Many times, you need to get informations from MSDB database.
I’m going to share some simple scripts that can help you.

Increase SQL Agent History Retention
If you have many jobs that run frequently, you may want to increase the retention to use it later on to troubleshoot.

Use the following script:

USE [msdb]
GO
EXEC [dbo].[sp_set_sqlagent_properties]
      @jobhistory_max_rows=10000,
      @jobhistory_max_rows_per_job=1000

Delete old entries in the backup and restore history tables in msdb database
To delete old entries in the backup and restore history tables in msdb database, you can use a stored procedure sp_delete_backuphistory.

Following Stored Procedure can be executed with parameter which takes days of history to keep. In following example 30 is passed to keep history of month.

USE [msdb]
GO
DECLARE @Delete_Date [datetime]
SET @Delete_Date = GETDATE() - 30
EXEC sp_delete_backuphistory @Delete_Date

To delete all information about the specified database

USE msdb;
GO
EXEC sp_delete_database_backuphistory @database_name = 'AdventureWorks';

Search SQL Server Agent Job Steps or Stored Procedure
Search a specific Job key word in the steps of all jobs

USE [msdb]
GO
SELECT    j.job_id,
     s.srvname,
     j.name,
     js.step_id,
     js.command,
     j.enabled
FROM dbo.sysjobs j
JOIN dbo.sysjobsteps js
     ON   js.job_id = j.job_id
JOIN master.dbo.sysservers s
     ON   s.srvid = j.originating_server_id
WHERE     js.command LIKE N'%your_key_word_here%'