Each application that you have created is in fact a directory, and somewhere down in that directory is an executable file. To run an executable on a Unix machine, such as your Mac, a process is forked, and the new process executes the code in that file. Many executables are command line tools, and some are quite handy. This chapter shows you how to run command line tools from your Cocoa application by using the class
NSTask is an easy-to-use wrapper for the Unix functions
exec(). You give it a path to an executable and launch it. Many processes read data from standard-in and write to standard-out and standard-error. Your application can use
NSTask to attach pipes to carry data to and from the external process. ...