Inject hostname into kickstart

bgstack15 Uncategorized , , ,

The story

I have been learning how to automate my centos installations in my virtual environment. I’ve learned how to use the virsh command line to spin up a new vm the way I like, and to feed it a kickstart file. I also learned how to use kickstarts.

Set hostname automatically with a kickstart

In the main area of the kickstart file, include this line:

%include /tmp/network.ks

Include in your %pre section this section:

%pre
echo "network  --bootproto=dhcp --device=eth0 --ipv6=auto --activate --hostname renameme.ipa.example.com" > /tmp/network.ks
for x in $( cat /proc/cmdline );
do
   case $x in SERVERNAME*)
      eval $x
      echo "network  --bootproto=dhcp --device=eth0 --ipv6=auto --activate --hostname ${SERVERNAME}.ipa.example.com" > /tmp/network.ks
      ;;
   esac
done
%end

To paraphrase the post I’m duplicating for myself, you need the first echo redirection to the file in case there was no SERVERNAME= parameter given to the kernel.
When you boot, you need to include on the kernel command (usually the “linux” one), the value SERVERNAME=myhostname.

For my virsh command, that is:

vm=centos7-02a ; virt-install -n "${vm}" --memory 2048 --vcpus=1 --os-variant=rhel7.2 --accelerate -v --disk path=/var/lib/libvirt/images/"${vm}".qcow2,size=20 -l /mnt/public/Support/SetupsBig/CentOS-7-x86_64-Minimal-1511.iso  --initrd-inject=/mnt/public/Public/centos7-ks.cfg --extra-args "ks=file:/centos7-ks.cfg SERVERNAME=${vm}" --debug --network type=direct,source=eno1

References

  1. Install system-config-kickstart on Fedora 25 http://bytefreaks.net/gnulinux/fedora-25-workaround-to-install-system-config-kickstart 
    sudo dnf install
https://kojipkgs.fedoraproject.org/packages/system-config-date/1.10.9/3.fc25/noarch/system-config-date-1.10.9-3.fc25.noarch.rpm python-kickstart system-config-kickstart;
  2. https://sysadmin.compxtreme.ro/automatically-set-the-hostname-during-kickstart-installation/

List available packages from one repository

bgstack15 Uncategorized , , ,

For dnf

dnf list available --disablerepo=* --enablerepo=reponame

For dpkg (low-level package manager for apt)

ff() { for file in /etc/apt/sources.list.d/$1.list; do grep -iE "Package:" "/var/lib/apt/lists/$( cut -d' ' -f2 "${file}" | sed -r -e 'sX\/X_Xg;' -e 's/\<http.__//g;')Packages"; done; }
ff reponame

The story

For some reason it is harder to manage packages with apt: This is a main reason I don’t like to use it. I had to go write this crazy one-liner function to accomplish the same task that dnf provides with just two flags.
Also, the apt command here shows all the packages from that repository, regardless of its installed state. The dnf command will show only the ones available that are not already installed.

Watch for new processes and list them only once

bgstack15 Oneliner , ,

tl;dr

while true; do ps -ef | grep -iE "processname" | grep -viE "grep \-"; done | awk '!x[$10]++'

Discussion

Top shows everything currently running, and updates every so often (default is 2 seconds). But it has so much information for all the processes it does not show you the details of a single entry.
ps -ef or ps auxe only shows you the processes at that instant. You can run that in a loop piped to grep, but then it continues to show you the same things again and again.

Watch for new processes and list them only once

You can use this snippet to show you new entries for the process you’re looking for.

while true; do ps -ef | grep -iE "processname" | grep -viE "grep \-"; done | awk '!x[$10]++'

What this does is a while loop of all the processes. It updates constantly, because of the while true. The second grep command just prevents it from finding the first grep statement. Piping the whole thing to the special awk statement that removes duplicate lines makes it show only unique ones. And the awk $10 is the tenth column, which for me was the process parameter which is what I wanted to show the uniqueness of.

