/usr/share/cmake-2.8/Modules/CPack.STGZ_Header.sh.in is in cmake-data 2.8.12.2-0ubuntu3.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | #!/bin/sh
# Display usage
cpack_usage()
{
  cat <<EOF
Usage: $0 [options]
Options: [defaults in brackets after descriptions]
  --help            print this message
  --prefix=dir      directory in which to install
  --include-subdir  include the @CPACK_PACKAGE_FILE_NAME@ subdirectory
  --exclude-subdir  exclude the @CPACK_PACKAGE_FILE_NAME@ subdirectory
EOF
  exit 1
}
cpack_echo_exit()
{
  echo $1
  exit 1
}
# Display version
cpack_version()
{
  echo "@CPACK_PACKAGE_NAME@ Installer Version: @CPACK_PACKAGE_VERSION@, Copyright (c) @CPACK_PACKAGE_VENDOR@"
}
# Helper function to fix windows paths.
cpack_fix_slashes ()
{
  echo "$1" | sed 's/\\/\//g'
}
interactive=TRUE
cpack_skip_license=FALSE
cpack_include_subdir=""
for a in "$@CPACK_AT_SIGN@"; do
  if echo $a | grep "^--prefix=" > /dev/null 2> /dev/null; then
    cpack_prefix_dir=`echo $a | sed "s/^--prefix=//"`
    cpack_prefix_dir=`cpack_fix_slashes "${cpack_prefix_dir}"`
  fi
  if echo $a | grep "^--help" > /dev/null 2> /dev/null; then
    cpack_usage 
  fi
  if echo $a | grep "^--version" > /dev/null 2> /dev/null; then
    cpack_version 
    exit 2
  fi
  if echo $a | grep "^--include-subdir" > /dev/null 2> /dev/null; then
    cpack_include_subdir=TRUE
  fi
  if echo $a | grep "^--exclude-subdir" > /dev/null 2> /dev/null; then
    cpack_include_subdir=FALSE
  fi
  if echo $a | grep "^--skip-license" > /dev/null 2> /dev/null; then
    cpack_skip_license=TRUE
  fi
done
if [ "x${cpack_include_subdir}x" != "xx" -o "x${cpack_skip_license}x" = "xTRUEx" ]
then
  interactive=FALSE
fi
cpack_version
echo "This is a self-extracting archive."
toplevel="`pwd`"
if [ "x${cpack_prefix_dir}x" != "xx" ]
then
  toplevel="${cpack_prefix_dir}"
fi
echo "The archive will be extracted to: ${toplevel}"
if [ "x${interactive}x" = "xTRUEx" ]
then
  echo ""
  echo "If you want to stop extracting, please press <ctrl-C>."
  if [ "x${cpack_skip_license}x" != "xTRUEx" ]
  then
    more << '____cpack__here_doc____'
@CPACK_RESOURCE_FILE_LICENSE_CONTENT@
____cpack__here_doc____
    echo
    echo "Do you accept the license? [yN]: "
    read line leftover
    case ${line} in
      y* | Y*)
        cpack_license_accepted=TRUE;;
      *)
        echo "License not accepted. Exiting ..."
        exit 1;;
    esac
  fi
  if [ "x${cpack_include_subdir}x" = "xx" ]
  then
    echo "By default the @CPACK_PACKAGE_NAME@ will be installed in:"
    echo "  \"${toplevel}/@CPACK_PACKAGE_FILE_NAME@\""
    echo "Do you want to include the subdirectory @CPACK_PACKAGE_FILE_NAME@?"
    echo "Saying no will install in: \"${toplevel}\" [Yn]: "
    read line leftover
    cpack_include_subdir=TRUE
    case ${line} in
      n* | N*)
        cpack_include_subdir=FALSE
    esac
  fi
fi
if [ "x${cpack_include_subdir}x" = "xTRUEx" ]
then
  toplevel="${toplevel}/@CPACK_PACKAGE_FILE_NAME@"
  mkdir -p "${toplevel}"
fi
echo
echo "Using target directory: ${toplevel}"
echo "Extracting, please wait..."
echo ""
# take the archive portion of this file and pipe it to tar
# the NUMERIC parameter in this command should be one more
# than the number of lines in this header file
# there are tails which don't understand the "-n" argument, e.g. on SunOS
# OTOH there are tails which complain when not using the "-n" argument (e.g. GNU)
# so at first try to tail some file to see if tail fails if used with "-n"
# if so, don't use "-n"
use_new_tail_syntax="-n"
tail $use_new_tail_syntax +1 "$0" > /dev/null 2> /dev/null || use_new_tail_syntax=""
tail $use_new_tail_syntax +###CPACK_HEADER_LENGTH### "$0" | gunzip | (cd "${toplevel}" && tar xf -) || cpack_echo_exit "Problem unpacking the @CPACK_PACKAGE_FILE_NAME@"
echo "Unpacking finished successfully"
exit 0
#-----------------------------------------------------------
#      Start of TAR.GZ file
#-----------------------------------------------------------;
 |