From: "John Cooper" <john.cooper@eu.citrix.com>
To: "Bart Schaefer" <schaefer@brasslantern.com>, <zsh-users@sunsite.dk>
Subject: RE: Parameter expansion flags question
Date: Thu, 11 May 2006 10:59:29 +0100 [thread overview]
Message-ID: <DD74FBB8EE28D441903D56487861CD9D09717293@lonpexch01.citrite.net> (raw)
Bart,
Thanks for the detailed reply - it seems using "read" is the most
straightforward approach. However, in the interests of learning more
about expansions, I've been trying your suggestions and they don't seem
to work as expected.
$ $SITEMGR -i
1:/Citrix/Pres WI http://RA.eng.citrite.net/Citrix/Pres
4.5.5.1159 c:\inetpub\wwwroot\Citrix\Pres
1:/Citrix/Pres2 WI http://RA.eng.citrite.net/Citrix/Pres2
4.5.5.1159 c:\inetpub\wwwroot\Citrix\Pres2
(not sure if Outlook will wrap the above, but the output is actually 2
lines, each starting "1:/Citrix")
My original function correctly finds the first word of both lines:
$ type delsites2
delsites2 () {
for site in "${(f)$($SITEMGR -i)}"
do
sitepath=${${=site}[1]}
echo "sitepath is $sitepath"
done
}
$ delsites2
sitepath is 1:/Citrix/Pres
sitepath is 1:/Citrix/Pres2
$
However, when the expansions are combined, it only finds the first word
of the first line:
$ type delsites3
delsites3 () {
for sitepath in ${${=${(f)"$($SITEMGR -i)"}}[1]}
do
echo "sitepath is $sitepath"
done
}
$ delsites3
sitepath is 1:/Citrix/Pres
$
If I add the ":#pattern" operator to the original function, the "for"
loop is still executed once in the case where $SITEMGR produces no
output:
$ type delsites4
delsites4 () {
for site in "${(f)$($SITEMGR -i):#}"
do
sitepath=${${=site}[1]}
echo sitepath is "$sitepath"
done
}
$ delsites
$ $SITEMGR -i
$
$ delsites4
sitepath is
$
One final thing - when I entered the "read" example into the shell as
stated I got syntax errors. These were resolved by using "do" and "done"
instead of braces - is this to be expected?
$ $SITEMGR -i
1:/Citrix/Pres WI http://RA.eng.citrite.net/Citrix/Pres
4.5.5.1159 c:\inetpub\wwwroot\Citrix\Pres
$ $SITEMGR -i | while read -A site; {
pipe while cursh> echo $site
pipe while cursh> }
pipe while> }
zsh: parse error near `}'
$
$ $SITEMGR -i | while read -A site; do
pipe while> echo $site
pipe while> done
1:/Citrix/Pres WI http://RA.eng.citrite.net/Citrix/Pres 4.5.5.1159
c:inetpubwwwrootCitrixPres
$
I'm using zsh 4.2.6 on cygwin/WinXP.
--- John
-----Original Message-----
From: Bart Schaefer [mailto:schaefer@brasslantern.com]
Sent: 10 May 2006 18:28
To: zsh-users@sunsite.dk
Subject: Re: Parameter expansion flags question
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?
next reply other threads:[~2006-05-11 10:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-11 9:59 John Cooper [this message]
2006-05-11 16:38 ` Bart Schaefer
-- strict thread matches above, loose matches on Subject: below --
2006-05-15 9:01 John Cooper
2006-05-12 11:02 John Cooper
2006-05-12 14:45 ` Bart Schaefer
2006-05-10 9:22 John Cooper
2006-05-10 17:28 ` Bart Schaefer
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=DD74FBB8EE28D441903D56487861CD9D09717293@lonpexch01.citrite.net \
--to=john.cooper@eu.citrix.com \
--cc=schaefer@brasslantern.com \
--cc=zsh-users@sunsite.dk \
/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).