Diff output from two programs without temporary files

Question

Say I have too programs a and b that I can run with ./a and ./b.

Is it possible to diff their outputs without first w

Answer 1

For anyone curious, this is how you perform process substitution in using the Fish shell:

Bash:

diff <(./a) <(./b)

Fish:

diff (./a | psub) (./b | psub)

Unfortunately the implementation in fish is currently deficient; fish will either hang or use a temporary file on disk. You also cannot use psub for output from your command.