Re: Set verbose Flag Inside if-block

[Dennis Williamson]

On Sun, Apr 16, 2023 at 1:24 PM Sysadmin Lists <sysadmin.lists@mailfence.com>
wrote:

> [ resending with proper subject line]
>
> > Message: 2
> > Date: Sun, 16 Apr 2023 10:42:29 +0200
> > From: Andreas Kusalananda Kähäri <andreas.kahari@abc.se>
> > To: Sysadmin Lists <sysadmin.lists@mailfence.com>
> > Cc: help-bash@gnu.org
> > Subject: Re: Set verbose Flag Inside if-block
> > Message-ID: <ZDu09W09cknzRrnZ@harpo.local>
> > Content-Type: text/plain; charset=utf-8
> >
> > > $ if true; then set -ve; echo $-; echo foo bar baz; set -ve; fi
> > > ehimvBHs
> > > foo bar baz
> >
> > Using set -v causes the shell to print the input lines *as they are
> > read*.  The line that contains the "set -v" command has already been
> > read, so it won't be outputted.
> >
> > >
> > > $ set -ve; if true; then echo $-; echo foo bar baz; set -ve; fi
> > > set -ve; if true; then echo $-; echo foo bar baz; set -ve; fi
> > > ehimvBHs
> > > foo bar baz
> >
> > No diference here, the line has already been read.
> >
> > --
> > Andreas (Kusalananda) Kähäri
> > SciLifeLab, NBIS, ICM
> > Uppsala University, Sweden
> >
> > .
>
> That's not what's happening. Breaking up that command line into newlines
> shows
> the bug.  The first version should echo everything inside the if-statement
> after the
>  'set -ve' but doesn't. It's treating the entire if-block as a single
> command.
>
> $ cat tmpfile.sh
> if true
> then
>         set -ve
>         echo $-
>         echo "foo bar baz"
>         set +ve
> fi
>
> $ ./tmpfile.sh
> ehvB
> foo bar baz
>
> $ cat tmpfile.sh
>         set -ve
> if true
> then
>         echo $-
>         echo "foo bar baz"
>         set +ve
> fi
>
> $ ./tmpfile.sh
> if true
> then
>         echo $-
>         echo "foo bar baz"
>         set +ve
> fi
> ehvB
> foo bar baz
>
>
> --
> Sent with https://mailfence.com
> Secure and private email
>
> Do your test twice: once to set verbose mode and the second time, after a
newline, to do things you need.
mytest=true
if "$mytest"
then
    set -v
fi
# verbose is only just now on, assuming the test is true
if "$mytest"
then
    do_stuff_verbosely
fi
set +v

It might show a few more lines than you wanted.

Otherwise, use set -x and perhaps unset PS4. But this will show everything
expanded.
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