Re: nother bash question
On Monday 13 June 2016 05:21:23 tomas@tuxteam.de wrote:
> On Mon, Jun 13, 2016 at 10:19:46AM +0200, Thomas Schmitt wrote:
> > Hi,
> >
> > Gene Heskett wrote:
> > > if test ${InMail} = "gene"
> > > bin/mailwatcher: line 66: test: =: unary operator expected
> >
> > The syntax problem is most probably about missing "-quotes around
> > the variable ecaluation ${InMail} which would have to be empty to
> > cause the message:
>
> Agreed.
>
> If I may add something -- one of the most difficult things for shell
> novices to wrap their head around is the interaction of command line
> expansion and the commands themselves. This is one of the things
> which make the shell very powerful [1], but you gotta get used to it.
>
> Let's walk through your problem case (note that I'm restating
> what Thomas said. It's just I know it's difficult and bears some
> repeating :)
>
> You wrote:
>
> test ${InMail} = "gene"
>
> Now the shell gets a first chance at it. Suppose ${InMail} is empty.
> After variable expansion, you got:
>
> test = "gene"
>
> (${InMail} was empty, so it gets replaced by nothing). Now that's
> what the "if" gets fed with. It responds with "Eek! You told me
> to compare *two* things and there's just one!
>
> One could argue "unary operator expected" is a strange way to
> restate this. I didn't check, but I guess we're seeing too
> deep into the bowels of if's parser.
>
> The solution is, as Thomas said, to put ${InMail} in double quotes.
> It almost always is. The better solution is, of course: always
> try to mentally follow what happens: first, expansion; then command.
Well, while the double quotes fixed it, the original actually worked.
The target action of sending kmail a getmail command was carried out,
Another time killer was doing a pidof -s kmail 3x in the main loop, that
is handled by the while, do, done around it all. So I just took that
out.
And I'm still puzzled. This is a single incoming mail:
+ InMail=_OLB,AltXXB.coyote
+ test _OLB,AltXXB.coyote = gene
+ test _OLB,AltXXB.coyote = gene-from_linda
+ test _OLB,AltXXB.coyote = amanda
all test failed so back at the while pidof -s kmail
++ pidof -s kmail
+ '[' 5179 ']'
kmail is there, launch the inotifywait session.
++ /usr/bin/inotifywait -q -e close --format %f /var/spool/mail/
+ InMail=gene
+ test gene = gene
+ /opt/trinity/bin/dcop kmail KMailIface checkMail
+ date -R
+ echo gene
back at the top of the while
++ pidof -s kmail
+ '[' 5179 ']'
++ /usr/bin/inotifywait -q -e close --format %f /var/spool/mail/
So here inotifywait is seeing kmail's close as it read the file and
zeroed it
+ InMail=gene
+ test gene = gene
+ /opt/trinity/bin/dcop kmail KMailIface checkMail
+ date -R
+ echo gene
++ pidof -s kmail
+ '[' 5179 ']'
++ /usr/bin/inotifywait -q -e close --format %f /var/spool/mail/
So its getting 2 checkmails because it is seeing its own activities. Put
in a sleep 1 after send the getmail to kmail to see if thats enough time
killer to miss that. Wasn't enough trying sleep 2 before relaunching
inotifywait now. And watching paint dry, only denied spam or nothing so
far.
Send this, so I'll get the echo as a test msg. :)
> regards
>
> [1] "expressive" might be the more correct term.
>
> -- tomás
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
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