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solidsnack/isset.bash

Created November 20, 2013 08:42
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Demo of ${_+} predicate in Bash.
Raw
isset.bash
bash -c '[[ ${1+isset} ]] ; echo "#? $?" ; echo "#1 $1"' bash
#? 1
#1
bash -c '[[ ${1+isset} ]] ; echo "#? $?" ; echo "#1 $1"' bash x
#? 0
#1 x
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