Category: System Administration

MySQL: Moving Data From One Table To Another

Our OpenHAB persistence data is stored in MySQL. There’s an “items” table which correlates each ItemName string to an ItemID integer. There are then Item#### tables that store persistence data for each item. If you rename an item, this means a new table is created and previous persistence data is no longer associated with the item. For some items, that’s fine — I don’t really care when the office light was on last month. But there’s persistence data that we use over a long term — outdoor temperature, luminance, electrical usage. In these cases, we want to pull the old data into the new table. There’s a quick one-liner SQL command that accomplishes this:

INSERT INTO NewTable SELECT * from OldTable;
e.g. INSERT INTO Item3857 SELECT * FROM Item3854;

You can drop the old table too:

DROP OldTable;

But I run a cleanup script against the item list so often don’t bother to remove tables one-off.

Adding member to MS Teams without admin rights or Graph API

# To run on Linux, you need the preview mode of AzureAD
# Register-PackageSource -Trusted -ProviderName ‘PowerShellGet’ -Name ‘Posh Test Gallery’ -Location https://www.poshtestgallery.com/api/v2/
# Install-Module -Name AzureAD.Standard.Preview

# Windows, the module is
# Install-Module -Name AzureAD

# I’m lazy and just typed my creds for a proof of concept; real implementation would use the SecureString thing in the connect-azuread. See:
# https://www.rushworth.us/lisa/?p=3294
connect-azuread

# Get the object ID for the group and the user
$objMyGroup = get-azureadgroup -SearchString “LJR Sandbox Team”
$objNewMember = get-azureaduser -searchstring “NewGuy”

# Add the user to the group
add-azureadgroupmember -ObjectID $objMyGroup.ObjectId -RefObjectID $objNewMember.ObjectId

Identifying System-Only AD Attributes

This information is specific to Active Directory. MSDN has documentation for each schema attribute — e.g. CN — which documents if the attribute is “system only” or not.

For an automated process, search at the base cn=schema,cn=configuration,dc=example,dc=com with the filter (&(ldapDisplayName=AttributeName))and return the value of systemOnly. E.G. this shows that operatingSystemServicePack is user writable.

***Searching...
ldap_search_s(ld, "cn=schema,cn=configuration,dc=example,dc=com", 2, "(&(ldapDisplayName=operatingSystemServicePack))", attrList,  0, &msg)
Getting 1 entries:
Dn: CN=Operating-System-Service-Pack,CN=Schema,CN=Configuration,dc=example,dc=com
systemOnly: FALSE;

You can also list all of the system-only attributes by using the filter (&(systemOnly=TRUE)) and returning ldapDisplayName

***Searching...
ldap_search_s(ld, "cn=schema,cn=configuration,dc=example,dc=com", 2, "(&(systemOnly=TRUE))", attrList,  0, &msg)
Getting 189 entries:
Dn: CN=OM-Object-Class,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: oMObjectClass; 

Dn: CN=Canonical-Name,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: canonicalName; 

Dn: CN=Managed-Objects,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: managedObjects; 

Dn: CN=MAPI-ID,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: mAPIID; 

Dn: CN=Mastered-By,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: masteredBy; 

Dn: CN=Top,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: top; 

Dn: CN=NTDS-DSA-RO,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: nTDSDSARO; 

Dn: CN=Application-Process,CN=Schema,CN=Configuration,dc=example,dc=com
lDAPDisplayName: applicationProcess; 
...

 

Asus Router NVRAM Usage

I had a really strange problem with an Asus router — the port forwarding disappeared. And while I could use the UI and put everything back in, it didn’t stick around. Turns out the NVRAM was full — there wasn’t anywhere to put the port forwarding rules (vts_rulelist). Fortunately, there were a few old DHCP reservations I was able to delete and free up some space. For future reference, the following command reports what is using the NVRAM.

nvram show | awk '{print length(), $0 | "sort -n -r"}' | cut -d"=" -f 1

Network Manager GUI

You can use nmcli to configure network interfaces controlled by NetworkManager. But, honestly, I don’t see any advantage to learning the cryptic CLI instead of using the cryptic config file stuff I’ve already learned. And yet … I need my server to have /etc/resolv.conf populated when it reboots. So I figured out how to launch the KDE system settings (assuming you’ve got the X display redirected to your host) — systemsettings5

Mine takes a few minutes to render, during which time the window is black and a handful of errors are written out to the console. But it got there eventually, and I was able to edit the network interface.