Replace apache envvars with sed command -

hi guys newbie sed editor , need replace follow line on envvars file:

current line

export apache_run_user=www-data 

i need replace

export apache_run_user=admin 

i tried

sed -i "s/export apache_run_user=www-data/export apache_run_user=nbadmin/"envvars 

this not work. there space between word export , apache. can please sed? in advance.

you missing space before filename.