java - Use variable in AdminApp.update() function in WAS wsadmin -

i developing automatic deploy web app uses websphere application server (was) application server. using wsadmin features deploy file automatically. using jython version of wsadmin. able deploy using static version of command, having content argument constant. turns out content argument needs variable because file have different name every time deploy. want able use command follow:

file_name_var = /path/to/file

adminapp.update('myapp', 'file', '[-operation add -contents file_name_var -contenturi meta-inf/web.xml]')

do guys have idea of how can accomplish it? have tried few intuitive declarations variable inside update function, hasnt worked