No Open Blockers

A few days ago, I was trying to get a list of all of the error codes we use in our XML-RPC exceptions. They all seemed to follow the pattern of calling into a superclass’ constructor, specifying the error code as the first parameter. For example:

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super(2754, "kickstartKeyAlreadyExists", ...

I used my normal, admittedly a bit naive, approach:

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find -name '*Exception.java' -exec grep 'super(' {} \;

In other words, find all classes that end in Exception.java and execute grep on them. The problem with this approach is the output:

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super(1025 , "notActiveSatellite" , ...
super(2301 , "invalidPackageArch", ...

It matched what I wanted it to, but it obscures the normal grep output of showing the file name. After some asking around in the #spacewalk Freenode chat room, we came up with two different ways to achieve what I wanted.

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find -name '*Exception.java' | xargs grep 'super('

I’ll leave it to the reader to check the man page for xargs for more details. As a quick summary, it’s a way of building up a command line based on an input. It’s syntax is also a ton nicer than using the -exec syntax of find.

A more to the point approach that doesn’t use find is:

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grep 'super(' -r ~/code/rhn/spacewalk/java *Exception.java

One last approach that was suggested is similar:

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grep 'super(' **/*Exception.java

The problem with the above is that it doesn’t work in bash; the original suggester likes to be weird and use zsh.

For the record, the output of the above looks as follows:

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../xmlrpc/InvalidPackageException.java:  super(2301,

That’s just a snippet that would fit on the page correctly. The important aspect is that it shows both the file name and what was matched. In most cases, that’s significantly more helpful.