awk
Top Forums Shell Programming and Scripting Help grep and awk Post 302202301 by robotronic on Wednesday 4th of June 2008 01:22:11 PM
Old 06-04-2008
You don't need a while loop: "tail -f" is already an infinite loop until you manually terminate the process.

If you try:
Code:
tail -f file.log | grep "something" > output.txt

Your output file will remain empty until the grep buffer is flushed, which happens every "tot" bytes. If your grep version supports the option "--line-buffered" use it and you're done, otherwise you may need a while loop like:

Code:
tail -f file.log | while read LINE
do
   echo "$LINE" | grep "something" >> output.txt
done

Hope this helps.
 

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LEARN ABOUT DEBIAN

newslog

NEWSLOG(5)							File Formats Manual							NEWSLOG(5)

NAME

       newslog - description of Usenet log files

DESCRIPTION

       Most  log  files created by Usenet programs reside in the /var/log/news directory and have a ``.log'' extension.  Several versions are usu-
       ally kept with an additional extension such as ``.1'', ``.2'', etc. -- the higher the number, the older the log.  The  older  versions  are
       compressed.

       The scanlogs script and related utilities (see newslog(8)) are responsible for rotating and compressing these files.

       Some  log  files always have data, others only have data if there is a problem, and others are only created if a particular program is used
       or configuration parameter is set.  The innstat script (see newslog(8)) monitors the size of all log files.

       The following files will only accumulate data under the direction of control.ctl(5):
	      control.log miscctl.log newgroup.log rmgroup.log unwanted.log
       In order to create these files, the ``message'' and ``action'' fields of control.ctl should be chosen from the following table:
	      Message	  Action	 Meaning
	      all	  log=miscctl	 Log all messages by default
	      default	  log=miscctl	 Log unknown messages
	      newgroup	  doit=newgroup  Create group and log message
	      newgroup	  log=newgroup	 Log message
	      rmgroup	  doit=rmgroup	 Remove group and log message
	      rmgroup	  log=rmgroup	 Log message
	      ``other''   doit=miscctl	 log and process the message
	      ``other''   log=miscctl	 Log message
       Here, ``other'' refers to any other control message such as:
	      checkgroups ihave sendme sendsys senduuname version

       The following is a list of log files.

       control.log
	      This file maintains a count of the number of newgroup and rmgroup control messages seen for each newsgroup.  The	count  is  of  the
	      number  of  control messages with identical arguments, regardless if they were actually processed.  All control arguments, including
	      invalid ones, are counted.  This file is updated by tally.control, which is invoked by scanlogs if either the  newgroup  or  rmgroup
	      logs exist.  This file is not rotated.

       errlog This  file contains the standard output and standard error of any program spawned by innd(8).  The most common programs are the con-
	      trol-message handlers found in /usr/lib/news/control.  This file should be empty.  Scanlogs will print the entire contents  of  this
	      log file if it is non-empty.

       expire.log
	      By  default,  when  news.daily  is  going  to expire old news articles, it writes the date to this file, followed by any output from
	      expire(8) and the ending date.  All lines but the first are indented four spaces.

       miscctl.log
	      When control.ctl is configured as described above, all control messages except newgroup and rmgroup are appended	to  this  file	by
	      writelog.   There  will be a summary line describing the message and the action taken, followed by the article indented by four spa-
	      ces, and a blank line.

       newgroup.log
	      When control.ctl is configured as described above, all newgroup messages are appended to this file using the same format as for mis-
	      cctl.log.

       news   This file logs articles received by innd.  Scanlogs summarizes the rejected articles reported in this file.

       news.crit
	      All  critical  error messages issued by innd are appended to this file via syslog(3).  This log file should be empty.  Scanlogs will
	      print the entire contents of this log file if it is non-empty.  You should have the following line in your syslog.conf(5) file:
		     news.crit	/var/log/news/news.crit

       news.err
	      All major error messages issued by innd are appended to this file via syslog.  This log file should be empty.  Scanlogs  will  print
	      the entire contents of this log file if it is non-empty.	You should have the following line in your syslog.conf file:
		     news.err  /var/log/news/news.err

       news.notice
	      All  standard  error  messages  and  status  messages issued by innd are appended to this file via syslog.  Scanlogs uses the awk(1)
	      script innlog.awk to summarize this file.  You should have the following line in your syslog.conf file:
		     news.notice  /var/log/news/news.notice

       nntpsend.log
	      The nntpsend(8) programs appends all status messages to this file.

       rmgroup.log
	      When control.ctl is configured as described above, all rmgroup messages are appended to this file using the same format as for misc-
	      ctl.log.

       unwanted.log
	      This  log maintains a count of the number of articles that were rejected because they were posted to newsgroups that do not exist at
	      the local site.  This file is updated by tally.unwanted and maintained in reverse numeric order (the  most  popular  rejected  group
	      first).  This file is not rotated.

HISTORY

       Written by Landon Curt Noll <chongo@toad.com> and Rich $alz <rsalz@uunet.uu.net> for InterNetNews.  This is revision 1.6, dated 1996/09/10.

SEE ALSO

       control.ctl(5), ctlinnd(8), expire(8), innd(8), news.daily(8), nntpsend(8), newslog(8).

																	NEWSLOG(5)
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