Problem Scenario: When logging into Linux Mint, the first and only field for text is a password prompt. The corresponding username is not shown. You do not understand this. How do you get Linux Mint to prompt for a username?
Solution Log in with the password of the user who just logged in. Go to Menu -> Administration -> Login Window. Uncheck "Automatically select the last logged in user." (When this setting is checked, the username is implied to be the most recent user who logged into the system.) Next time someone tries to log in, he/she will get a prompt to enter a username.
Problem scenario: You have a Windows 7 host with Oracle VirtualBox. You have a guest CentOS Linux virtual server. How do you connect to a CentOS VM using networking?
Miscellaneous: If you are looking for directions on how to give a Linux guest access to the Internet, these directions will work (assuming the host is running Windows).
Solution #1 In Oracle VirtualBox go to Devices -> Network -> Network Settings. For Adapter1 have the "Attached to" drop down be configured for "NAT." Go to "Advanced" and check the box for "Cable Connected." Click "Ok."
#2 Go to the Linux CentOS server. Enter this command:
ip addr show | grep inet | grep -v inet6 | grep -v 127.0.0.1 | awk '{print$2}'
Make a mental note of the IP address you find (e.g., 10.0.2.14), but you can ignore the CIDR (e.g., /24).
#3 In Oracle VirtualBox go back to Devices -> Network -> Network Settings. For Adapter1 go to "Advanced" and click the button for "Port Forwarding." If you find everything has been preconfigured, make a mental note of the Guest IP address and go to step #4. Otherwise click the icon of the green diamond with a green plus sign to add a rule. Make sure the rule, under any name, has the following settings:
"10.0.2.14" is just an example of a guest IP address. The Guest IP you should use should be the IP address found in step #2 above. Similarly, "127.0.1.1" is just an example of a Host IP address. If you have two or more guest machines, you may want to use "127.0.2.1" for one of the servers. This way you could connect to each of them with Putty.
Click "OK" and click "OK" again.
#4 Open Putty on the Windows host. Connect to the guest IP address -- in the example above for one server, it would be 127.0.1.1.
Problem scenario You are using PowerShell 3.0 on Windows 7 and you try to run the PowerShell command start-bitstransfer to download a large file. Running start-bitstransfer results in an error that says "Not Enough space on disk."
Solution Verify the size of the file. See if the destination directory/drive has sufficient space. If this error happens despite there being ample space available in the destination drive and destination directory compared to the size of the source media, see if the destination is using a FAT32 file system. Go to "My Computer." Right click the drive (e.g., H:) that is the destination of the download and go to Properties. On the "General" tab there is a section that says "File System." If it is FAT32, the file will not be downloaded if it is 4 GB or larger because that is too big for FAT32.
To change the file system type from FAT32, you can convert the file system to NTFS with this link.
Problem scenario: You are running Linux 7.x in Oracle VirtualBox on a Windows Professional 7 laptop. In the Linux server, you try to ping an IP address. You get "connect: Network is unreachable."
Solution
1. In the Oracle VirtualBox window of the server, go to Devices -> Network Settings -> Adapter 1
a) Go to Attached To: and choose "NAT"
b) Check the box for "Cable Connected"
2. On the client, modify this file /etc/sysconfig/network-scripts/ifcfg-enp0s3
a) Add these two lines, with no spaces, above the "ONBOOT" stanza without deleting other lines:
DNS1=8.8.8.8 DNS2=8.8.4.4
b) Change the "ONBOOT" stanza to be yes, like this (with no spaces):
ONBOOT=yes
c) Save the changes.
3. Reboot the client
4. If you are still having problems, you may want to see this posting.
Problem scenario: You want to install Linux on a laptop or workstation. You need to create bootable media with an .iso file that is over 7 GB. CDs and DVDs cannot support 7 GB. What do you create a bootable USB stick?
