cat-range-exec $RANGE /path/to/big/file command with arguments

  cat-range-exec will take a given byte range and path
  and output that range to the command given to it.
  The command will have its standard input redirected
  to the file range given to it by cat-range-exec.

  Think of it as a faster, specialized version of dd(1):

  #!/bin/ksh
  first=152284
  last=174058
  count=$(($last - $first + 1))

  # The following commands should give equivalent output:
  cat-range-exec "$first-$last" foo.log sha1sum
  dd if=foo.log bs=1 skip=$first count=$count 2>/dev/null | sha1sum
  exit 0

  Note that you do not pipe the output of cat-range-exec
  to another command, but instead just add the arguments
  needed to run that command onto the cat-range-exec
  command-line.  Thus its usage is similar to things like
  nice(1) or strace(1) or xargs(1).

  cat-range-exec can take advantage of zero-copy I/O
  facilities to minimize overhead when outputting its
  output to any given command.

  Setting the IO_FACILITY= environment variable will
  allow it to use a less-portable, but faster I/O
  facilities.

  Available values for IO_FACILITY are:
    mmap                   - Linux and Solaris
    linux_sendfile         - Linux only (uses socketpair instead of pipe)
    splice                 - Linux only (Linux >=2.6.23)
    portable               - default, any POSIX-compliant OS