Question

I’m running an application (CoronaSDK Simulator) from the terminal that puts an insanely long timestamp in front of every line of output.

Is there a way to use something like sed to chop it off and instead output everything else as it comes in (i.e. without having to wait until the program ends)?

I’ve tried a couple of things, but have had no luck so far…

Here are some sample lines:

2013-02-14 12:39:49.028 Corona Simulator[40803:707] |timer created
2013-02-14 12:39:49.029 Corona Simulator[40803:707] __in deck.lua__
2013-02-14 12:39:49.030 Corona Simulator[40803:707] storyboard.roomData.layout=A1 (room.lua)

Which I want to look like this:

|timer created
__in deck.lua__
storyboard.roomData.layout=A1 (room.lua)

I have tried

coronasim ./ | sed 's/Corona Simulator//'

as a test, and

coronasim ./ | sed -e 's/^.* //'

as suggested below, and even

coronasim ./ > /dev/null

but nothing seems to change the output.

The solutions was this:

coronasim ./ 2>&1 | sed -e 's/^.*] //'

as per choroba’s suggestion below. Seems that the Corona SDK simulator sends output to stderr instead of stdout.

And for anyone else interested, created a simple bash script that runs the program in the current director in the simulator, stripping out the timestamps:

/Applications/CoronaSDK/Corona\ Simulator.app/Contents/MacOS/Corona\ Simulat
or ./ 2>&1 | sed -e 's/^.*] //'

Answer 1

Yes, sed as a stream editor should be the right tool for the job. Just redirect the output of your application to it:

myapp | sed -e 's/^.* //'

You might encounter problems, though:

1. If the application writes to a standard error rahter than standard output, you have to redirect the stream with

   myapp 2>&1 | sed -e …

2. It is possible that the application would buffer its output if it is not connected to a terminal. Unless there is a specific option to change the behaviour, you are out of luck in this case.