'Re: How to remove variable from GRUB environment block'

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List:       grub-help
Subject:    Re: How to remove variable from GRUB environment block
From:       Ulf Zibis <Ulf.Zibis () gmx ! de>
Date:       2013-02-16 17:08:18
Message-ID: 511FBD02.2030405 () gmx ! de
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Hi,

see my justification here: http://savannah.gnu.org/bugs/?38308

-Ulf

Am 16.02.2013 03:50, schrieb Wang Weber:
> Hi,
>
> Why do you want to remove the variable instead of just setting it to empty?
>
> 2013/2/13 Ulf Zibis <Ulf.Zibis@gmx.de <mailto:Ulf.Zibis@gmx.de>>
>
>     Am 12.02.2013 16:21, schrieb Andrey Borzenkov:
>
>         В Tue, 12 Feb 2013 14:57:53 +0100
>         Ulf Zibis <Ulf.Zibis@gmx.de <mailto:Ulf.Zibis@gmx.de>> пишет:
>
>
>             I'm not clearly sure, but I see different syntax in my grub.cfg, which I interpret as
>             "test for existence":
>
>         No. Both just test whether result of variable substitution is empty or
>         not. It is empty if variable is not defined or if it is defined but
>         empty.
>
>             if [ x"${feature_menuentry_id}" = xy ]; then
>                 ...
>
>             if [ "${prev_saved_entry}" ]; then
>                 set saved_entry="${prev_saved_entry}"
>             fi
>
>
>     Thanks for your clarification! But wouldn't this be a nice feature to have both?
>
>     I still bother what the difference is with the above syntax. Is there a syntax tutorial somewhere?
>
>     I guess, the following third syntax is redundantly the same:
>
>     if [ ! "${feature_menuentry_id}" = "" ]; then
>        ...
>
>
>
>     -Ulf
>
>
>     _______________________________________________
>     Help-grub mailing list
>     Help-grub@gnu.org <mailto:Help-grub@gnu.org>
>     https://lists.gnu.org/mailman/listinfo/help-grub
>
>

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    Hi,<br>
    <br>
    see my justification here: <a class="moz-txt-link-freetext" \
href="http://savannah.gnu.org/bugs/?38308">http://savannah.gnu.org/bugs/?38308</a><br>
  <br>
    -Ulf<br>
    <br>
    <div class="moz-cite-prefix">Am 16.02.2013 03:50, schrieb Wang
      Weber:<br>
    </div>
    <blockquote
cite="mid:CAAZN+A3LZ5OmBV-unRS9VNse=eafET4Dv8AXJTnDqASSvb14Xg@mail.gmail.com"
      type="cite">Hi,
      <div><br>
      </div>
      <div>Why do you want to remove the variable instead of just
        setting it to empty?<br>
        <br>
        <div class="gmail_quote">2013/2/13 Ulf Zibis <span dir="ltr">&lt;<a
              moz-do-not-send="true" href="mailto:Ulf.Zibis@gmx.de"
              target="_blank">Ulf.Zibis@gmx.de</a>&gt;</span><br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">Am
            12.02.2013 16:21, schrieb Andrey Borzenkov:<br>
            <blockquote class="gmail_quote" style="margin:0 0 0
              .8ex;border-left:1px #ccc solid;padding-left:1ex">
              <div class="im">
                В Tue, 12 Feb 2013 14:57:53 +0100<br>
                Ulf Zibis &lt;<a moz-do-not-send="true"
                  href="mailto:Ulf.Zibis@gmx.de" \
target="_blank">Ulf.Zibis@gmx.de</a>&gt;  пишет:<br>
                <br>
              </div>
              <blockquote class="gmail_quote" style="margin:0 0 0
                .8ex;border-left:1px #ccc solid;padding-left:1ex">
                <br>
                <div class="im">
                  I'm not clearly sure, but I see different syntax in my
                  grub.cfg, which I interpret as "test for existence":<br>
                </div>
              </blockquote>
              <div class="im">
                No. Both just test whether result of variable
                substitution is empty or<br>
                not. It is empty if variable is not defined or if it is
                defined but<br>
                empty.<br>
                <br>
                <blockquote class="gmail_quote" style="margin:0 0 0
                  .8ex;border-left:1px #ccc solid;padding-left:1ex">
                  if [ x"${feature_menuentry_id}" = xy ]; then<br>
                      ...<br>
                  <br>
                  if [ "${prev_saved_entry}" ]; then<br>
                      set saved_entry="${prev_saved_entry}"<br>
                  fi<br>
                </blockquote>
              </div>
            </blockquote>
            <br>
            Thanks for your clarification! But wouldn't this be a nice
            feature to have both?<br>
            <br>
            I still bother what the difference is with the above syntax.
            Is there a syntax tutorial somewhere?<br>
            <br>
            I guess, the following third syntax is redundantly the same:<br>
            <br>
            if [ ! "${feature_menuentry_id}" = "" ]; then<br>
               ...
            <div class="HOEnZb">
              <div class="h5"><br>
                <br>
                <br>
                -Ulf<br>
                <br>
                <br>
                _______________________________________________<br>
                Help-grub mailing list<br>
                <a moz-do-not-send="true"
                  href="mailto:Help-grub@gnu.org" \
target="_blank">Help-grub@gnu.org</a><br>  <a moz-do-not-send="true"
                  href="https://lists.gnu.org/mailman/listinfo/help-grub"
                  target="_blank">https://lists.gnu.org/mailman/listinfo/help-grub</a><br>
  </div>
            </div>
          </blockquote>
        </div>
        <br>
      </div>
    </blockquote>
    <br>
  </body>
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