(coreutils.info)dirname invocation

18.2 `dirname': Strip non-directory suffix from a file name
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`dirname' prints all but the final slash-delimited component of a
string (presumably a filename).  Synopsis:

     dirname NAME

   If NAME is a single component, `dirname' prints `.' (meaning the
current directory).

   The only options are `--help' and `--version'.  Note: Common
options.

   An exit status of zero indicates success, and a nonzero value
indicates failure.