I'm coding an app, which downloads and then extracts certain rar files purchased by customers. For rar unpacking I execute (with a command line) a binary file called unar from this project: http://unarchiver.c3.cx/commandline And this unar is downloaded by app as well and is placed along with rar files. According to Mac OS policies downloaded unar has only read and write permissions and no executable one. I've tried to change permission attributes with a command: chmod 777 unar. After that I see that attributes are changed to -rwxrwxrwx, but execution is still denied with an alert message: "dyld: bad external relocation length" and after it: "Trace/BPT trap: 5" So how can I set the executable permission correctly for a binary file using command line?