Having script.sh
#!/bin/sh
sh <<EOF
cat | xargs -n 1 echo captured
echo first
echo second
EOF
Running this would output
captured echo
captured first
captured echo
captured second
So that the second and the third (echo) commands were not executed but instead the cat just captures and exhausts all the upcoming commands stream and puts down to its pipe
Besides calling
echo input | script.sh
would have the very same effect.
Having the very same three commands as a plain script file script-plain.sh
#!/bin/sh
cat | xargs -n 1 echo captured
echo first
echo second
would behave differently and
echo input | script.sh
would output
input
first
second
So how to achieve having streaming pipeline e.g.
curl some-streaming-endpoint
that outputs continuously something like
echo ping 1
cat
echo ping 2
echo ping 3
....
echo ping n
the behavior of executing them as a plain script and the subject commands to capture the shell stdin it self (if any) instead of commands source one
so that how to make a script executor.sh similar to
#!/bin/sh
curl some-streaming-endpoint | sh
that with the invocation like
echo "data 1\n$data 2" | ./executor.sh
would produce the output
ping 1
data 1
data 2
ping 2
ping 3
...
ping n
P.S. without temporary piping command into a file i.e.
curl some-source > ~/tmp/source.sh
~/tmp/source.sh
since a stream might be continuous
It's not entirely clear what you intend.
If you have bash, perhaps:
#!/bin/bash
sh <(curl url)
Otherwise, you could make a fifo by hand:
#!/bin/sh
mkfifo input
curl url >input &
sh input
wait
rm input