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Another newb question: how to use test for zero-length string ?

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# 1  
Old 12-15-2007
Another newb question: how to use test for zero-length string ?
Assume $x equals "".

If I try:

if test -n $x

I get the "Expression syntax" error.

It works in Linux but not in unix bash. In unix bourne I get "test: argument expected"
# 2  
Old 12-15-2007
Try putting the variable in quotes...

Code:
if test -n "$x"

# 3  
Old 12-15-2007
Or you can use square brackets instead of test:

Code:
if [ -z "$mystring" ]
then
  echo "Empty string."
fi

# 4  
Old 12-15-2007
Or:

Code:
: ${x:?inexistent or null}

# 5  
Old 12-15-2007
Ah! Thanks. I must also learn to appreciate the subtle differences between shells.
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