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IF $USER is not in this list of users, then do this

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Top Forums Shell Programming and Scripting IF $USER is not in this list of users, then do this
# 1  
Old 10-14-2009
IF $USER is not in this list of users, then do this
I need to add to a BASH script if ${USER} is not in a list of users (smitha, brownd, adamsp) then do something... what is the best shortest way to accomplish an if statement with a list like this? Also the list of users should be in the script, not an external file.

Thanks!
# 2  
Old 10-14-2009
Code:
echo 'smitha, lucyb, johnk' | grep -q ${USER} 
if [ [ $? -eq 0 ] ; then
  echo "ok"
else
  echo "not ok"
fi

# 3  
Old 10-14-2009
What does $? indicate? What is this the varible of?
# 4  
Old 10-14-2009
$? gives you the exit status of the latest command executed. In this case if this

Code:
echo 'smitha, lucyb, johnk' | grep -q ${USER}

is successfully done, then $? will be 0, else it will be 1 (or any other value between 1 and 255). Then you use that value to check if the users was found or not.
# 5  
Old 10-14-2009
Perfect, thanks so much! clever solution.

---------- Post updated at 03:54 PM ---------- Previous update was at 03:53 PM ----------

Code:
if [ [ $? -eq 0 ] ; then

Why the double brackets after if, and only on one side?
Last edited by Yogesh Sawant; 02-10-2011 at 08:17 AM.. Reason: added code tags
# 6  
Old 10-15-2009
The one sided double brackets is a typo.
You should also use the -w flag if your grep supports it.

Code:
echo 'smitha, lucyb, johnk' | grep -qw ${USER}

This way user smith is not errornously recogized as valid.
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