> /dev/null 2>&1

FreeBSD debug rc.d script

2018-03-31T10:05:00+00:00

Debugging rc.d scripts can be… always remember to set

sysrc rc_debug="YES"
sysrc rc_info="YES"

or set -x flag in rc script

$ printf '%s\n' 1a 'set -x' . w | ed -s /etc/rc.d/serviceScriptName

Fedora kernel lock

2018-03-25T13:15:00+00:00

$ sed -i -e "s/UPDATEDEFAULT=yes/UPDATEDEFAULT=no/" /etc/sysconfig/kernel

Fedora searching for space on /

2018-03-25T13:00:00+00:00

# let's check for journal disk space
$ journalctl --disk-usage
Archived and active journals take up 11.0G in the file system.

# time to clean up
$ journalctl --vacuum-time=1d
Deleted archived journal ...
Deleted archived journal ...
Deleted archived journal ...

Vacuuming done, freed 10.4G of archived journals from ... .

$ du -csh /var/cache/PackageKit/* | sort -h
5G      /var/cache/PackageKit/25
3.1G    /var/cache/PackageKit/26
1.2G    /var/cache/PackageKit/27
9.3G    total


$ pkcon refresh force -c -1
Refreshing cache                    [=========================]
Loading cache                       [=========================]
Downloading repository information  [=========================]
...
...
...
Finished                            [=========================]


# I don't need cache from older releases...
$ rm -rf /var/cache/PackageKit/25 /var/cache/PackageKit/26

$ du -csh /var/cache/PackageKit/* | sort -h
192M    /var/cache/PackageKit/27
192M    total

Cleaning after doF*&r

2017-11-01T18:00:00+00:00

# kill all running docker containers
$ docker kill $(docker ps -q)

# remove all containers
$ docker rm $(docker ps -aq)

# remove all images
$ docker rmi $(docker images -q)

# remove unused volumes
$ docker volume rm $(docker volume ls -qf dangling=true)

# clean network interfaces
$ docker network rm $(docker network ls | awk '$3 == "bridge" && $2 != "bridge" { print $1 }')

ESXi 5 and nested virtualization

2017-02-24T10:00:00+00:00

Trying to use virtualization inside a guest OS but error pops up?

KVM: no hardware support

on a ESXi host one can easy turn on the nested virtualization by editing the .vmx file

$ vim-cmd vmsvc/getallvms

make a note of vmID, file name and data store

$ cat << EOF >> /vmfs/volumes/$DATA_STORE/$FILE_NAME.vmx
vhv.enable = "TRUE"
EOF

$ vim-cmd vmsvc/reload $vmID

MySQL reset password

2017-02-01T19:00:00+00:00

Sometimes passwords are lost …, however in most cases we can find a workaround and reset the missing password.

First stop MySQL service, then we can start it in background without loading grant table.

$ mysqld_safe --skip-grant-tables --skip-networking &

Now we can connect to MySQL without password … Update root password:

$ mysql -e " \
  UPDATE mysql.user \
  SET \
    authentication_string = PASSWORD('new_password') \
  WHERE \
    User = 'root' \
  AND \
    Host = 'localhost' \
;"

All done, time to stop current running instance and start MySQL service as normal.

$ pkill mysql

FreeBSD ttyv0 auto login

2017-01-30T13:00:00+00:00

Sometimes there’s a need for auto login user over serial or ttyv

$ cat << EOF >> /etc/gettytab
autoLogin.Pc:\
  :ht:np:sp#9600:al=USER_NAME
EOF

$ grep ^ttyv0 /etc/ttys
ttyv0 "/usr/libexec/getty autoLogin.Pc"   xterm on  secure

/etc/gettytab(5), /etc/ttys(5)

Ansible custom Python interpreter

2016-12-09T10:16:00+00:00

ansible_python_interpreter - target host python path, useful for systems with multiple Python interpreters or not located at /usr/bin/python.

You can change interpreter location using host variables.

freebsd_host    ansible_python_interpreter=/usr/local/bin/python

Or by playbook variables.

---
- name: main build
  hosts: freebsd_host
  vars:
    ansible_python_interpreter: "/usr/local/bin/python2"
  roles:
    - common

FreeBSD DHCP Preferred DNS

2016-12-08T12:00:00+00:00

When you system is configured to use DHCP.

$ sysrc -n ifconfig_re0
DHCP

/etc/resolv.conf file will be regenerated on each system boot via /sbin/dhclient-script.

However one would prefer to use Public DNS Servers instead the ones provided by the DHCP server.

According to dhclient-script man page, we can change the behavior by overeating the add_new_resolv_conf function in /etc/dhclient-enter-hooks file.

$ cat << EOF > /etc/dhclient-enter-hooks
add_new_resolv_conf() {
       return 0
}
EOF

Now we can safely edit /etc/resolv.conf file - all changes will be persistent across system reboots.

FreeBSD securelevel

2016-11-25T19:00:00+00:00

Securelevel is a security mechanism implemented in the kernel.

To check current ‘secure level’:

$ sysctl kern.securelevel
kern.securelevel: 2

To change / raise ‘secure level’:

$ sysctl kern.securelevel=2

To enable ‘secure level’ on boot:

$ sysrc kern_securelevel_enable="YES"
kern_securelevel_enable:  -> YES

$ sysrc kern_securelevel="2"
kern_securelevel:  -> 2

FreeBSD security levels