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macrumors newbie
Original poster
May 19, 2012
I am trying to run in command line tool the following code:

#import <Foundation/Foundation.h> int main(int argc, const char * argv[]) { @autoreleasepool { 

// insert code here... 
NSLog(@"Hello, World!"); 

return 0; 

and after "Build Succeeded" I am getting the following error:

error: failed to launch '/Users/rrusnac/Library/Developer/Xcode/DerivedData/5.1_Practice-gdhkgzautnruix bnobucittithbz/Build/Products/Debug/5.1 Practice ' --invalid host string: 'localhost'

It doesnt matter what code I enter, I get the same error. I cant figure out for the life of me why this is happening. I am running Xcode 4.3.2 and Lion 10.7.4.

The programs build and run with no Issues, but this error always pops up. Please help me!
Last edited by a moderator:


macrumors 6502a
Jun 25, 2012
Los Angeles
Check your /etc/hosts file and make sure it contains an entry for localhost. Default /etc/hosts should have the following entries

Code:       localhost broadcasthost
::1             localhost 
fe80::1%lo0     localhost
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