I have a NAS drive from Western Digital. I can ssh into it, and when I log in, the first line that appears is:

BusyBox v1.20.2 (2014-10-30 15:28:59 CST) built-in shell (ash)

I don't like the default prompt that I get (echo $PS1 gives \u@\h \W \$). However, I can't find where this PS1 variable is set. My user is root and the only file in /home/root/ is .ash_history, and if I do a grep within the /etc/ directory, I get no results for PS1.

How can I find where the PS1 variable is set?

  • According to stackoverflow.com/a/2191917/1721265 the busybox ash is essentially dash - see linux.die.net/man/1/dash for documentation.
    – guntbert
    Mar 8, 2019 at 22:34
  • What makes you think that the PS1 setting you don't like is set somewhere, rather than being the default?
    – Ed Grimm
    Mar 8, 2019 at 23:03
  • Some systems drop root user directly to /. Check if you have /.profile for example. FHS says that root could have home in /root so also check /root/.profile - it would work if login applet was used. It doesn't look like a default bbox ash prompt, default prompt is \w \$ but it's possible that WD has modified bbox source code. Mar 9, 2019 at 2:01

1 Answer 1


Ed Grimm's comment got me thinking of an obvious workaround – I didn't know there was such a thing as a "default". If there's just a default prompt, and no PS1 variable set anywhere, well no wonder I can't find the file where PS1 is set – it doesn't exist (yet).

So, I just created a .profile file within /home/root and set the PS1 variable to the format I desire. Now, when I log in to the NAS, this .profile file is automatically read and the prompt displays just how I want.

  • This is definitely an answer!
    – guntbert
    Mar 12, 2019 at 21:22
  • My .profile file was working just fine for me, until I ssh'd into my NAS today - the file had disappeared. I can only assume that a recent firmware update (which the NAS does automatically) deleted the file. Just something to keep in my mind in case anyone else encounters a similar situation to mine.
    – osullic
    Apr 24, 2019 at 8:58
  • 1
    My /root/.profile is not executed when I start 'ash'. Any hints anyone?
    – Ingo Baab
    May 21, 2022 at 3:39

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