The "= not found" error occurs when a bash-specific script is run with zsh (current default macOS shell, which gives a "%" command prompt). See: "https://www.zsh.org/mla/users/2011/msg00161.html". I think the SeaDAS 8 OCSSW_bash.env works with zsh.
The error suggests something replaced bash in your terminal with zsh. In your terminal, you can try running bash, which should change the command prompt from "%" to "$", and then "source $OCSSWROOT/OCSSW_bash.env". Some Terminal applications have options to specify which shell is used.
See: https://www.howtogeek.com/444596/how-to ... -catalina/ for more detailed explanations with screen captures.
You can edit OCSSW_bash.env to be zsh compatible. It may be useful to learn how to do this as you may encounter other bash-specific scripts.
Thanks a lot for your kindly help.
I use zsh on macOS 10.13.6 and SeaDAS 8 (replace of v7.5.3) works well now.
However a new problem comes up when I use getanc.py to catch ancillary data file: "command not found: getanc.py", it may regards to upgrade of SeaDAS but I am not clear how to solve it. Could you please help me with this new problem?