Roundtable July 2024

roundtable@muug.ca

6 participants
5 discussions

Beautiful shell script example
by Adam Thompson 30 Jul '24

30 Jul '24

https://hackaday.com/2024/07/29/getting-linux-process-list-without-forking-… I wish I could hire the author of the script. -Adam Get Outlook for Android<https://aka.ms/AAb9ysg>

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Subdomain wildcard in Bind-style DNS editing
by Hartmut W Sager 24 Jul '24

24 Jul '24

I have a question about subdomain wildcards in Bind-style DNS editing, so that I can more conveniently edit DNS zone files to implement Fastmail's support of MX records specifying "*.mydomain.com." for e-mail at subdomains. (Yes, Fastmail's documentation states their support for this.) Now, in Bind-style DNS, we have valid short notations for full FQDN in the name field (the left side) as follows: "@" = "mydomain.com." "abc" = "abc.mydomain.com." So my question is, might the following also be valid? "*" = "*.mydomain.com." "*.@" = "*.mydomain.com." Hartmut

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RHEL latest package?
by Trevor Cordes 20 Jul '24

20 Jul '24

I finally gained access to the documentation for RHEL for a dedicated-hosting RHEL server I work on. But I find it hard to figure out where to go in there to find much of anything. And google doesn't seem to index what it is I need, maybe because of the paywall? I'm trying to figure out 2 things: 1. How can I tell what is the latest rpm/version RH has put out for httpd? I'm talking stock RHEL-supplied, not IUS/EPEL or whatever 3rd party. I know in Fedora this would be simple with bodhi/koji and/or simple rpmfind. 2. How can I tell if my RHEL box is setup to receive updates? Dnf works to install packages, but no updates seem to be coming across? I'm a bit worried because of the recent not-so-great apache/httpd bugs. I know RH has all this subscription stuff I normally don't have to mess with with Fedora, and I like to think the dedicated hoster set this all up properly, but I'm not sure how to tell. Thanks!

2 1

dialog(1) shell fd acrobatics question
by Adam Thompson 08 Jul '24

08 Jul '24

I’m trying to debug a shell script that uses dialog(1), which has the unfortunate habit of overwriting the debug output I wanted to see. After quite some time banging my head against the wall, I grabbed the source to dialog to look at their examples. Their examples follow a pattern I have NOT been following; I’m now looking at this trying to understand WTF it does: 1 exec 3>&1 2 returntext=`$DIALOG --title "RANGE BOX" --rangebox "Please set the volume..." 0 60 0 123 5 2>&1 1>&3` 3 returncode=$? 4 exec 3>&- so… ok. Line 1 duplicates FD 1 (stdout) into FD 3. That’s usually so we can mess with FD 1 later on and still have a handle to stdout. Good so far. Line 2 runs /usr/bin/dialog in a subshell, the options to dialog(1) are irrelevant here. I’m looking at the redirects. “2>&1” duplicates FD 1 into FD 2, effectively throwing away the handle to the inherited /dev/stderr and forcing stderr output onto stdout. That’s a good thing because dialog(1) reports its results onto stderr by default to avoid messing with curses(3) output. “1>&3” however, throws away stdout (FD 1), replacing it with FD 3 which is… already a copy of FD 1 ??? Line 3 is obvious. Line 4 closes FD 3. Not sure that we need to bother, but OK, cleaning up behind ourselves is usually a good thing. I get the need for swapping stdin/stderr, as dialog(1) – well, really curses(3) - uses stdout to paint the screen, so dialog(1) spits its results out on stderr to avoid conflicting. If we’re in a subshell trying to capture that output, we need to grab it just as dialog(1) exits – and $() assignment only captures stdout. But what’s the point of having FD 3 in this setup, if all we do is assign it to stdin inside the subshell and then forget about it? Can anyone see what I’m missing here? -Adam

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Last call for RSVP for MUUG BBQ
by Trevor Cordes 06 Jul '24

06 Jul '24

For those not subscribed to the newsletter, here's a final reminder that, if you haven't done so already, you need to RSVP for the MUUG BBQ coming up on July 9, 6:30pm. Please RSVP by July 7. More details can be found in the uber-rare Super Special Edition MUUGLines newsletter: https://muug.ca/pub/muuglines/pdf/muug2407.pdf Thanks! P.S. So far rain is forecasted, but we'll see as we get closer. If it's badly rained out, we'll reschedule if we can; see the newsletter for details! Subscribe to muug-announce to hear the latest. http://www.muug.ca/mailman/listinfo/muug-announce

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Roundtable July 2024