On Mon, 16 Nov 2020, Raphaël Pinson wrote:

Hey Raphael (sorry if I miss the diacritics in your name). Thanks for replying -- this doesn't seem to be a very busy list. I've given it a try and something is still not clicking. I think it stems from the fact that comments are somehow "special".

Hi Dan,

You're not too far. You just missing the right operator for `regexp()`: 
https://github.com/hercules-team/augeas/wiki/Path-expressions#tips--tricks

  /files/etc/hosts/*[ipaddr =~ regexp("192\..*")]

Yes, I did find that. Let's use /etc/hosts as an example: The XML dump for a true /etc/hosts entry on my system is:

   <node label="2">
      <node label="ipaddr">
        <value>127.0.0.1</value>
      </node>
      <node label="canonical">
        <value>localhost</value>
      </node>
      <node label="alias">
        <value>localhost.my.domain</value>
      </node>
    </node>

So I can match on "ipaddr" or "canonical" or "alias".

With comments, there's NO SUB NODE to match on:

    <node label="#comment">
      <value>10.0.0.2           myname.my.domain myname</value>
    </node>

And the label for all nodes is just #comment (see above how /etc/hosts still has a "label" (2) that you can refer to it by, even if the file doesn't expose it -- lines in /etc/hosts don't start with numbers like this.

When constructing the regex you provided, "ipaddr" refers to the node label, and regexp("192\..*") to the value.

When using the only label I have (#comment), I get errors.

augtool> match /files/etc/hosts/[#comment = regexp(".*")]
error: Invalid path expression
error: empty name
/files/etc/hosts/|=|[#comment = regexp(".*")]

augtool> match /files/etc/hosts/*[label() = '#comment']
/files/etc/hosts/#comment[1] = $FreeBSD: releng/11.4/etc/hosts 109997 2003-01-28 21:29:23Z dbaker $
/files/etc/hosts/#comment[2] = Host Database
/files/etc/hosts/#comment[3] = This file should contain the addresses and aliases for local hosts that

Hrmm, so far as good -- at least this enumerates comments with an expression...But then:

augtool> match /files/etc/hosts/*[label() = '#comment'][value() = regexp(".*")]
error: Invalid path expression
error: empty name
/files/etc/hosts/*[label() = '#comment'][|=|value() = regexp(".*")]

I'm not sure what "|=| means in Augeas. I think it means "everything made sense up to here".

Could you give me a simple example that would, say, match any comment with the letter A in it?

-Dan


Raphaël


On Sat, Nov 14, 2020 at 10:39 PM Dan Mahoney (Gushi) <[email protected]> wrote:
      All,

      We're trying at the day job to use Augtool to clean up some
      in-the-os-by-default comments.  Under FreeBSD, this is what you might find
      in a stock /etc/pam.d/sshd:

      match /files/etc/pam.d/sshd/*
      /files/etc/pam.d/sshd/#comment[1] = $FreeBSD: releng/11.4/etc/pam.d/sshd
      197769 2009-10-05 09:28:54Z des $
      /files/etc/pam.d/sshd/#comment[2] = PAM configuration for the "sshd"
      service
      /files/etc/pam.d/sshd/#comment[3] = auth
      /files/etc/pam.d/sshd/1 = (none)
      /files/etc/pam.d/sshd/2 = (none)
      /files/etc/pam.d/sshd/#comment[4] = auth                sufficient
      pam_krb5.so             no_warn try_first_pass
      /files/etc/pam.d/sshd/#comment[5] = auth                sufficient
      pam_ssh.so              no_warn try_first_pass
      /files/etc/pam.d/sshd/3 = (none)
      /files/etc/pam.d/sshd/#comment[6] = account
      /files/etc/pam.d/sshd/4 = (none)
      /files/etc/pam.d/sshd/#comment[7] = account     required pam_krb5.so
      /files/etc/pam.d/sshd/5 = (none)
      /files/etc/pam.d/sshd/6 = (none)
      /files/etc/pam.d/sshd/#comment[8] = session
      /files/etc/pam.d/sshd/#comment[9] = session     optional        pam_ssh.so
      want_agent
      /files/etc/pam.d/sshd/7 = (none)
      /files/etc/pam.d/sshd/#comment[10] = password
      /files/etc/pam.d/sshd/#comment[11] = password   sufficient pam_krb5.so
      no_warn try_first_pass
      /files/etc/pam.d/sshd/8 = (none)

      And what I can't seem to find out how to do is match comments by name. For
      example, if I wanted to match any (or delete) any comment that include
      pam_krb5, how would I do it?

      As a comment, the usual parsing rules don't apply, and in all the wiki
      docs I can't find a clean example about "This is how you match a string by
      name".  (Call this a docbug maybe?)

      Help?

      -Dan

      PS, here's some of the things I've been trying -- am I just barking up the
      wrong tree here?

      augtool> match /files/etc/pam.d/sshd/#comment[ value = freebsd ]
         (no matches)
      augtool> match /files/etc/pam.d/sshd/#comment[ value = "freebsd" ]
         (no matches)
      augtool> match /files/etc/pam.d/sshd/#comment[ value() = "freebsd" ]
      error: Invalid path expression
      error: empty name
      /files/etc/pam.d/sshd/#comment[ |=|value() = "freebsd" ]
      augtool> match /files/etc/pam.d/sshd/#comment[ value = regex("freebsd") ]
      error: Invalid path expression
      error: empty name
      /files/etc/pam.d/sshd/#comment[ value = |=|regex("freebsd") ]
      augtool> match /files/etc/pam.d/sshd/#comment[ value = regexp("freebsd") ]
      error: Invalid path expression
      error: type error
      /files/etc/pam.d/sshd/#comment[ value = regexp("freebsd") ]|=|
      augtool> match /files/etc/pam.d/sshd/#comment[ value = regexp("freebsd") ]
      error: Invalid path expression
      error: type error
      /files/etc/pam.d/sshd/#comment[ value = regexp("freebsd") ]|=|
      augtool> match /files/etc/pam.d/sshd/#comment[ regexp("freebsd") ]
      error: Invalid path expression
      error: type error
      /files/etc/pam.d/sshd/#comment[ regexp("freebsd") ]|=|
      augtool> match /files/etc/pam.d/sshd/#comment[ regexp(freebsd) ]
      error: Invalid path expression
      error: type error
      /files/etc/pam.d/sshd/#comment[ regexp(freebsd) ]|=|
      augtool> match /files/etc/pam.d/sshd/#comment[ regexp(/freebsd/) ]
      error: Invalid path expression
      error: empty name


      --

      --------Dan Mahoney--------
      Techie,  Sysadmin,  WebGeek
      Gushi on efnet/undernet IRC
      FB:  fb.com/DanielMahoneyIV
      LI:   linkedin.com/in/gushi
      Site:  http://www.gushi.org
      ---------------------------

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--
Raphaël PinsonInfrastructure Developer & Training Leader
+41 21 619 10 65
Camptocamp SA
EPFL Innovation Park, Bât A
1015 Lausanne

www.camptocamp.com



--

"Is Gushi a person or an entity?"
"Yes"

-Bad Karma, August 25th 2001, Ezzi Computers, Quoting himself earler, referring 
to Gushi

--------Dan Mahoney--------
Techie,  Sysadmin,  WebGeek
Gushi on efnet/undernet IRC
FB:  fb.com/DanielMahoneyIV
LI:   linkedin.com/in/gushi
Site:  http://www.gushi.org
---------------------------
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