In order to create OSX installer on USB memory drive you need to:

  • Download the Mac OSX Yosemite installer from AppStore on you Mac.
  • Create installation media from Terminal by executing following command (remember to adjust YOURUSBVOLUME value):

    sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/YOURUSBVOLUME --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
  • Boot target Mac from USB by pressing ALT/OPTION key while powering-on the computer.
  • Remember to format target drive first with Disk Utility if you want to perform clean installation.

In case you wonder why your device does not connect as Modem via Bluetooth to the Mac OSX, or you cannot see COM port on Windows, your mobile device may not simply support or provide DUN (Dial Up Network) and/or SPP (Serial Port Profile) profile.

On Mac OSX I got following error, until I tried another device and/or starting by hand DUN service on a mobile/client machine:

cannot open /dev/cu.Bluetooth-Modem: Resource busy

Notes:

  • Read Bluetooth specification for Serial Port Profile.
  • Read Bluetooth specification for Dial-Up Network Profile.
  • Modern mobile phones / USB 3G dongles, unfortunately, do not provide direct AT/Hayes access to the Radio Modem anymore.
  • You can install DUN application for your smartphone, but it will be only a simple dummy wrapper imitating modem for simple applications, but they do not provide full modem functionality, beware, its a fake.
  • Its only necessary for devices to be paired first in order to get SPP/DUN working. If device does not provide serial port over bluetooth when devices are paired and online, probably its just not there implemented.

There are situations when you have a nice server out there, and you want/need someone to upload important files, but you only want to give them a minimal access to the system. You can use SSHD with sFTP and /sbin/nologin shell for that in chroot environment (dedicated limited userspace). Note that SCP in fact requires a working shell, so you need to use sFTP in this case..

Create a new user account with existing ftp group and /sbin/nologin shell:

# adduser

Alternatively you can modify an existing account to share:

# pw groupmod ftp -m username
# pw usermod username -s /sbin/nologin

You need to set correct permissions to the user home directory and public directory inside for upload:

# chown root:wheel /home/username
# mkdir /home/username/public
# chown username:ftp /home/username/public

Now modify the SSHD server configuration file /etc/ssh/sshd_config and append:

Match Group ftp
        ChrootDirectory         /home/%u
        ForceCommand            internal-sftp
        AllowTcpForwarding      no
        PermitTunnel            no
        X11Forwarding           no

Remember to restart the SSHD in order to apply new configuration:

# service sshd restart

Once the account is not necessary anymore remember to remove it:

# pw userdel username

If you want to perform a fresh installation of OSX 10.10 Yosemite on an older MacBook(Pro) you can obtain the installer with AppStore and then create the USB installation media.

In case you encounter an Installer Verification Error that prevents you from installing the new system try the following. Its not the system date not bad download as internets says.

This may also help you when encountering problems (i.e. USB Mass Storage) after system upgrade to Yosemite.

Try these boot keyboard shortcuts until you hear boot sound two times:

  • Cmd+Alt+R+P when powering on the Mac (NVRAM Reset)
  • Alt+Ctrl+Shift+PowerON alltogether (SMC Reset)

No problem, you are wolcome :-)

I have, finally, switched to Apple OS X. This is so close to my favorite FreeBSD (OSX is a Unix BSD / Darwin derivative) and it has all drivers and multimedia features working, that I think I will switch for good. This the simple, stable, and functional platform, where you can really focus on your work. Along with the MacPorts suite installed that provide access to the Open-Source / Free-Software I feel like home :-)

If you want to use GSM/3G/LTE modem on your FreeBSD box you need to use PPP and following configuration:

default:
 set log Phase Chat LCP IPCP CCP tun command
 ident user-ppp VERSION 
 set device /dev/cuaU0
 set phone *99\#
 set redial 5 10
 set speed 115200
 set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \
           \"\" ATH OK ATZ OK AT OK-AT-OK ATE1Q0 OK \
           AT+CFUN=1 OK-AT-OK \
           AT+CPIN? READY-AT+CPIN=\"1234\"-OK \
           AT+CGDCONT=1,\"ip\",\"internet\" OK \
           \\dATDT\\T TIMEOUT 40 CONNECT"
 set timeout 10
 enable dns
 set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.255 0.0.0.0
 add default HISADDR

In case you need to list directories only in reverse recursive order for automatic list generation for directory removal on package deinstallation, here goes an example sh+find script that should work on all Unix platforms:

#!/bin/sh
dirlevel=3;
while [ $dirlevel -gt 0 ]; do
 find /tmp -type d -depth $dirlevel
 dirlevel=`expr $dirlevel - 1`;
done

Q: How to change the default boot menu entry in GRUB2 used widely on Linux systems?

A: You can do it easily as root in three following steps:

  1. Run update-grub program and copy entry name that you want to make default.
  2. Edit /etc/default/grub and add or modify existing GRUB_DEFAULT="your_menu_entry_here".
  3. Run update-grub program again to update the grub bootloader configuration.



Mind-Over-Matter – this is my Virtual-Reality =)

cederom-florabo-virtual-reality-20140223

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