Cannot create items in Google Calendar

bgstack15 Uncategorized , , ,

If you use Google Calendar in Firefox, you might be unable to add calendar items. It displays this error: “Oops, we couldn’t create this event, please try again in a few minutes.”

A workaround was discovered by a user on the Google Calendar Help Forum.

harpseal said:

I think I found an answer. Delete the google calendar specific cookies and reload. After I did this it lets me create events. YAY! Hope this works for others.

References

Weblinks

  1. https://productforums.google.com/d/msg/calendar/8513S6SqGBY/KiubCBSKBwAJ

Remove comments from file but preserve strings

bgstack15 Oneliner , ,

Remove comments from file but preserve strings containing the comment symbol

sed '/#/!b;s/^/\n/;ta;:a;s/\n$//;t;s/\n\(\("[^"]*"\)\|\('\''[^'\'']*'\''\)\)/\1\n/;ta;s/\n\([^#]\)/\1\n/;ta;s/\n.*//' file

Explanation

/#/!b if the line does not contain a # bail out
s/^/\n/ insert a unique marker (\n)
ta;:a jump to a loop label (resets the substitute true/false flag)
s/\n$//;t if marker at the end of the line, remove and bail out
s/\n\(\(“[^”]*”\)\|\(‘\”[^’\”]*’\”\)\)/\1\n/;ta if the string following the marker is a quoted one, bump the marker forward of it and loop.
s/\n\([^#]\)/\1\n/;ta if the character following the marker is not a #, bump the marker forward of it and loop.

References

  1. Shamelessly plagiarized from http://stackoverflow.com/a/13551154/3569534

Slowcat

bgstack15 Uncategorized , ,

Have you ever wanted to slow down the terminal output? Use slowcat, by Dave Capella:

#! /usr/bin/python
# slowcat.py - print a file slowly
# author : dave w capella - http://grox.net/mailme
# date     : Sun Feb 10 21:57:42 PST 2008
############################################################
import sys, time

delay = .02

if len(sys.argv) > 1:
  arg = sys.argv[1]
  if arg != "-d":
    print "usage: %s [-d delay]" % (sys.argv[0])
    print "delay: delay in seconds"
    print "example: %s -d .02 < vtfile" % (sys.argv[0]) sys.exit() if len(sys.argv) > 2:
    delay = float(sys.argv[2])

while 1:
  try:
    print raw_input()
  except:
    break
  time.sleep(delay)

######################################################################
# eof: slowcat.py

The program is copyright (c) 2002-2008 – dave w capella – All Rights Reserved
It is distributed under the terms of the GNU Public License.
It includes NO WARRANTY and NO SUPPORT.

References

  1. https://grox.net/software/mine/slowcat/

An improvement upon while true loop

bgstack15 Oneliner , ,

The story

So normally when I want to see output for something, I’ll run a while true loop.

while true; do zabbix_get -s rhevtester.example.com -k 'task.converter_cpu'; done

That doesn’t always stop even when I mash ^C (CTRL+C).

The solution

So I offer my improvement. The way to stop the loop is obvious, and also I will explain it.

while test ! -f /tmp/foo; do zabbix_get -s rhevtester.example.com -k 'task.converter_cpu'; done

To stop the loop, in another shell just:

touch /tmp/foo

Edit terminal title from the command line

bgstack15 Oneliner , ,

tl;dr

export PROMPT_COMMAND='echo -ne "\033]0;NEW TEXT HERE\007"'

Edit terminal title from command line

To modify the window title directly, you just need to use this:

echo -ne "\033]0;NEW TEXT HERE\007"

But in a normal bash environment, your PROMPT_COMMAND will be executed before each display of the prompt, so to affect your interactive shell, you will need that export PROMPT_COMMAND.

References

Weblinks

  1. https://askubuntu.com/questions/22413/how-to-change-gnome-terminal-title