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I am a newbie to Ubuntu. When I execute a command in a terminal I get an error. The command is:

$ ./h_affine.ln -haraff -i img1.ppm -o img1.haraff -thres 1000

The error is:

modglue::ext_process::fork: execvp failed.

The above command is for converting an image to an array of values. Please help to sort this out. I have no idea what this error means.

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1 Answer

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There's no way to tell what the underlying problem might be from just that message. Try tracing the process, and see what happens:

strace -f ./h_affine.ln -haraff -i img1.ppm -o img1.haraff -thres 1000

Capture the output, search for "exec", and see if there are any clues about what the problem was. Basically, strace just lists all the kernel calls a program uses as it runs. This is very handy because all the things you imagine a program doing (messing with data, etc.) is just internal detail - strace captures everything it actually does.

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Thank u sir. I traced the process using the above command. But I couldn't understand what I have to do to rectify the errors. – krish Jan 30 at 10:34
Well, it looks like it's trying to execute some program, but the error doesn't show what. If strace shows a call to fork returning an error, your box may be out of resources (too many processes, or too little memory). If it shows a call to exec failing, the child program failed to start for some reason. If it doesn't show a call to exec at all, it probably means the child program couldn't be found in the first place. – Useless Jan 30 at 15:02
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