process substitution might help you avoid an explicit fifo; it should work for this example but in general handling stdin can be tricky when using process subs

process substitution might help you avoid an explicit fifo; it should work for this example but in general handling stdin can be tricky when using process substitutions. age -i <(age -d key.dat) -d input > output if you're using gnu pass to store private keys, you could do something like age -i <(pass age-key-personal) -d input > output