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@ELLIOTTCABLE
Created February 10, 2015 15:55
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POSIX-compatible shell-script truthiness-checking cheat-sheet with-a hyphenated-title
[ -n "${VAR##[NFnf]*}" ] && echo '$VAR must be truthy (but will be considered falsey by default, if empty)'
[ -z "${VAR##[YTyt]*}" ] && echo '$VAR must be truthy (and will be by default, if empty)'
[ -z "${VAR##[NFnf]*}" ] && echo '$VAR must be falsey (and will be by default, if empty)'
[ -n "${VAR##[YTyt]*}" ] && echo '$VAR must be falsey (but will be considered truthy by default, if empty)'
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