use before_script in travis

.travis.yml

@@ -106,7 +106,15 @@ matrix:
       # packages:
         # - clang-5.0
 
+before_script:
+  - mkdir -p /tmp/cmake.root
+  - [[ $TRAVIS_OS_SUFFIX = 'linux' ]]; then CMAKE_PKG_SUFFIX="linux-x86_64"; else CMAKE_PKG_SUFFIX="macos10.10-universal"; fi
+  - wget -qO- "https://cmake.org/files/v3.20/cmake-3.20.5-$CMAKE_PKG_SUFFIX.tar.gz" | tar --strip-components=1 -xz -C /tmp/cmake.root
+  - [[ $TRAVIS_OS_SUFFIX = 'linux' ]]; then CMAKE_BIN_DIR="CMake.app/Contents/bin"; else CMAKE_BIN_DIR="bin"; fi
+  - export PATH=/tmp/cmake.root/$CMAKE_BIN_DIR:$PATH
+
 # Build and check this project
 script:
   - eval "${MATRIX_EVAL}"
+  - cmake --version
   - ./ci_build.sh

ci_build.sh

@@ -12,31 +12,6 @@ CPPZMQ=${PWD}/cppzmq-build
 # Travis machines have 2 cores
 JOBS=2
 
-cmake_install() {
-  local CMAKE_INSTALL_DIR=/tmp/cmake.root
-  local CMAKE_SUFFIX="none"
-
-  if [ $TRAVIS_OS_NAME = "linux" ]; then
-    CMAKE_SUFFIX="linux-x86_64"
-  elif [ $TRAVIS_OS_NAME = "osx" ]; then
-    CMAKE_SUFFIX="macos10.10-universal"
-  else
-    echo "TRAVIS_OS_NAME $TRAVIS_OS_NAME not expected"
-    exit 1
-  fi
-
-  mkdir -p $CMAKE_INSTALL_DIR
-  wget -qO- "https://cmake.org/files/v3.20/cmake-3.20.5-$CMAKE_SUFFIX.tar.gz" \
-    | tar --strip-components=1 -xz -C $CMAKE_INSTALL_DIR
-
-  if [ $TRAVIS_OS_NAME = "linux" ]; then
-    export PATH=$CMAKE_INSTALL_DIR/bin:$PATH
-  elif [ $TRAVIS_OS_NAME = "osx" ]; then
-    export PATH=$CMAKE_INSTALL_DIR/CMake.app/Contents/bin:$PATH
-  fi
-  cmake --version
-}
-
 libzmq_install() {
     curl -L https://github.com/zeromq/libzmq/archive/v"${ZMQ_VERSION}".tar.gz \
       >zeromq.tar.gz
@@ -87,8 +62,6 @@ cppzmq_demo() {
     popd
 }
 
-cmake_install
-
 if [ "${ZMQ_VERSION}" != "" ] ; then libzmq_install ; fi
 
 cppzmq_build