Can Somebody Explain: lm-sensors and sensors-detect...
 

Odd behavior when invoking/launching sensors-detect from within a BASH script...

Code:

---

/sbin/modprobe w83627ehf
/usr/sbin/sensors-detect < /usr/bin/yes YES

---

The sensors-detect script (Perl) seems to treat the first response as NO; all of the others are YES.

The host environment is 2.6.18-164.el5PAE (CentOS).

From the console, the behavior is nominal:

• Console
  
  Code:

  ---

  /usr/sbin/sensors-detect

  ---

  and, then, answer, manually ... you get the expected results

• Automation
  
  Code:

  ---

  /usr/sbin/sensors-detect < /usr/bin/yes YES

  ---

  produces the expected results

...but code the automated code in a BASH script and sensors-detect seems to ignore the first prompt result (treating it as a NO)!

I made a modified copy of sensors-detect (sensors-detectYES) that treats the first prompt result as 1 (true, YES, ... whatever) and all seems OK ... it's ugly but it works.

Does anybody have an explanation for what's happening?

With that syntax you are not executing the /usr/bin/yes program. You are taking the content of the /usr/bin/yes binary file and sending that to the stdin of sensors-detect. I wouldn't care to guess about how sensors-detect will parse that gibberish. Try either of these:

Batting 500
 

The former approach ("pipe")
seems to work.

The latter
just hangs ... even when executed, from the console, outside of a script.

Since the pipe technique works (and I understand it ... I swear I did try it that way, earlier ... sigh), that's what I'm going with ("Ship it!").

As to why the latter does not work, I haven't a clue: a learning experience for the future.

Thank you for your advice and help! I very much appreciate it.

That would be because I was posting in haste and made a mistake. It's just plain wrong. (It would work for programs like cat, that read either from stdin or from a filename passed as an argument. sensors-detect does not do the latter.)