Created
March 31, 2019 21:18
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bash var defined / undefined
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| #https://stackoverflow.com/a/10965292 | |
| [ -n "$var" ] && echo "var is set and not empty" | |
| [ -z "$var" ] && echo "var is unset or empty" | |
| [ "${var+x}" = "x" ] && echo "var is set" # may or may not be empty | |
| [ -n "${var+x}" ] && echo "var is set" # may or may not be empty | |
| [ -z "${var+x}" ] && echo "var is unset" | |
| [ -z "${var-x}" ] && echo "var is set and empty" |
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