Adding LCG to thisREST.sh if LCG environment is identified

cmake/thisREST.cmake

@@ -1,5 +1,26 @@
 # Write thisREST.[c]sh to INSTALL directory
 
+# Checking if we are using CVMFS LCG GCC11 environment
+set(lcg_found FALSE)
+
+# Check if the CMAKE_COMMAND contains both "cvmfs", "lcg" and "x86_64-el9-gcc11"
+string(FIND "${CMAKE_COMMAND}" "cvmfs" cvmfs_pos)
+string(FIND "${CMAKE_COMMAND}" "lcg" lcg_pos)
+string(FIND "${CMAKE_COMMAND}" "x86_64-el9-gcc11" gcc_pos)
+
+if (lcg_pos GREATER -1
+    AND cvmfs_pos GREATER -1
+    AND gcc_pos GREATER -1)
+    set(lcg_found TRUE)
+endif ()
+
+set(loadLCG "")
+if (lcg_found)
+    set(loadLCG
+        "\# We load LCG_104 environment.\nsource /cvmfs/sft.cern.ch/lcg/views/LCG_104/x86_64-el9-gcc11-opt/setup.sh\n\n"
+    )
+endif ()
+
 # We identify the thisroot.sh script for the corresponding ROOT version
 execute_process(
     COMMAND root-config --prefix
@@ -97,6 +118,8 @@ file( WRITE \${CMAKE_INSTALL_PREFIX}/thisREST.sh
 
 \"\#!/bin/bash
 
+${loadLCG}
+
 \# check active shell by checking for existence of _VERSION variable
 if [[ -n \\\"\\\${BASH_VERSION}\\\" ]]; then
     thisdir=\\\$(cd \\\$(dirname \\\${BASH_ARGV[0]}); pwd)