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From: woodb!scsmo1!don@cs.umd.edu
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Date: 4 Mar 90 06:37:35 GMT
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To: mimsy!brl.mil!unix-wiz
Subject: Solo - logins

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Subject: Solo - logins
To: woodb!mimsy!brl.mil!unix-wiz (Unix Wizards List)
Date: Fri, 2 Mar 90 14:25:53 CST
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From: don@scsmo1.UUCP (Don Ingli)

In one of my application/logins it is necessary that there be only 1
login running at a time.  I wrote this program to echo a 'return code' to see
if the user is logging in to the system solo.

The only 2 ways I know to login is through the login shell and the su command.
Are there any other ways to 'login'?


# solo   by Don Ingli
#
# Return codes are as follows:
# 0 = a unique login, no problems
# 1 = id is already logged in, multi-user file editing problems
# 2 = tried to login via the su command from another login

id='train' 
if [ "`who am i | awk '{print $1}'`" != $id ]
then       # used su to login 
  echo 2
  exit
fi
yn=`who | awk '{print$1}' | fgrep -cx $id`
if [ "1" = "$yn" ]
then    # unique login 
 echo 0
else   # already logged in 
 echo 1
fi


-- 
 DON INGLI-United States Department of Agriculture - Soil Conservation Service
 INTERNET: scsmo1!don@uunet.uu.net    PHONEnet: 314!875!5344
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              These are my opinions. I represent myself.  
   Who do you think you are, Bjorn Nitmo?  David Letterman '90 Catch Phrase