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Check if variable is a number

 
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# 1  
Old 03-01-2005
Check if variable is a number
If I have a variable $X, how do I check it is a number?

Many thanks.
# 2  
Old 03-01-2005
A search of the forums would have given this - there is a multiple purpose variable validation script at the end of the thread.

A simple solution would be (for positive integers)
Code:
echo $X | egrep '^[0-9]+$' >/dev/null 2>&1
if [ "$?" -eq "0" ]; then
  echo "Postive integer here...."
else
  echo "Something else...."
fi

Cheers
ZB
# 3  
Old 03-01-2005
You can also use typeset -i to define your variable as an integer. You would also have to dump the error stream to /dev/null if you attempt to assign a string to the variable (this is easily done by simply by redirection 2> /dev/null)
 
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