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Re: unmatched '

On 09/03/18 12:23 PM, Bart Schaefer wrote:
You really should never do this with "eval". Consider what happens if the
file name is /etc/Why you should never `rm -rf /`

(Obligatory warning:  DO NOT TRY THAT AT HOME.)
I probably have a lot of improper constructions here, I use the first thing that seems to work, and later I repent of various sins as they become apparent.  How would I best do that sort of thing?
Why are you putting stuff like that file in /etc/ in the first place?

Heck, not me!  That's stock Debian, I'd not create a directory like that on pain of damnation.  Debian should not allow it either, IMHO.

If $bar is a file name with spaces in it,

$bar will start with a list of directories as originally output by 'find', so whatever my code, it has to handle whatever 'find' might find.
Based on your description there must be a leading "|" in $grepstring.
Don't do that.

    ccolor=33      # Start with yellow, then blue, magenta, cyan.
    for file in "$@"; do
        # We colorize the already selected lines here:
        grepstring="$grepstring | GREP_COLOR='01;'"$ccolor" grep $wwild $ccase --color=always \"$file\""
        (( ccolor++ )) # Next color.

... so I'm filtering and colorizing however many arguments there are to the command, so each iteration must (?) begin with the pipe.  And the final string:

    bar=(`eval "find -H -O3  / -warn  -type d -ipath \"*$1*\"" $grepstring`)
Assuming you've carefully sanitized $grepstring to avoid gotchas like
unintentional `...` or $(...) substitutions, the closest you should
ever get to what you're doing is

baz=( `print -lr -- "${bar[@]}" | eval "$grepstring"` )

There's probably a better way to do your cascade of greps, too, such
as building a file with one pattern per line and running a single
"grep -f patternfile", but you haven't provided sufficient context.

The $grepstring itself can't have any surprises (famous last words) but the entire construction is of course suspect.  I see you're shrinking the target of eval to the minimum, that seems sensible on first principals but I can't think of a way to get the first pipe outside of $grepstring.  The thing is just to turn a string into a command because the only way I know to create flexible commands is by way of strings.

Anyway, is there no way of putting a global protection on nasty characters inside the list of directories?  I'm sure I did read about that, but there's so much to remember.

BTW I started doing this sort of cascading colorization with a very similar function I use to explore the history.  I can refine the search with as many strings as I want, and they all show up with different colors, which is even useful, not just eye candy. The final array gets fed to Sebastian's 'n_list' for selection. Quite indispensable to me.

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