Launching SQL Server on Linux in Single User Mode

There was a question this morning on the SQL Server Community Slack channel from SvenLowry about how to launch SQL Server on Linux in Single User Mode. Well you’ve heard everyone say, it’s just SQL Server…and that’s certainly true and this is another example of that idea.

The command line parameters from the sqlservr binary are passed through into the SQLPAL managed Win32 SQL Process. So let’s check out how to do this together…

First, you’ll want to switch to the user mssql and you can do that with this command

bash-4.2$ sudo su mssql –


What’s happening here is we’re using sudo to switch our user’s security context to the user mssql. This is the account that SQL Server normally runs under. That last dash there is to load the mssql user’s shell, rather than ours.
 
Next, we need to launch the /opt/mssql/bin/sqlservr binary with the -m parameter
 

bash-4.2$ /opt/mssql/bin/sqlservr -m 


Here’s the output from the console while SQL Server is starting up. 

2017-11-09 12:53:18.70 Server      Microsoft SQL Server 2017 (RTM-CU1) (KB4038634) – 14.0.3006.16 (X64) 

Oct 19 2017 02:42:29 

Copyright (C) 2017 Microsoft Corporation

Developer Edition (64-bit) on Linux (CentOS Linux 7 (Core))

2017-11-09 12:53:18.70 Server      UTC adjustment: -6:00

2017-11-09 12:53:18.70 Server      (c) Microsoft Corporation.

2017-11-09 12:53:18.70 Server      All rights reserved.

2017-11-09 12:53:18.70 Server      Server process ID is 4120.

2017-11-09 12:53:18.70 Server      Logging SQL Server messages in file ‘/var/opt/mssql/log/errorlog’.

2017-11-09 12:53:18.70 Server      Registry startup parameters: 

-d /var/opt/mssql/data/master.mdf

-l /var/opt/mssql/data/mastlog.ldf

-e /var/opt/mssql/log/errorlog

2017-11-09 12:53:18.70 Server      Command Line Startup Parameters:

-m

Output omitted…

2017-11-09 12:53:19.50 spid4s      SQL Server started in single-user mode. This an informational message only. No user action is required.

Output omitted…

2017-11-09 12:53:19.90 spid4s      Always On Availability Groups was not started because the SQL Server instance is running in single-user mode.  This is an informational message.  No user action is required.

Output omitted…

2017-11-09 12:53:20.62 spid4s      Recovery is complete. This is an informational message only. No user action is required.


From here, you can go about what ever task it is you needed single user mode for.
 
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