pg_enc --input-file ability to read from stdin

Hello

Is it possible to pipe stdin output to pg_end --input-file option by
using dash '-' as a placeholder for stdin?
https://www.pgpool.net/docs/latest/en/html/pg-enc.html

I tried both "echo" and "cat" and am not able to do it.

Example 1:
cat <<'EOF' | pg_enc --update-pass --key-file
/etc/pgpool-II/.pgpoolkey --config-file /etc/pgpool-II/pgpool.conf
--input-file -
username1:secretpassword1
username2:secretpassword2
EOF
trying to read key from file /etc/pgpool-II/.pgpoolkey
trying to read username:password pairs from file -
failed to open input_file "-" (No such file or directory)

Example 2:
echo '
username1:secretpassword1
username2:secretpassword2
' | pg_enc --update-pass --key-file /etc/pgpool-II/.pgpoolkey
--config-file /etc/pgpool-II/pgpool.conf --input-file -
trying to read key from file /etc/pgpool-II/.pgpoolkey
trying to read username:password pairs from file -
failed to open input_file "-" (No such file or directory)

The reason for asking about this is:
* to be able to use pg_enc in scripting setups
* to be able to provide list of usernames/passwords without having to
actually create a file
* to be able to reduce escaping when autogenerated passwords contain
special characters (by echoing literals)

P.S.
Documentation also does not mention if colon ':' needs to be escaped
(and how) when password contains colon??

Thanks
Z...