bash read stdin after piped input

Question

I am having trouble getting bash to relinquish control of the pipe to stdin. I want to pass in the username and password to a program and then have that same program read from stdin rather than the pipe! This is what I have tried:

alias pandora='echo -e "$(cat ~/.musik/name)\n$(cat ~/.musik/pass | base64 --decode)" | pianobar'

That's in my .bashrc. First, it cat's the username/password files and then pipes that into pianobar (pandora in the terminal). The username and password get in there, however, pianobar is expecting more input. Pianobar is asking for a number (to be able to play, for example, station 12), but when I type and hit enter, nothing happens because for some reason, it isn't expecting it to come from there.

How do I get the pipe to "relinquish" control?

Note: I have also tried

echo "$(cat ~/.musik/name) $(cat ~/.musik/pass | base64 --decode) " >>> pianobar

anishsane · Accepted Answer · 2015-07-19 15:05:10Z

1

There are 2 options you can try:

Easy way: (may not work for all sorts of commands (like pianobar in this case)

alias pandora='{ echo -e "$(cat ~/.musik/name)\n$(cat ~/.musik/pass | base64 --decode)"; cat; } | pianobar'

Or with a bit cleanup & removal of UUOC:

alias pandora='{ cat ~/.musik/name; base64 --decode < ~/.musik/pass; cat; } | pianobar'

Better way: use expect script. I could have written the script, but I don't know the login prompt that your application gives.

edited Jul 19, 2015 at 15:05

answered Jul 19, 2015 at 14:48

anishsane

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11 Comments

Etan Reisner Over a year ago

I'd go with { cat; echo; cat | base64; cat; } | pianobar instead of this to avoid the unnecessary echo -e, etc.

anishsane Over a year ago

^^ Agreed. I also have same opinion. I just preferred making minimal changes to OP's script. But edited giving that solution too.

Charles Duffy Over a year ago

Using an expect script is actually more certain to work the same way real TTY input does -- if the program varies its behavior on the return value of isatty(stdin), the cat hack may not work.

anishsane Over a year ago

^^ Right. But isatty(stdin) is usually used for login stage. If Op's existing code is allowing login using redirected stdin, then quite likely (not certain), next cat would work too...

dylnmc Over a year ago

Ah, so I literally need it to relinquish control because it may need to read more than just one input. There are two problems: (1) you have to press enter (and pianobar reads key input like raw mode or something); (2) there is more than one input... so I could do while : ; do cat; done I guess.. any thoughts?

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Conlin McManus · Accepted Answer · 2017-07-07 15:38:04Z

This is the proper way to configure pianobar auto login:

 mkdir ~/.config/pianobar/ && cd ~/.config/pianobar/ && touch config

Run ^^^ in your command line then put the following in your new config file

 # User user = (Your Pandora email) password = (Your Pandora password)

https://github.com/PromyLOPh/pianobar/blob/e945578ab22912049f1e547ce7b25b01089f7590/contrib/config-example

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