Show error message when activate.sh/ps1 is invoked directly instead of sourced (#7731)

Helps users avoid a common mistake which is otherwise not obvious.

1 files changed, 29 insertions, 4 deletions

diff --git a/activate.sh b/activate.sh
index 894479a8b9..4986e1b297 100644
--- a/activate.sh
+++ b/activate.sh
@@ -3,10 +3,35 @@
 # You cannot run it directly.
 # To exit from the environment this creates, execute the 'deactivate' function.
 
+_RED="\033[0;31m"
 _MAGENTA="\033[0;95m"
 _YELLOW="\033[0;33m"
 _RESET="\033[0m"
 
+# This detects if a script was sourced or invoked directly
+# See https://stackoverflow.com/a/28776166/2526265
+sourced=0
+if [ -n "$ZSH_EVAL_CONTEXT" ]; then
+  case $ZSH_EVAL_CONTEXT in *:file) sourced=1;; esac
+  THIS_SCRIPT="${0:-}"
+elif [ -n "$KSH_VERSION" ]; then
+  [ "$(cd $(dirname -- $0) && pwd -P)/$(basename -- $0)" != "$(cd $(dirname -- ${.sh.file}) && pwd -P)/$(basename -- ${.sh.file})" ] && sourced=1
+  THIS_SCRIPT="${0:-}"
+elif [ -n "$BASH_VERSION" ]; then
+  (return 2>/dev/null) && sourced=1
+  THIS_SCRIPT="$BASH_SOURCE"
+else # All other shells: examine $0 for known shell binary filenames
+  # Detects `sh` and `dash`; add additional shell filenames as needed.
+  case ${0##*/} in sh|dash) sourced=1;; esac
+  THIS_SCRIPT="${0:-}"
+fi
+
+if [ $sourced -eq 0 ]; then
+    printf "${_RED}This script cannot be invoked directly.${_RESET}\n"
+    printf "${_RED}To function correctly, this script file must be sourced by calling \"source $0\".${_RESET}\n"
+    exit 1
+fi
+
 deactivate () {
 
     # reset old environment variables
@@ -38,7 +63,7 @@ deactivate () {
 # Cleanup the environment
 deactivate init
 
-DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+DIR="$( cd "$( dirname "$THIS_SCRIPT" )" && pwd )"
 _OLD_PATH="$PATH"
 # Tell dotnet where to find itself
 export DOTNET_ROOT="$DIR/.dotnet"
@@ -60,10 +85,10 @@ if [ -n "${BASH:-}" ] || [ -n "${ZSH_VERSION:-}" ] ; then
     hash -r 2>/dev/null
 fi
 
-echo "${_MAGENTA}Enabled the .NET Core environment. Execute 'deactivate' to exit.${_RESET}"
+printf "${_MAGENTA}Enabled the .NET Core environment. Execute 'deactivate' to exit.${_RESET}\n"
 
 if [ ! -f "$DOTNET_ROOT/dotnet" ]; then
-    echo "${_YELLOW}.NET Core has not been installed yet. Run $DIR/restore.sh to install it.${_RESET}"
+    printf "${_YELLOW}.NET Core has not been installed yet. Run $DIR/restore.sh to install it.${_RESET}\n"
 else
-    echo "dotnet = $DOTNET_ROOT/dotnet"
+    printf "dotnet = $DOTNET_ROOT/dotnet\n"
 fi