Un bfaupdate.sh mas avanzado

bin/bfaupdate.sh

 #!/bin/bash
 # Robert Martin-Legene <robert@nic.ar>
+# 2019
 
+# You can start this as root or not - as long as $BFAHOME is set, it
+# should work.
+
+trap "exit 1" ERR
 if [ -z "${BFAHOME}" ]; then echo "\$BFAHOME not set. Did you source bfa/bin/env ?" >&2; exit 1; fi
 source ${BFAHOME}/bin/libbfa.sh || exit 1
 
+
+function runasownerof
+{
+    path=$1
+    precmd=
+    shift 1
+    if [ $( stat --format=%u $path ) -ne $UID ]
+    then
+        precmd="sudo -u $( stat --format=%U $path )"
+    fi
+    unset path
+    ${precmd} "$@"
+    unset precmd
+}
+
 set -x
-cd ${BFAHOME}
-sudo apt -y install libclass-accessor-perl
-git pull
-npm rebuild
+if [ "$1" = "" ]
+then
+    cd `dirname $0`
+    # Pulling may update this script itself.
+    # We pull an updated repository, including an updated version of
+    # ourself, and then we execute the updates "us"
+    # This first part of the if is static. Changes (updates to this
+    # script) goes after the 'else'
+    #
+    # To keep things neat, make sure we pull as the user owning the
+    # directory.
+    runasownerof . git pull
+    exec ./`basename $0` wealreadypulled
+else
+    cd ${BFAHOME}
+    runasownerof / apt -y install libclass-accessor-perl
+    runasownerof . npm rebuild
+fi