How to remove all .svn directories from my application directories

No need for pipes, xargs, exec, or anything:

find . -name .svn -delete

Edit: Just kidding, evidently -delete calls unlinkat() under the hood, so it behaves like unlink or rmdir and will refuse to operate on directories containing files.

What you wrote sends a list of newline separated file names (and paths) to rm, but rm doesn't know what to do with that input. It's only expecting command line parameters.

xargs takes input, usually separated by newlines, and places them on the command line, so adding xargs makes what you had work:

find . -name .svn | xargs rm -fr

xargs is intelligent enough that it will only pass as many arguments to rm as it can accept. Thus, if you had a million files, it might run rm 1,000,000/65,000 times (if your shell could accept 65,002 arguments on the command line {65k files + 1 for rm + 1 for -fr}).

As persons have adeptly pointed out, the following also work:

find . -name .svn -exec rm -rf {} \;
find . -depth -name .svn -exec rm -fr {} \;
find . -type d -name .svn -print0|xargs -0 rm -rf

The first two -exec forms both call rm for each folder being deleted, so if you had 1,000,000 folders, rm would be invoked 1,000,000 times. This is certainly less than ideal. Newer implementations of rm allow you to conclude the command with a + indicating that rm will accept as many arguments as possible:

find . -name .svn -exec rm -rf {} +

The last find/xargs version uses print0, which makes find generate output that uses \0 as a terminator rather than a newline. Since POSIX systems allow any character but \0 in the filename, this is truly the safest way to make sure that the arguments are correctly passed to rm or the application being executed.

In addition, there's a -execdir that will execute rm from the directory in which the file was found, rather than at the base directory and a -depth that will start depth first.

Try this:

find . -name .svn -exec rm -rf '{}' \;

Before running a command like that, I often like to run this first:

find . -name .svn -exec ls '{}' \;