Why doesn't grep end with this regexp?

Question

I'm trying to analyze a bunch of C# files I have, with grep, to match a particular type of for-loop. Specifically, anything that looks like the following would match:

for (int i = 0; i < foo.Length; i++)
{
    foo[i] = bar[i];
}

I tried installing pcregrep after I learned grep didn't support multiline, but it's not working out. Here is my (admittedly very sloppy) regexp:

pcregrep -rlM "for (int i = 0; i < [A-Za-z]*\.Length; i++)\n[ *]\{\n[ *][A-Za-z]*\[i\] = [A-Za-z]*\[i\];\n[ *]\}"

I ran this command about 10 minutes ago, and it's still running (albeit at very low CPU usage, surprisingly). Am I doing something wrong / Is there a faster way to do this?

If you escape the parenthesis `\(`, `\)`. It will at least avoid saving items — , Aug 10 '15 at 00:06
@WashingtonGuedes Hm, I just tried that and it's still hanging. — James Ko, Aug 10 '15 at 00:09
I wrote it in a different way: `for\s*\([^)]+\)\s*{\s*\w+\[\w+\]\s*=\s*\w+\[\w+\];\s*}` — , Aug 10 '15 at 00:14
@WashingtonGuedes Thanks! I just tested out your pattern and it seems to work a lot better than mine. — James Ko, Aug 10 '15 at 02:06

score 3 · Accepted Answer · answered Aug 10 '15 at 00:15

3

pcregrep, unlike grep, doesn’t infer “use the current directory” from -r, so it’s waiting for input, which gives it the appearance of hanging. Specify the path explicitly:

pcregrep -rlM … .

answered Aug 10 '15 at 00:15

Ry-

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I probably should have realized that earlier, haha. Thanks! – James Ko Aug 10 '15 at 01:45

Why doesn't grep end with this regexp?

1 Answers1