/usr/share/cmake-2.8/Modules/FindSWIG.cmake is in cmake-data 2.8.12.2-0ubuntu3.
This file is owned by root:root, with mode 0o644.
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 | # - Find SWIG
# This module finds an installed SWIG.  It sets the following variables:
#  SWIG_FOUND - set to true if SWIG is found
#  SWIG_DIR - the directory where swig is installed
#  SWIG_EXECUTABLE - the path to the swig executable
#  SWIG_VERSION   - the version number of the swig executable
#
# The minimum required version of SWIG can be specified using the
# standard syntax, e.g. find_package(SWIG 1.1)
#
# All information is collected from the SWIG_EXECUTABLE so the
# version to be found can be changed from the command line by
# means of setting SWIG_EXECUTABLE
#
#=============================================================================
# Copyright 2004-2009 Kitware, Inc.
# Copyright 2011 Mathieu Malaterre <mathieu.malaterre@gmail.com>
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
#  License text for the above reference.)
find_program(SWIG_EXECUTABLE NAMES swig2.0 swig)
if(SWIG_EXECUTABLE)
  execute_process(COMMAND ${SWIG_EXECUTABLE} -swiglib
    OUTPUT_VARIABLE SWIG_swiglib_output
    ERROR_VARIABLE SWIG_swiglib_error
    RESULT_VARIABLE SWIG_swiglib_result)
  if(SWIG_swiglib_result)
    if(SWIG_FIND_REQUIRED)
      message(SEND_ERROR "Command \"${SWIG_EXECUTABLE} -swiglib\" failed with output:\n${SWIG_swiglib_error}")
    else()
      message(STATUS "Command \"${SWIG_EXECUTABLE} -swiglib\" failed with output:\n${SWIG_swiglib_error}")
    endif()
  else()
    string(REGEX REPLACE "[\n\r]+" ";" SWIG_swiglib_output ${SWIG_swiglib_output})
    # force the path to be computed each time in case SWIG_EXECUTABLE has changed.
    set(SWIG_DIR SWIG_DIR-NOTFOUND)
    find_path(SWIG_DIR swig.swg PATHS ${SWIG_swiglib_output})
    if(SWIG_DIR)
      set(SWIG_USE_FILE ${CMAKE_ROOT}/Modules/UseSWIG.cmake)
      execute_process(COMMAND ${SWIG_EXECUTABLE} -version
        OUTPUT_VARIABLE SWIG_version_output
        ERROR_VARIABLE SWIG_version_output
        RESULT_VARIABLE SWIG_version_result)
      if(SWIG_version_result)
        message(SEND_ERROR "Command \"${SWIG_EXECUTABLE} -version\" failed with output:\n${SWIG_version_output}")
      else()
        string(REGEX REPLACE ".*SWIG Version[^0-9.]*\([0-9.]+\).*" "\\1"
          SWIG_version_output "${SWIG_version_output}")
        set(SWIG_VERSION ${SWIG_version_output} CACHE STRING "Swig version" FORCE)
      endif()
    endif()
  endif()
endif()
include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(SWIG  REQUIRED_VARS SWIG_EXECUTABLE SWIG_DIR
                                        VERSION_VAR SWIG_VERSION )
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