Copyright 1989 AT&T Copyright (c) 1992, X/Open Company Limited All Rights Reserved Portions Copyright (c) 2005, Sun Microsystems, Inc. All Rights Reserved
Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.
The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html.
This notice shall appear on any product containing this material.
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
/usr/bin/tail [\(+-s number [lbcr]] [file]
/usr/bin/tail [-lbcr] [file]
/usr/bin/tail [\(+- number [lbcfF]] [file]
/usr/bin/tail [-lbcfF] [file]
/usr/xpg4/bin/tail [-f | -r] [-c number | -n number] [file]
/usr/xpg4/bin/tail [\(+- number [l | b | c] [f]] [file]
/usr/xpg4/bin/tail [\(+- number [l] [f | r]] [file]
The tail utility copies the named file to the standard output beginning at a designated place. If no file is named, the standard input is used.
Copying begins at a point in the file indicated by the -cnumber, -nnumber, or \(+-number options (if +number is specified, begins at distance number from the beginning; if -number is specified, from the end of the input; if number is NULL, the value 10 is assumed). number is counted in units of lines or byte according to the -c or -n options, or lines, blocks, or bytes, according to the appended option l, b, or c. When no units are specified, counting is by lines.
The following options are supported for both /usr/bin/tail and /usr/xpg4/bin/tail. The -r and -f options are mutually exclusive. If both are specified on the command line, the -f option is ignored. -b
Units of blocks.
Units of bytes.
Follow. If the input-file is not a pipe, tail does not terminate after the last line of the input-file has been copied, but enters an endless loop, wherein it watches the file for modifications and attempts to read and copy further records from the input-file. Thus it can be used to monitor the growth of a file that is being written by some other process. If the watched file is truncated tail will begin reading records from the start of the file.
Follow named file. Operates as with -f, except that if the file is moved (e.g. if a watched log file is rotated) tail will close the original file and begin reading records from the start of the file with the specified name if and when that file is recreated.
Units of lines.
Reverse. Copies lines from the specified starting point in the file in reverse order. The default for r is to print the entire file in reverse order.
The following options are supported for /usr/xpg4/bin/tail only: -c number
The number option-argument must be a decimal integer whose sign affects the location in the file, measured in bytes, to begin the copying: +
Copying starts relative to the beginning of the file.
Copying starts relative to the end of the file.
Copying starts relative to the end of the file.
Equivalent to -cnumber, except the starting location in the file is measured in lines instead of bytes. The origin for counting is 1. That is, -n+1 represents the first line of the file, -n-1 the last.
The following operand is supported: file
A path name of an input file. If no file operands are specified, the standard input is used.
See largefile(5) for the description of the behavior of tail when encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
Example 1 Using the tail Command
The following command prints the last ten lines of the file fred, followed by any lines that are appended to fred between the time tail is initiated and killed.
example% tail -f fred
The next command prints the last 15 bytes of the file fred, followed by any lines that are appended to fred between the time tail is initiated and killed:
example% tail -15cf fred
See environ(5) for descriptions of the following environment variables that affect the execution of tail: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned: 0
Successful completion.
An error occurred.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE ATTRIBUTE VALUE |
| CSI Enabled |
| ATTRIBUTE TYPE ATTRIBUTE VALUE |
| CSI Enabled |
| Interface Stability Standard |
cat(1), head(1), more(1), pg(1), dd(1M), attributes(5), environ(5), largefile(5), standards(5)
Piped tails relative to the end of the file are stored in a buffer, and thus are limited in length. Various kinds of anomalous behavior can happen with character special files.