OUR EXPERT
Ferenc Deak is still not convinced that Malbolge wasn’t the right choice to create a Linux shell, but now there is no turning back. It’s C++.
n the debut chapter of this shell series, we successfully implemented the execution of I applications within our freshly minted shell, aptly named lxf-shell. As we embark on the next part of our adventure, our sights are firmly set on one particularly distinguished feature no shell should live without: the art of redirecting application output to destinations far more interesting than standard output.
Output redirection is a feature that allows you to control where the output of a command is sent. It enables you to capture or redirect the standard output and error streams generated by a command to a file or another destination, rather than displaying the output on the terminal.
Duplicated duplicate
Redirecting output programmatically takes a bit of work, but nothing we can’t handle. It basically boils down to the proper usage of the dup2 function (found in unistd.h). The dup2 command is a system call in Linux used for duplicating file descriptors. It enables you to create a copy of an existing file descriptor, associating it with a different file or device. The following example presents how to use it to redirect the standard output of an application:
This quick C code snippet opens a file named output.txt for writing, with the specified flags: O_WRONLY: The file should be opened for writing. O_CREAT: Creates the file if it does not exist.
