You should feel free to try any of the techniques presented in this chapter. The best strategy is to test something out by typing it into the shell during your login session; then if you decide you want to make it a permanent part of your environment, add it to your .bash_profile .
A nice, painless way to add to your .bash_profile without going into a text editor makes use of the echo command and one of bash 's editing modes. If you type a customization command in and later decide to add it to your .bash_profile , you can recall it via CTRL-P or CTRL-R (in emacs-mode) or j , - , or ? (vi-mode). Let's say the line is:
PS1="\u \!> "
After you recall it, edit the line so that it is preceded by an echo command, surrounded by single quotes, and followed by an I/O redirector that (as you will see in Chapter 7 ) appends the output to ~/.bash_profile :
$ echo 'PS1="\u \!> " ' >> ~/.bash_profile
Remember that the single quotes are important because they prevent the shell from trying to interpret things like dollar signs, double quotes, and exclamation points. Also make sure that you use a double right-caret ( >> ). A single one will overwrite the file rather than appending to it.