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lang-bash
man test:-z STRING - the length of STRING is zero. If you want to remove all spaces in$param, use${param// /}trim()function built-in to any *nix at all? So many different hacks to achieve something so simple...[is equivalent totest. Sometimes it used to be a symlink. But[[is BASH specific and there are many differences to programtest. The reason of creating [[ was to make it easier to construct conditions. For that purpose it can't be the same as '[' ortest.