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I want to view mplayer's normal terminal output, and also write it to a log.
That works fine when I run mplayer from the commandline, eg: 

mplayer "$HOME/gdr01.wav" 2>&1 |tee $HOME/junk.log

However, I want to launch mplayer in it's own gnome-terminal window. Neither of the following commands write to the log, althought the terminal display works. 

(gnome-terminal -e "mplayer $HOME/gdr01.wav 2>&1 |tee $HOME/junk.log" &)
 gnome-terminal -e "mplayer $HOME/gdr01.wav 2>&1 |tee $HOME/junk.log" &

What is at play here, and what is the trick to get it to work?

EDIT: The problem is that I get the terminal's mesages being written to the log (eg. an ibus warning). However, although mplayer generates thousands of lines, none are written to the log.

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3 Answers

up vote 3 down vote accepted

What's going on is that gnome-terminal's command line parsing is funky. You're running mplayer with /home/ferer/gdr01.wav, 2>&1, |tee and /home/ferer/junk.log as arguments. If you wait for the end of the audio file, you'll see error messages about these nonexistent files for a microsecond before the terminal closes.

Either figure out gnome-terminal's intricate rule. Or, what I recommend: yse the -x option instead of -e and invoke a shell explicitly.

gnome-terminal -x sh -c 'mplayer "$HOME/gdr01.wav" 2>&1 |tee $HOME/junk.log'
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@Gilles: Thanks.. This is still a fuzzy issue to me, but I haven't noticed any discernable difference in how -x vs -e work, other than the quoting syntax. However, in the last hour, I stumbled on the same shell method you've suggested, when I recalled noticing that when mplayer is run directly from the CLI, its parent is bash, but when launched as an arg to gnome-terminal its parent is gnome-terminal... so I added 'bash -c' and it worked.. I don't quite understand why.. Is it that this immediate parent layer is needed to handle the io-redirection? I suppose it is... – Peter.O Nov 25 '11 at 2:20
@ferer With -e, gnome-terminal does its own vaguely shell-like parsing of the argument (in simple cases, it splits at spaces, but that's not all it does) but does not actually invoke a shell. With -x, gnome-terminal invokes the given program with exactly the given arguments. – Gilles Nov 25 '11 at 2:28
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(a general note to readers).. Just so that I won't have to export my vars (other than known environment vars like $HOME, which are already "exported"), I've used a variant of Gilles' command; here it is: gnome-terminal -x sh -c 'mplayer "$1" 2>&1 |tee "$2"' 0 "$aud" "$log" ... The 0 is just a placeholder for what typically is $0. The two args which follow the 0 are $1 and $2 ..(the 0 can be whatever you like)... – Peter.O Nov 25 '11 at 7:29
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I would try to put exec in front of mplayer, since it is running it on a different shell.

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up vote 0 down vote 
gnome-terminal -x mplayer $HOME/gdr01.wav 2>&1 |tee $HOME/junk.log &

This command at least creates the log file.

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Your command behaves exactly the same as mine (-x vs -e). The problem is that it produces a log of the terminal's output, but not of what mplayer outputs.. It gives 1 line in the log (an ibus warning). This same message appears in the log even when not launching mplayer, eg. gnome-terminal 2>&1 |tee $HOME/junk.log & ... mplayer's output is thousands of lines long (although it appears on screen as a recurring overlaid line); it generates approximately 4-5 lines per second, but they don't end up in the log. – Peter.O Nov 25 '11 at 0:25

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