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TAIL(1)                     NetBSD Reference Manual                    TAIL(1)


NAME

     tail - display the last part of a file


SYNOPSIS

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


DESCRIPTION

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

     The display begins at a byte, line or 512-byte block location in the in-
     put.  Numbers having a leading plus (``+'') sign are relative to the be-
     ginning 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 loca-
     tion 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.

     -f      The -f option causes tail to not stop when end of file is
             reached, but rather to wait for additional data to be appended to
             the input.  The -f option is ignored if the standard input is a
             pipe, but not if it is a FIFO.

     -n number
             The location is number lines.

     -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 input.

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

     The tail utility exits 0 on success, and >0 if an error occurs.


SEE ALSO

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


STANDARDS

     The tail utility is expected to be a superset of the IEEE Std1003.2-1992
     (``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 implementa-
     tion.  The only difference between this implementation and historic ver-
     sions 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

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

4th Berkeley Distribution        June 6, 1993                                2