From: Ray Andrews <rayandrews@eastlink.ca>
To: zsh-users@zsh.org
Subject: Re: greps pipes and eval bad patterns
Date: Sun, 25 Oct 2015 20:31:17 -0700 [thread overview]
Message-ID: <562D9E85.7080006@eastlink.ca> (raw)
In-Reply-To: <151025180235.ZM30558@torch.brasslantern.com>
On 10/25/2015 06:02 PM, Bart Schaefer wrote:
> On Oct 25, 12:47pm, Ray Andrews wrote:
> }
> } test1 ()
> } {
> } gstring=" | grep \[01;34m "
> } tree --du -haC | grep -Ev "^[^\[]{$levels}\[*" "$gstring"
> } }
>
> One doesn't normally build up a pipeline that way, but if you must
What would be the better way? I'm not wedded to anything, just looking
for the
appropriate method.
> do
> so, you're on the right track with "eval" -- you just haven't applied
> enough quoting. "eval" is going to re-parse everything, so you need
> to quote everyhing to the same depth:
>
> eval 'tree --du -haC | grep -Ev "^[^\[]{$levels}\[*"' "$gstring"
>
> The single quotes (before tree and after the levels pattern) keep the
> first pipeline (and importantly the double-quotes that are around the
> grep pattern) from being interpreted until eval does so.
Enlightenment. We freeze all expansions with single quotes until eval
sorts it all out in
one go.
> The use of
> the parameter for $gstring has the same effect.
>
> You might be able to see this better if you assign everything to
> variables before eval-ing, e.g.
>
> test1 ()
> {
> gstring="| grep \[01;34m "
> glevels='| grep -Ev "^[^\[]{$levels}\[*"'
> tree="tree --du -haC"
> eval "$tree" $glevels" "$gstring"
Yeah, that's the sort of thing I'm used to doing I just didn't know how
to handle the
tricky characters. It makes nothing but sense now that I see it. So the
final product
becomes:
t ()
{
local gstring=
[ "$1" = ',f' ] && { gstring=' | grep "\[01;34m" '; shift }
integer levels=$(( ($1 + 1) * 4 ))
eval ' tree --du -haC | grep -Ev "^[^\[]{$levels}\[*" ' $gstring
du -sh .
}
... a better tree than tree.
next prev parent reply other threads:[~2015-10-26 3:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-25 19:47 Ray Andrews
2015-10-26 1:02 ` Bart Schaefer
2015-10-26 1:17 ` Kurtis Rader
2015-10-26 3:39 ` Ray Andrews
2015-10-26 3:31 ` Ray Andrews [this message]
2015-10-26 13:04 ` ZyX
2015-10-26 13:36 ` Ray Andrews
2015-10-26 14:30 ` Bart Schaefer
2015-10-26 14:49 ` Ray Andrews
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=562D9E85.7080006@eastlink.ca \
--to=rayandrews@eastlink.ca \
--cc=zsh-users@zsh.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/zsh/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).