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Cpu  "runaways"

Posted on 2002-06-25
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Last Modified: 2010-04-20
Since changing from SCO-UNIX to Linux, we noticed that it is easier to produce cpu "runaways". For example, if you start a telnet session to the server, then start the shell utility "top", then ungracefully exit top (by killing the telnet session)...the "top" process continues to run but in what appears to be a race condition (uses all available cpu). I can do this (runaway) also with our propietary app, but some apps/tools do not do this , like netconfig... The "runaways" appear to be pleasent ones, just consiming cpu as it is available (look nasty, but dont seem to load down the system).
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Question by:medent
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4 Comments
 
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Expert Comment

by:ahoffmann
ID: 7108696
> .. look nasty, but dont seem to load down the system
And what is the question?

Probably your shell is configured to hangup background processes, see:
  bash: huponexit
  csh:  hup, nohup
  ksh:  nohup
  sh:   N/A :-)
  zsh:  NO_HUP
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Author Comment

by:medent
ID: 7110249
That sure sounds like the answer, but it did not work.  I tried adding shopt -s huponexit to /etc/bashrc, and verified it was really on before starting the test app (netconfig). Perhaps huponexit is broke in bash?
Additional Info:
This problem I am having does not effect the root user, regardless of the shopt settings, only regular users and when I su to root (from a regular user).
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Accepted Solution

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ahoffmann earned 300 total points
ID: 7111753
does root use bash?
do you do a  su root  or  su - root ?
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Author Comment

by:medent
ID: 7113655
The problem was caused by having "trap" statement in the .bash_profile. The trap was part of a fu-fu to get an extra password to appear when a user was detected as a dialup modem. I will seek an alternative, and post a seperate question. I learned some valuable info from your input, Thank You .
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