1.\" Copyright (c) 2001 2.\" Jeffrey D. Wheelhouse. All rights reserved. 3.\" 4.\" This code was originally developed by Jeff Wheelhouse (jdw@wwwi.com). 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY JEFF WHEELHOUSE ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN 18.\" NO EVENT SHALL JEFF WHEELHOUSE BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING BUT NOT 20.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 21.\" OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 22.\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 23.\" NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 24.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.\" $Id: clog.8,v 1.2 2001/10/02 04:41:21 jdw Exp $ 27.\" $DragonFly: src/usr.sbin/clog/clog.8,v 1.5 2006/05/06 17:39:29 swildner Exp $ 28.\" 29.Dd May 6, 2006 30.Dt CLOG 8 31.Os 32.Sh NAME 33.Nm clog 34.Nd "display or initialize a circular system log" 35.Sh SYNOPSIS 36.Nm 37.Op Fl f 38.Op Fl i Fl s Ar size 39.Ar logfile 40.Sh DESCRIPTION 41.Nm Clog 42displays or initializes a circular log file. 43.Pp 44The options are as follows: 45.Bl -tag -width indent 46.It Fl f 47Display the contents of the circular logfile 48.Ar logfile , 49then go into a loop waiting for 50new material to arrive. This is essentially the same as using the 51.Fl f 52option of the 53.Xr tail 1 54command on a standard syslog file. 55.It Fl i 56Initialize 57.Ar logfile 58rather than reading it. This option requires the 59.Fl s 60option. If 61.Ar logfile 62already exists, it will be truncated and recreated by this command. 63.It Fl s 64This option specifies the size in bytes of the circular logfile that should 65be created. This option requires the 66.Fl i 67option. 68.El 69.Sh ABOUT CIRCULAR LOGFILES 70The 71.Nm 72command supports circular logfiles for 73.Xr syslogd 8 . 74A circular logfile differs from a standard syslog file in that is has a fixed 75size. It does not grow, and does not need to be rotated. When 76.Xr syslogd 8 77reaches the end of a circular logfile, it simply begins again at the beginning, 78overwriting the oldest data. The circular logfile also contains information 79allowing 80.Nm 81to establish what parts of the file are valid, and in what order they should 82be displayed. 83.Pp 84Circular logfiles are primarily useful for their ability to control the amount 85of storage devoted to logfiles. This may be valuable when storage space is 86at a premium or when the consequences of running out of storage space are 87unacceptable. Circular logfiles can safely be used on a memory disk (see 88.Xr md 4 ) . 89.Pp 90Circular logfiles are also useful to catch messages that are generated rapidly 91but soon lose relevance, such as messages logged at debug priority. 92.Sh SEE ALSO 93.Xr syslog.conf 5 , 94.Xr syslogd 8 95.Sh HISTORY 96The 97.Nm 98command was written for FreeBSD 4.3 and was imported into 99.Dx 1.1 . 100