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NAME    [Toc]    [Back]

     tail - display the last part of a file

SYNOPSIS    [Toc]    [Back]

     tail [-f | -r] [-b number | -c number | -n number | -number]
[file ...]

DESCRIPTION    [Toc]    [Back]

     The  tail  utility  displays the contents of file or, by default, its standard
 input, to the standard output.

     The display begins at a byte, line, or 512-byte block  location in the input.
   Numbers having a leading plus (`+') sign are relative
to the beginning
 of the input, for example, -c +2 starts the display  at
the second
     byte  of  the  input.   Numbers having a leading minus (`-')
sign or no explicit
 sign are relative to the end of the input, for  example, -n 2 displays
 the last two lines of the input.  The default starting
location is
     -n 10, or the last 10 lines of the input.

     The options are as follows:

     -b number
             The location is number 512-byte blocks.

     -c number
             The location is number bytes.

     -n number | -number
             The location is number lines.

     -f      Do not stop when end-of-file is reached, but  rather
to wait for
             additional data to be appended to the input.  If the
file is replaced
 (i.e., the inode number changes),  tail  will
reopen the
             file  and  continue.  If the file is truncated, tail
will reset its
             position to the beginning.   This  makes  tail  more
useful for
             watching log files that may get rotated.  The -f option is ignored
 if the standard input is a pipe, but not if it
is a FIFO.

     -r       The  -r  option causes the input to be displayed in
reverse order,
             by line.   Additionally,  this  option  changes  the
meaning of the
             -b, -c, and -n options.  When the -r option is specified, these
             options  specify  the  number  of  bytes,  lines  or
512-byte blocks to
             display, instead of the bytes, lines, or blocks from
the beginning
 or end of the input from  which  to  begin  the
display.  The
             default  for  the -r option is to display all of the

     If more than a single file is specified, each file  is  preceded by a header
 consisting of the string ``==> XXX <=='' where ``XXX'' is
the name of
     the file.

     The tail utility exits 0 on success or >0 if  an  error  occurred.

EXAMPLES    [Toc]    [Back]

     To display the last 500 lines of the file foo:

           $ tail -500 foo

     Keep /var/log/messages open, displaying to the standard output anything
     appended to the file:

           $ tail -f /var/log/messages

SEE ALSO    [Toc]    [Back]

     cat(1), head(1), sed(1)

STANDARDS    [Toc]    [Back]

     The tail utility is expected to be a superset  of  the  IEEE
Std 1003.2-1992
     (``POSIX.2'')  specification.   In particular, the -b and -r
options are
     extensions to that standard.

     The historic command line syntax of  tail  is  supported  by
this implementation.
   The  only difference between this implementation and
historic versions
 of tail, once the command line syntax translation  has
been done, is
     that  the  -b, -c and -n options modify the -r option, i.e.,
-r -c 4 displays
 the last 4 characters of the last line of  the  input,
while the historic
 tail (using the historic syntax -4cr) would ignore the
-c option
     and display the last 4 lines of the input.

HISTORY    [Toc]    [Back]

     A tail command appeared in Version 7 AT&T UNIX.

OpenBSD      3.6                           June      6,      1993
[ Back ]
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