 |
Index for
Section 1 |
|
 |
Alphabetical
listing for T |
|
 |
Bottom of
page |
|
tail(1)
NAME
tail - Writes a file to standard output, beginning at a specified point
SYNOPSIS
tail [-f | -r] [-c number | -n number] [file]
tail [+number | -number] [unit] [-f | -r] [file]
The tail command writes the named file (standard input by default) to
standard output, beginning at a point you specify.
The second synopsis form of this command is obsolete, and support may be
withdrawn at any time.
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
tail: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
-c number
Displays the remainder of the file from the starting point number where
number is measured in bytes. The sign of number affects the location in
the file at which to begin the copying:
+ (plus sign)
Copying begins relative to the beginning of the file.
- (minus sign)
Copying begins relative to the end of the file.
no sign
Copying begins relative to the end of the file.
The origin for counting is 1, that is, -c +1 represents the first byte
of the file, -c -1 the last.
-f Does not end after it copies the last line of the input file if the
input file is not read from a pipe, but enters an endless loop in which
it sleeps for a second and then attempts to read and copy further
records from the input file. Thus, it can be used to monitor the
growth of a file being written by another process. Has no effect if
specified with -r.
-n number
Displays remainder of file from the starting point number where number
is measured in lines. The sign of number affects the location in the
file, measured in lines, to begin the copying:
+ (plus) sign
Copying begins relative to the beginning of the file.
- (minus) sign
Copying begins relative to the end of the file.
no sign
Copying begins relative to the end of the file.
The origin for counting is 1, that is, -n +1 represents the first line
of the file, -n -1 the last.
-r [Tru64 UNIX] Causes tail to print lines from the end of the file in
reverse order. The default for -r is to print the entire file this
way. Overrides -f.
-[number]l
-[number]b
-[number]k
-[number]c
-[number]m
Begins reading number lines (l), 512-byte blocks (b), kilobyte blocks
(k), characters (c and m) from the end of the input. The m argument
counts mulktibyte characters as single-byte characters, while c counts
characters byte-by-byte but does not break mulktibyte characters.
The default unit is l for lines. The default number is 10 for all
units.
+[number]l
+[number]b
+[number]k
+[number]c
+[number]m
Begins reading number lines (l), 512-byte blocks (b), 1-kilobyte blocks
(k), or characters (c and m) from the beginning of the input. The m
argument counts mulktibyte characters as single-byte characters, while
c counts characters byte-by-byte but does not break mulktibyte
characters.
The default unit is l for lines. The default number is 10 for all
units.
In the non-obsolescent form, if you do not specify either -c or n, -n 10 is
the default.
DESCRIPTION
If you do not specify -f, -r, -number, or +number, tail begins reading 10
lines before the end of the file. The default starting point is - (end of
input), l (lines) is the default unit, and 10 is the default number.
By specifying +, you can direct tail to read from the beginning of the
file. By specifying a number or a unit, or both, you can change the point
at which tail begins reading.
[Tru64 UNIX] The unit argument can specify lines, blocks, or characters.
The tail command can begin reading number (10 by default) units from either
the end or the beginning of the file.
[Tru64 UNIX] The block size is either 512 bytes or 1 kilobyte.
NOTES
When the input is a text file containing mulktibyte characters, use the -c
option cautiously since the output produced may not start on a character
boundary.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
EXAMPLES
1. To display the last 10 lines of a file named notes, enter:
tail notes
2. To specify how far from the end to start, enter:
tail -20 notes
This displays the last 20 lines of notes.
3. To specify how far from the beginning to start, enter:
tail +200c notes | more
This displays notes a page at a time, starting with the 200th
character from the beginning.
4. To follow the growth of a file named accounts, enter:
tail -1 -f accounts
This displays the last line of accounts. Once every second, tail
displays any lines that have been added to the file. This continues
until stopped by pressing the Interrupt key sequence.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of tail:
LANG
Provides a default value for the internationalization variables that
are unset or null. If LANG is unset or null, the corresponding value
from the default locale is used. If any of the internationalization
variables contain an invalid setting, the utility behaves as if none of
the variables had been defined.
LC_ALL
If set to a non-empty string value, overrides the values of all the
other internationalization variables.
LC_CTYPE
Determines the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
mulktibyte characters in arguments and input files).
LC_MESSAGES
Determines the locale for the format and contents of diagnostic
messages written to standard error.
NLSPATH
Determines the location of message catalogues for the processing of
LC_MESSAGES.
SEE ALSO
Commands: cat(1), head(1), more(1), page(1), pg(1)
Standards: standards(5)
|
Index for
Section 1 |
|
|
Alphabetical
listing for T |
|
 |
Top of
page |
|