The STX ExecPipe library provides a convenient C++ interface to execute child programs connected via pipes. It is a front-end to the system calls fork(), pipe(), select(), and execv() and hides all the complexity of these low-level functions. It allows a program to build a sequence of connected children programs with the input and output of the pipe sequence redirected to a file, string, or file descriptor. The library also allows custom asynchronous data processing classes to be inserted into the pipe or placed at the source or sink of the sequence.
Multiple Select Dropdown List with AJAX can be used to dynamically create multiple Select lists with data from a MySQL table. When the user chooses an option from the Select list, it calls an Ajax function which accesses a PHP file, which will return another Select dropdown according to the option selected.