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    The following form allows you to view linux man pages.

    Command:

    buffer

    
    
    

    SYNTAX

           buffer  [-S  size]  [-b blocks] [-s size] [-m size] [-p percentage] [-u
           microseconds] [-B] [-t] [-Z] [-i filename] [-o filename]
    
    
    

    OPTIONS

           -i filename
                Use the given file as the input file.  The default is stdin.
    
           -o filename
                Use the given file as the output file.  The default is stdout.
    
           -S size
                After every chunk of this size has been  written,  print  out  how
                much  has  been  written so far. Also prints the total throughput.
                By default this is not set.
    
           -s size
                Size in bytes of each block.  The  default  blocksize  is  10k  to
                match the normal output of the tar(1) program.
    
           -z size
                Combines the -S and -s flags.
    
           -b blocks
                Number  of  blocks  to  allocate to shared memory circular buffer.
                Defaults to the number required  to  fill  up  the  shared  memory
                requested.
    
           -m size
                Maximum size of the shared memory chunk to allocate for the circu-
                lar queue. Defaults to one megabyte.
    
           -p percentage
                Only start a write when the given percentage of the internal queue
                is  full.   A  percentage around 75 often proves best. Defaults to
                zero.
    
           -u microseconds
                After every write pause for this many microseconds.   Defaults  to
                zero.   (Surprisingly  a  small sleep, 100 usecs, after each write
                can greatly enhance throughput on some drives.)
    
           -B   Force each block written to be padded out to the blocksize.   This
                is  needed  by  some  tape  and  cartridge  drives.   Defaults  to
                unpadded.  This only affects the last block written.
    
           -t   On exiting print to stderr a brief message showing the total  num-
                ber of bytes written.
    
           -Z   If  reading/writing  directly  to  a character device (like a tape
                drive) then after each gigabyte perform an lseek to the  start  of
                the  file.   Use this flag with extreme care.  It can only be used
    
           empty.  Buffer is designed to try and keep the writer side continuously
           busy so that it can stream when writing to tape drives.  When  used  to
           write  tapes with an intervening network buffer can result in a consid-
           erable increase in throughput.
    
           The default settings for buffer are normally good enough.  If you are a
           heavy  tape user then it is worth your while trying out various differ-
           ent combinations of options.  In particular running a  buffer  at  both
           ends  of  the pipe can provide a substantial increase (see last example
           below).
    
    
    

    EXAMPLES

           $ buffer < /etc/termcap > /dev/rst8
    
           $ tar cf - . | rsh somehost 'buffer > /dev/rst8'
    
           $ dump fu - | rsh somehost 'buffer -s 16k > /dev/nrst8'
           $ tar cf - . | buffer |
              rsh somehost 'buffer -S 500K -p 75 > /dev/rst0'
    
    
    

    BUGS

           Internally, for printing purposes, buffer counts in terms of the number
           of kilobytes output.  If the blocksize you use is not a whole number of
           kilobytes then the numbers printed will be inaccurate.
    
    
    

    THANKS

           Thanks to Kevin Twidle <kpt@doc.ic.ac.uk> for a lot  of  early  sugges-
           tions  and  patches  to make it work with non-tar/dump tapes to exabyte
           drives.
    
           Thanks   to   Andi   Karrer   <karrer@bernina.ethz.ch>,   Rumi    Zahir
           <rumi@iis.ethz.ch>  and Christoph Wicki <wicki@iis.ethz.ch> for patches
           to make buffer work when trying to write single tape files  of  greater
           than 2 gigabytes.
    
    
    

    COPYRIGHT

           Copyright (C) 1990, 1991 by Lee McLoughlin.
    
    
    

    SEE ALSO

           dd(1), tar(1), rsh(1)
    
                                      14 May 1990                        BUFFER(1)
    
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