Question

I’m generating a script like this

(echo "ssh [e-mail] echo hello" ; echo 'echo Done')

which produces

ssh [e-mail] echo hello
echo Done

If I store the generated script in a file

(echo "ssh [e-mail] echo hello" ; echo 'echo Done') > a.sh

and execute it

. ./a.sh

then it works oke and produces

Warning: No xauth data; using fake authentication data for X11 forwarding.
hello
Done

If I’m executing the script by piping these commands to bash

(echo "ssh [e-mail] echo hello" ; echo 'echo Done') | bash

The result is

Warning: No xauth data; using fake authentication data for X11 forwarding.
hello

As you can see bash did not execute the ‘echo Done’ command.

My first thought was that ssh probably produces a non zero return value probaby caused by this xauth warning. So I did this

ssh [e-mail] echo hello
echo $?

which produced

Warning: No xauth data; using fake authentication data for X11 forwarding.
hello
0

So return value is oke. Now I tried using a trap

trap "" ERR

but this also didn’t help. Pretty logical as the return value was zero anyway.

So I’m lost. Why is the ‘echo Done’ command not being executed?

UPDATE:

I noticed that when I wrap the script with brackets it works. So

( echo "(" ; echo "ssh [e-mail] echo hello" ; echo 'echo Done'; echo ")" ) | bash

produces

Warning: No xauth data; using fake authentication data for X11 forwarding.
hello
Done

Answer 1

ssh is consuming stdin, which in this case is the echo. Add -n.