tail



TAIL(1)                     General Commands Manual                    TAIL(1)


NAME

     tail - display the last part of a file


SYNOPSIS

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


DESCRIPTION

     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.

     -f      Do not stop when end-of-file is reached; instead, 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 there are no file arguments and the standard input is
             a pipe or a FIFO.

     -n number | -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 one file is specified, tail precedes the output of each file
     with the following, in order to distinguish files:

           ==> file <==


EXIT STATUS

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


EXAMPLES

     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

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


STANDARDS

     The tail utility is compliant with the IEEE Std 1003.1-2008 (``POSIX.1'')
     specification.

     The flags [-br] are extensions to that specification.

     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

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

OpenBSD 5.9                    October 25, 2015                    OpenBSD 5.9

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