Solution This assumes you have downloaded the installation media (the .iso file) to your computer. For .iso files that are over 8 GB, you may need a USB stick that is greater than 8 GB. Assuming you have a large enough USB stick, use the portable version of Rufus. Then follow these steps:
1. Open Rufus (the portable version). 2. For the device that will be bootable, all of its data will be destroyed. Back up the data now. 3. The "Device" drop down menu at the top of Rufus is the destination of the bootable media. Change this to the drive letter that will become bootable. 4. In the Format Options, there is an option for "Create a bootable disk using ..." section. Click the icon of the CD to select the correct source of the .iso file. 5. The rest of the default settings for Rufus (the portable version) can remain the same. Click "Start." 6. You may get a pop up window for "ISOHybrid image detected." Keep the "Write in ISO Image mode" selected. Click "Ok." If you do not get the pop up prompt, go to step #7. 7. You will get a prompt about deleting all the data on the destination drive you chose in step #3. Click "Ok" to proceed. Or click cancel if you forgot to back up some of the data. For a 16 GB USB stick, it may take 25 to 50 minutes. Warning: when Rufus is finished, there will be no messages. You will see the Rufus application that will look very similar to the way it looked when you started.
Problem scenario: You have a drive "H:" that is using FAT32. You want to conver it to NTFS. You open PowerShell as Administrator. You delete the files on drive H:. You run this command:
convert h: /fs:ntfs
You see this message "File and folder verification is complete." It hangs and never completes.
Solution Do not use PowerShell. Follow these three steps: #1 Open a regular (non-PowerShell) command prompt. #2 Run this command: chkdsk /F h: #3 Run this command: convert h: /fs:ntfs
Problem scenario: You want to transfer files between a host machine running Oracle VirtualBox and a guest server. By sharing media, your Oracle VirtualBox is much more useful. How do you configure a folder to be shared between the host machine that runs Oracle VirtualBox and a virtual guest OS?
Solution These directions are for Oracle VirtualBox running on a Windows 7 Professional host with a guest virtual server running Linux, specifically CentOS 7.x. If you want to have a USB stick be the shared drive, physically insert it into your Windows desktop now. Create a folder on this USB stick.
1. a) Identify a folder on your Windows host machine that you want to be a share with your Linux guest VM.
b) This step only needs to be performed one time. You may be able to skip this step if it has been performed previously. In Oracle VirtualBox open the CentOS VM. Go to Devices -> Shared Folders -> Shared Folder Settings. Click the folder icon with a green plus sign (to add a folder).
Then go to the "Folder Path" drop down then find the folder on the Windows server you want to add. For folder name, enter whichever name you want. For these directions we will call it "contint". If you are actually following these directions and not just reading them, replace "contint" with the name you chose here. Check the options for "Auto-mount" and "Make Permanent." Click "Ok."
2.a. On the Linux guest, run this command: yum update kernel* b. Reboot the guest server. c. In Oracle VirtualBox Go to Devices -> Insert Guest Additions CD Image. Unless you received an error, proceed to step #3. If you get an error and failure do the following: verify VBoxGuestAdditions.iso is on your Windows host. Then in Oracle VirtualBox go to Devices -> Optical Drives -> Choose disk image. Then navigate to the VBoxGuestAdditions.iso file.
3. This step only needs to be performed one time. You may be able to skip this step if it has been performed previously. On the Linux guest VM, run these five commands:
mkdir /media/VirtualBoxGuestAdditions mount -r /dev/cdrom /media/VirtualBoxGuestAdditions yum -y install bzip2 gcc make perl kernel-devel KERN_DIR=/usr/src/kernels/`uname -r` export KERN_DIR
If applicable, we find this message to be ignorable: "Could not find the X.org or XFree86 Window System, skipping."
4. Run these commands on the Linux guest VM: mkdir /mnt/windows-share mount -t vboxsf contint /mnt/windows-share # where "contint" was the name chosen in step 1. b.
Problem scenario: You are trying to install Guest Additions on a Linux server. You mount the CD/DVD/.iso through Oracle VirtualBox to /media/VirtualBoxGuestAdditions. On the host virtual server the /media/VirtualBoxGuestAdditions (the directory where the CD/DVD/.iso was mounted) has no files. You try to unmount the device and remount the device. But you see no files. You are unable to run "./VBoxLinuxAdditions.run" because the file is not where it should be. What do you do to solve this problem?
Solution Reboot the Linux server. Mount the device again (e.g., with a command like this "mount /dev/cdrom /media/VirtualBoxGuestAdditions").
Problem scenario: yum commands are failing. You get this error after running a yum command: "File /var/cache/yum/i386/7/epel/metalink.xml does not exist"
Solution Remove EPEL. Use this command: "yum remove epel-release"
