Question

I am trying to make a mini shell where commands are piped to each other. At some points in the code I do:

close(1) //closing stdout

and

close(0) //closing stdin

However later on I am forking so I want my new subprocess to reset everything. So how would I:

*function_name_here*(1) //reopening stdout

and

*function_name_here*(0) //reopening stdin

Answer 1

If you’re on a UNIX-type system (and you most likely are if you’re calling fork), you can generally do one of two things.

The first is to open /dev/tty which will give you access to your terminal device (assuming the terminal device is what you want rather than the original file handle).

The second is to dup that file handle before you close it so you have a usable copy. Then, you can use dup2 to get it back. Details for Linux here, or you could also execute man dup or man dup2.