Move crypted passwd file to /etc in build_image.

set_shared_user_password.sh

Index: set_shared_user_password.sh
diff --git a/set_shared_user_password.sh b/set_shared_user_password.sh
index 72d0ab06889e6e69313a055f18567b40941b4d5d..1ec80b5aa9bcef939bd80f605061487f73d21a2b 100755
--- a/set_shared_user_password.sh
+++ b/set_shared_user_password.sh
@@ -33,6 +33,11 @@ restart_in_chroot_if_needed "$@"
 
 FLAGS_HELP="USAGE: $0 [flags]"
 
+# TODO(petkov): This flag and setting of src/scripts/shared_user_passwd.txt can
+# go away once the transition dust settles.
+DEFINE_boolean move_to_etc ${FLAGS_FALSE} \
+  "Move src/scripts/shared_user_passwd.txt to /etc."
+
 # Parse command line
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
@@ -40,16 +45,23 @@ eval set -- "${FLAGS_ARGV}"
 # Die on any errors.
 set -e
 
+CRYPTED_PASSWD_FILE="${SCRIPTS_DIR}/shared_user_passwd.txt"
+SHARED_USER_PASSWD_FILE="/etc/shared_user_passwd.txt"
+
+if [ ${FLAGS_move_to_etc} -eq ${FLAGS_TRUE} ]; then
+  if [ -r "${CRYPTED_PASSWD_FILE}" ]; then
+    cat "${CRYPTED_PASSWD_FILE}" | sudo_clobber "${SHARED_USER_PASSWD_FILE}"
+    echo "Copied ${CRYPTED_PASSWD_FILE} to ${SHARED_USER_PASSWD_FILE}."
+  fi
+  exit 0
+fi
+
 # Get password
 read -p "Enter password for shared user account: " PASSWORD
 
 CRYPTED_PASSWD="$(echo "$PASSWORD" | openssl passwd -1 -stdin)"
 PASSWORD="gone now"
 
-CRYPTED_PASSWD_FILE="${SCRIPTS_DIR}/shared_user_passwd.txt"
 echo "${CRYPTED_PASSWD}" > "${CRYPTED_PASSWD_FILE}"
-
-SHARED_USER_PASSWD_FILE="/etc/shared_user_passwd.txt"
 echo "${CRYPTED_PASSWD}" | sudo_clobber "${SHARED_USER_PASSWD_FILE}"
-
 echo "Password set in ${CRYPTED_PASSWD_FILE} and ${SHARED_USER_PASSWD_FILE}"