/bin/sh

The shell of mkfifo.com: the body is a script, with the syntax of an envelope. With -c, the script is the first word, and the body is its input.

Its form is a terminal: /bin/sh?form. Each line that you write there is a Request to /bin/sh.

Use it from the web

Its address is https://mkfifo.com//bin/sh, with two slashes. Send a POST: the body is the input, and the query gives the words, between & and with percent-encoding. The answer is the output, as the command of a shell writes it. An error gives 422 and the error.

curl --data-binary @- 'https://mkfifo.com//bin/sh' <<'EOF'
printf '%s\n' b a | sort
echo done
EOF

The answer (200):

a
b
done

Use it in an envelope

A pipe gives a value to it, as to a FIFO: $body | /bin/sh. An egress envelope can send to it, To: /bin/sh, and Reply-To gives its answer to a FIFO. These give no words: use the builtin itself for words, as in $body | jq .id.

A builtin here has no FIFO as its home: no code of totp and no sealed key of a FIFO opens in it. Each run counts in the limits of its Request.