[augeas-devel] How to match/delete commented lines with specific text?
Dan Mahoney (Gushi)
augeas at gushi.org
Mon Nov 16 11:24:29 UTC 2020
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) <augeas at gushi.org> 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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>
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>
>
> --
> Raphaël PinsonInfrastructure Developer & Training Leader
> +41 21 619 10 65
> Camptocamp SA
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>
> 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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