Re: Parameter expansion flags question

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On May 10, 10:22am, John Cooper wrote:
}
}	delsites() {
} 	    for site in "${(f)$($SITEMGR -i)}" ; {
} 		sitepath=${${=site}[1]}
} 		[[ -n "$sitepath" ]] && $SITEMGR -r "WICurrent=$sitepath"
} 	    }
} 	}
} 
} I'm new to the zsh parameter expansion flags, but I've gathered the
} ${(f) will take the command's output a line at a time, and the ${=site}
} will then split each line into words, allowing me to grab the first word
} of each line.

Right so far.

} Is there a better (or simpler!) way to do this?

You might consider using the "read" builtin:

    $SITEMGR -i | while read -A site; {
      $SITEMGR -r "WICurrent=${site[1]}"
    }

Or:

    $SITEMGR -i | while read sitepath stuff_to_discard; {
      $SITEMGR -r "WICurrent=$sitepath"
    }

If you still want to use expansion, you can combine the expansions:

    for sitepath in ${${=${(f)"$($SITEMGR -i)"}}[1]}

Be warned, however, that ${=var} is not guaranteed to produce an array;
if any line in the $SITEMGR output has only one word in it, the result
of the above will be the first *character* of the line, not the first
*word*.  The solutions with "read" do not have this problem.

} When the command has no output, the `for' loop is still executed once
} (seemingly because the command is within double-quotes) and is the
} reason for checking that the length of $sitepath is non-zero. Is there
} a way to avoid the loop being entered when the command has no output
} and avoid the need for this check?

Change the expansion to have it discard all empty array elements by
using the ":#pattern" operator with an empty pattern:

    for sitepath in ${${=${(f)"$($SITEMGR -i)":#}}[1]}

} (btw, is there a good set of examples of using parameter expansion
} flags? The zsh guide seemed a bit sparse in this area)

Other than in the archives of this list, not that I'm aware of.  Did
you look around on zshwiki.org?