Setting Custom Prompts

O'Reilly's UNIX Power Tools, 3rd Ed inspired me to change the default prompts on my FreeBSD systems. My user account uses bash, so I made the following entry in ~/.profile to ensure my prompt shows my username, system name, and present working directory when I log in. The single straight quotes ensure that $PWD is substituted every time I change directories. If I had used double straight quotes, then $PWD would be fixed at whatever my current directory was when the shell was started. Single straight quotes helps us use "dynamic substitution." Using the back ticks sets the value of the system name.

PS1='$USER@`hostname -s`:$PWD '

Here's the result:

richard@orr:/home/richard$

Changing .profile affects prompts seen when logging in to the terminal and remotely via SSH. This entry in ~/.profile doesn't influence the prompt seen by terminals started within X, as they are not "interactive" shells. (I still haven't figured that one out.) To ensure terminals in X share the same prompt, I made the same entry in the .bashrc file.

For tcsh, the default shell for root on FreeBSD (csh and tcsh are the same binary), I made this entry in /root/.cshrc after the 'set mail' line:

set prompt = "%n@%m:%/# "

Tcsh doesn't support much dynamic substition, but a read of the tcsh man page showed several variables built into the shell provide what I need. %n is the username. %m is the hostname up to the first period. %/ is the present working directory. All together the result looks good:

root@orr:/root#

Keep in mind these prompts start to take up valuable terminal space. You can eliminate the %n in the csh prompt as the # shows you are root. If you primarily deal with a single user account, or don't care to know your login name, similarly eliminate the $USER@ from the bash prompt.

I will review UNIX Power Tools when done reading it, but I can already recommend buying it.

Popular posts from this blog

Zeek in Action Videos

Image
This is a quick note to point blog readers to my Zeek in Action YouTube video series for the Zeek network security monitoring project .  Each video addresses a topic that I think might be of interest to people trying to understand their network using Zeek and adjacent tools and approaches, like Suricata, Wireshark, and so on.  I am especially pleased with Video 6 on monitoring wireless networks . It took me several weeks to research material for this video. I had to buy new hardware and experiment with a Linux distro that I had not used before -- Parrot .  Please like and subscribe, and let me know if there is a topic you think might make a good video.
Read more

MITRE ATT&CK Tactics Are Not Tactics

Image
Just what are "tactics"? Introduction MITRE ATT&CK  is a great resource, but something about it has bothered me since I first heard about it several years ago. It's a minor point, but I wanted to document it in case it confuses anyone else. The MITRE ATT&CK Design and Philosophy document from March 2020 says the following: At a high-level, ATT&CK is a behavioral model that consists of the following core components: • Tactics, denoting short-term, tactical adversary goals during an attack; • Techniques, describing the means by which adversaries achieve tactical goals; • Sub-techniques, describing more specific means by which adversaries achieve tactical goals at a lower level than techniques; and • Documented adversary usage of techniques, their procedures, and other metadata. My concern is with MITRE's definition of "tactics" as "short-term, tactical adversary goals during an attack," which is oddly recursive. The key word in the tacti
Read more

New Book! The Best of TaoSecurity Blog, Volume 4

Image
  I've completed the TaoSecurity Blog book series . The new book is  The Best of TaoSecurity Blog, Volume 4: Beyond the Blog with Articles, Testimony, and Scholarship .  It's available now for Kindle , and I'm working on the print edition.  I'm running a 50% off promo on Volumes 1-3 on Kindle through midnight 20 April. Take advantage before the prices go back up. I described the new title thus: Go beyond TaoSecurity Blog with this new volume from author Richard Bejtlich. In the first three volumes of the series, Mr. Bejtlich selected and republished the very best entries from 18 years of writing and over 18 million blog views, along with commentaries and additional material.  In this title, Mr. Bejtlich collects material that has not been published elsewhere, including articles that are no longer available or are stored in assorted digital or physical archives. Volume 4 offers early white papers that Mr. Bejtlich wrote as a network defender, either for technical or pol
Read more