tail(1)tail(1)NAMEtail - deliver the last part of a file
SYNOPSIS
number] [file]
number] [file]
number] [file]
Obsolescent:
[file]
DESCRIPTION
copies the named file to the standard output beginning at a designated
place. If no file is named, standard input is used.
Command Forms
can be used in three forms as indicated above:
Copy file starting at number blocks from end or beginning of
file.
Copy file starting at number bytes from end or beginning of
file.
Copy file starting at number lines from end or
beginning of file.
with no options specified is equivalent to
Options and Command-Line Arguments
recognizes the following options and command-line argu‐
ments:
Follow option. If the input file is a regular file
or if file specifies a FIFO, do not
terminate after the last line of
the input file has been copied, but
read and copy further bytes from
the input file when they become
available enters an endless loop
wherein it sleeps for one second
then attempts to read and copy fur‐
ther records from the input file).
This is useful when monitoring text
being written to a file by another
process. If no file argument is
specified and the input is a pipe
(FIFO), the option is ignored.
number Decimal integer indicating quantity
of output to be copied, measured in
units specified by accompanying
option. If number is preceded by a
character, copy operation starts
number units from beginning of
file. If number is preceded by a
character or the option name, copy
operation starts number units from
end of file. If number is not pre‐
ceded by a or option, is assumed.
If both the option and number are
not specified, is assumed.
Copy file beginning
number 512-byte blocks from end or
beginning of file. If number is
not specified, is assumed. See
number description above.
Copy file beginning
number bytes from end or beginning
of file. If number is not speci‐
fied, is assumed. See number
description above.
Copy file beginning
number lines from end or beginning
of file. If number is not speci‐
fied, is assumed. See number
description above.
file Name of file to be copied. If not
specified, the standard input is
used.
If the option is specified, the input file can contain
arbitrary data. Otherwise, the input file should be a
text file.
Obsolescent Form
In the obsolescent form, option letters can be concate‐
nated after the number argument to select blocks, bytes,
or lines. If this syntax is used, must be the first
argument given. If number is not specified, −10 is
assumed. This version is provided for backward compati‐
bility only. The forms discussed previously are recom‐
mended for portability.
EXTERNAL INFLUENCES
Environment Variables
determines the locale for the interpretation of sequences
of bytes of text data as characters (e.g., single- versus
multibyte characters in arguments and input files).
determines the language in which messages are displayed.
If or is not specified in the environment or is set to
the empty string, the value of is used as a default for
each unspecified or empty variable. If is not specified
or is set to the empty string, a default of "C" (see
lang(5)) is used instead of
If any internationalization variable contains an invalid
setting, behaves as if all internationalization variables
are set to "C". See environ(5).
International Code Set Support
Single- and multi-byte character code sets are supported.
However, the and options can break multi-byte characters
and should be used with caution in a multi-byte locale
environment.
EXAMPLES
Print the last three lines in file to the standard out‐
put, and leave in ``follow'' mode:
Print the last 15 bytes of file followed by any lines
that are appended to after is initiated until it is
killed:
Three ways to print an entire file:
WARNINGS
Various kinds of anomalous behavior may occur with char‐
acter special files. For piped output, is limited in its
output and depends on process limits.
SEE ALSOdd(1), head(1).
STANDARDS CONFORMANCEtail(1)
