Configuration files

Configuration files are text files that help you to modify and adapt the computer system to your needs. :!: There is a convention to start the name of these files with a dot. A prominent example is the configuration file .bashrc that controls your bash environment. The dot has the effect that such files (or directories) are typically :!: hidden from the user. This should prevent an unwanted editing or deleting of these files. 'Hidden' files or directories do not show up when you list directory contents using the command ls (Fig. 1). If you add the option -a to the ls command, then also the hidden files are displayed (Fig. 2).

Figure 1: Listing directory contents using the ls command. Files whose names start with a '.' are not shown.
Figure 2: Listing directory contents using ls together with the option -a displays all files, also the hidden ones whose name start with a '.'. Note the difference to the results shown in Fig. 1.

You can modify a configuration file by opening it in a normal text editor, such as gedit, vim, or nano. Subsequent to saving your changes you have to re-load the configuration file, e.g. by typing 

source ~/.bashrc

to activate the changes in the currently active shell. If you log in the next time, the configuration file will be active.