occlum/demos/fish

Run FISH script on Occlum

This demo will show Occlum's support in shell script.

Occlum now only supports FISH (the friendly interactive shell, https://github.com/fish-shell/fish-shell) for now because FISH initially use posix_spawn() to create process.

This shell script works with BusyBox (the Swiss army knife of embedded Linux, https://busybox.net/). BusyBox combines tiny versions of many common UNIX utilities into a single small executable. It provides replacements for most of the utilities you usually find in GNU fileutils, shellutils, etc.

This shell script contains executable binaries, pipe symbols and output redirection like this:

command echo "Hello-world-from-fish" | awk '$1=$1' FS="-" OFS=" " > /root/output.txt
cat /root/output.txt

which is defined in fish_script.sh. awk will replace - to space and should output result string Hello world from fish and store in /root/output.txt of Occlum SEFS and can only be read inside Occlum. echo, awk, cat here are actually symbolic files linked to busybox and in this way, we don't need to write busybox prefix. The command keyword tells FISH that echo is an external command because FISH also provides builtin echo command.

The script can be executed by Occlum directly as shown below:

occlum run /bin/fish_script.sh

As demonstrated here, Occlum supports executing any script file that begins with a shebang at its first line by invoking the interpreter program specified with the shebang.

Step 1:

Downlaod FISH and busybox and build them with Occlum tool chain:

./download_and_build.sh

Step 2:

Run command to prepare context and execute script:

./run_fish_test.sh

Or if this demo is running on non-SGX platform, use:

SGX_MODE=SIM ./run_fish_test.sh

And you should see Hello world from fish.