nodejs exec command failing with no useful error message
I'm a bit worried about the output in the console.
{ [Error: Command failed: ] killed: false, code: false, signal: undefined }
doesn't look like a proper JSON/JavaScript object, especially the [Error: Command failed: ]
part; there is at least a comma missing.
Suggestions:
Run the command from the command line and check the exit code (use
echo $?
). If the exit code is != 0, then this means the command "failed" (whatever that might mean).When the command fails, nodejs says it will put the exit code into
e.code
(which I'm missing in your output...). Find out what happened to this value.Try
if(e !== null)
instead ofif(e)
. Shouldn't make a difference, though.Instead of calling the compiler directly, call a shell script which redirects stderr/stdout to a file (or save a copy using
cc ... |& tee /tmp/cc.log
) to make sure no part of the complex setup swallows important information.
Shrikrishna Holla
Updated on June 05, 2022Comments
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Shrikrishna Holla almost 2 years
This is the code to execute
cp.exec("cc -Wall /tmp/test.c -o /tmp/test", function(e, stdout, stderr) { if (e) { var errorstr = "Compilation failed with the following error
"+ e.message.toString() client.send(errorstr) console.log(e, stdout, stderr) ee.prototype.removeAllListeners() } else if (stderr.length > 0) { client.send("Compilion finished with warnings\n"+ stderr + '\n') client.send('compiled') ee.prototype.emit('compiled') } else { client.send("Compilation successful") ee.prototype.emit('compiled') } })'client' is the argument of socket.io's callback argument. 'ee' is an instance of EventEmitter
Coming to the problem. On running the code, the callback says that the command was unsuccessful. console.log(e, stdout, stderr) is
{ [Error: Command failed: ] killed: false, code: false, signal: undefined } '' ''
/tmp/test.c is a valid C code and on checking the directory /tmp , I find that test.c is proper and the binary 'test' is being generated and on running in a shell, is properly executed. So I dont understand why it is flagging unsuccessful execution. The error object's information is unhelpful too. Would appreciate some help/explanation
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Shrikrishna Holla over 11 years(1) I did as you suggested and the exit code is 0 (2) Well, the entire error object is output here. so e.code will be false (yes, this stumped me the most) (3) Nope. No difference (4) The thing is, I don't need the stdout of this operation as mostly, stdout and stderr will be null as this is valid C code
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xiaoyi over 11 years@ShrikrishnaHolla what's the version of your node?
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Shrikrishna Holla over 11 years@xiaoyi: v0.9.6-pre (I recently cloned it from github)
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Aaron Digulla over 11 years(2) sounds like you should file a bug report with a test case. Also, since you have the source code, try to find the place which implements
exec()
and check what it really does. Maybe the documentation is simply outdated andif(e.code)
would be correct, now. -
xiaoyi over 11 years@ShrikrishnaHolla Have you tried the same code with a stable version? say 0.8.17?
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Aaron Digulla over 11 years@ShrikrishnaHolla: Your code looks correct and should work according to the documentation and all examples I've seen on the 'net so far.
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Shrikrishna Holla over 11 yearsThank you, everyone. As @AaronDigulla suggested, I will go through the source code and file a bug report, if necessary.
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Shrikrishna Holla over 11 yearsWierd. I checked out the branch v0.8.17-release because @xiaoyi said it was the most recent stable version. The bug persists! :-|
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Shrikrishna Holla over 11 yearsI have submitted an issue. The id is 4590