tail - Writes a file to standard output, beginning at a
specified point
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The second synopsis form of this command is obsolete, and
support may be withdrawn at any time.
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.
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: Copying begins relative to the beginning of the
file. Copying begins relative to the end of the file.
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.
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. 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:
Copying begins relative to the beginning of the
file. Copying begins relative to the end of the
file. 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.
[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. 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. 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.
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.
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.
The following exit values are returned: Successful completion.
An error occurred.
To display the last 10 lines of a file named notes, enter:
tail notes To specify how far from the end to start,
enter: tail -20 notes
This displays the last 20 lines of notes. 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. 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 [Toc] [Back] The following environment variables affect the execution
of tail: 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. If set to a non-empty
string value, overrides the values of all the other internationalization
variables. 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). Determines the
locale for the format and contents of diagnostic messages
written to standard error. Determines the location of
message catalogues for the processing of LC_MESSAGES.
Commands: cat(1), head(1), more(1), page(1), pg(1)
Standards: standards(5)
tail(1)
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