An RC file is a script file containing startup instructions for an application program (or an entire operating system). These are usually a text file containing commands of the sort that might have been invoked manually once the system was running but are to be executed automatically each time the system starts up.

An RC file – also known as a configuration file – is a script file containing startup instructions for an application program (or an entire operating system). These are usually a text file containing commands of the sort that might have been invoked manually once the system was running but are to be executed automatically each time the system starts up.

Programs that support RC files include vi/vim and most shells. Some examples of RC file names would be .bashrc (for bash), .zshrc (for the Z shell), .vimrc (for vim), etc. Typically, the name of these files end in "rc"; and they often begin with "." to hide them.

"RC" stands for either "run commands" or "run control". It is a throwback to Unix's grandparent, CTSS, which had a command-script feature called "runcom" – "run commands". Early Unixes used ‘rc’ for the name of the operating system's boot script, as a tribute to CTSS runcom. This convention was then carried over to other unix programs.