tail(1)tail(1)NAMEtail - Writes a file to standard output, beginning at a specified point
SYNOPSIStail [-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The second synopsis form of this command is obsolete, and support may
be withdrawn at any time.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 stan‐
dards as follows:
tail: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
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. Over‐
rides -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 char‐
acters 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 charac‐
ters. 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 char‐
acter boundary.
EXIT STATUS
The following exit values are returned: Successful completion. An
error occurred.
EXAMPLES
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
The following environment variables affect the execution of tail: Pro‐
vides 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 vari‐
ables contain an invalid setting, the utility behaves as if none of the
variables had been defined. If set to a non-empty string value, over‐
rides 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 mulk‐
tibyte 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 process‐
ing of LC_MESSAGES.
SEE ALSO
Commands: cat(1), head(1), more(1), page(1), pg(1)
Standards: standards(5)tail(1)
