kind=defined
names=[],test
visibility=public

--- test(command, file1, file2)
--- [](command, file1, file2)

ファイルテスト関数testと同じ.

例:

    sh[?e, "foo"]
    sh[:e, "foo"]
    sh["e", "foo"]
    sh[:exists?, "foo"]
    sh["exists?", "foo"]

