Use kill to check for process existence

Signed-off-by: Knut Ahlers <knut@ahlers.me>

bin/local-vault-auth

@@ -16,13 +16,15 @@ if ! (vault token-lookup 1>/dev/null 2>&1); then
   fi
 
   ${HOME}/bin/vault-user-token &
+  VUT=$!
+
   echo "Waiting for token to become available"
   while ! [ -f ${HOME}/.vault-token ]; do
     # Give the program a moment to get a token
     echo -n .
     sleep 0.5
 
-    if ! ( pgrep -q vault-user-token ); then
+    if ! ( kill -0 $VUT ); then
       echo "vault-user-token exitted, giving up."
       exit 1
     fi