Hacker News Reader

Comment by microtonal | Hacker News Reader

This doesn't really particularly safe to me (assuming that exec.Command allows spaces in arguments):

  cmd := exec.Command("grep", s, logName)

Since you are searching for the expression in just one log file, why not use Go's excellent regexp package?

View on HN

It started off as a class assignment where it was required to execute "grep" on whatever shell we were running the program on. That's why, instead of using the regexp package, we went for the above (somewhat shitty) approach. But, that's something I am definitely looking into changing!

You might have to work pretty hard to write a grep that's as good as grep. It pulls a lot of swift moves in the name of speed.

exec.Command doesn't run a shell; it just executes the command. So yes, it's perfectly safe to have spaces and other shell metacharacters in there. Whether or not it's efficient here is another question, of course.

So yes, it's perfectly safe to have spaces and other shell metacharacters in there.

You could (for instance) probe content of system files by passing

  -f/some/file

And matching that to the log. If you have some control over the log, you could use this to read content from system files. Of course, it's all indirect, since the file is interpreted as containing regular expressions. But it's certainly not 'perfectly safe'.

I could also read content from system files by using the advanced hacker tool "cat".

I don't see what this has to do with exec.Command.

Reply on news.ycombinator.com