How to fix Crontab -e - You are not allowed to use this program (crontab)

Question: I've received a new server and logon, trying to use Crontab but getting this error message: You (your_logon) are not allowed to use this program (crontab) See crontab(1) for more information How can I fix? Answer: It looks like you are experiencing a situation where only root can use crontab - but other logon accounts require some extra steps. On Linux there are two files which control the access to crontab: /etc/cron.allow /etc/cron.deny You will need to add the logon account to the /etc/cron.allow file. The way to add the logon account is to --su to root and then... Read more →

How to easily install Podman on Red Hat Linux

If you have RHEL 7.6 use : subscription-manager repos --enable=rhel-7-server-extras-rpms yum install podman yum install podman containernetworking-plugins (optional command) yum install podman-docker (optional command) Once you've confirmed Podman is installed , you can start to Pull images onto Podman --view app logs podman container logs --list podman containers podman ps -a --remove podman containers podman rm --stop a container podman stop --remove all podman images- be careful this will remove all images podman image rm -a --podman ports exposed podman inspect $CONTAINER -f='{{.NetworkSettings.Ports}}{{.HostConfig.PortBindings}}' --ports listening on Linux netstat -tulpn | grep... Read more →

How to change PostgreSQL database data directory

Question: The Postgres data_directory is showing a value via the SHOW data_directory command. postgres=# SHOW data_directory; data_directory ------------------------ /var/lib/postgres/data (1 row) How can I change the database directory to another directory? Answer: The steps below are a standard approach. The steps will vary according to specific requirements, and may require a more customised approach Step 1 - Identify current data directory path SHOW data_directory; Step 2- Stop Postgresql services systemctl status systemctl stop Step 3 - create a blank directory on the target path e.g mkdir /mydirectory/data --change ownership to the postgres user chown postgres:postgres /mypostgres/data Step 4... Read more →

How to fix Table doesn't exist in engine error for MariaDB Error 1932

Question: When attempting a mysqldump on one of the databases on a MariaDB server with this command I received the error message mysqldump: Got error: 1932: "Table 'schema1.myTable' doesn't exist in engine" when using LOCK TABLES mysqldump -u myun -p database_name > /mariadb/backups/mydb1171117.sql Description: Backup of [~myDB1~] MySQL database failed. The error message [~mysqldump: Couldn't execute 'show create table `my_code`': Table 'mydb1.my_code' doesn't exist in engine (1932) ~] is received during backup. Source: myserver1, Process: MySqlBackupChil How can I fix? In summary - some files were moved around and this has caused the issue Answer:I've found this error message appears... Read more →

How to use auto-increment with PostgreSQL sequence

A developer contacted me to to tell me they were experiencing problems with enabling an auto-increment on a PostgreSQL table.He wanted to know if the privileges assigned to his user credentials had the right level of permission to create a sequence. I reviewed the privileges and identified some missing details: GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA myschema1 TO user1; As a test I logged on as the user's credentials and completed some simple validation tasks to confirm they could complete a CREATE SEQUENCE and add to a table. Step 1 : Create a simple SEQUENCE CREATE SEQUENCE myschema1.jvtest_seq;... Read more →

Announcing Powerful Rules for Disruptors with MongoDB

An interesting presentation highlighting the power of keeping the pressure on but making as many friends as possible - to create change . Modernizing and rethinking legacy platforms can be a daunting task. This presentation describes cultural buttons to push - and how to start small , but keep growing. Starting small - allows developing expertise at a granular level which is the foundation of hyperscale These are some highlights from the presentation- with a link to the presentation Rules for Disruptors - Making, Managing and Scaling the Case for Change with MongoDB by Jeff Needham - Architect The most... Read more →

How to fix - Cannot connect to the Docker daemon

Question: I'm getting this error message when attempting to connect to the Docker daemon ? Can you supply a method to fix this issue docker info Cannot connect to the Docker daemon at tcp://localhost:2375/usr/lib/systemd/system/docker.socket. Is the docker daemon running? Answer: I've experienced this problem previously - and this is the way I worked around the problem.Let me know if this doesn't fix the issue Add your self to the docker group usermod -aG docker $USER Fix permissions on docker socker and command. sudo chgrp docker /usr/bin/docker sudo chgrp docker /var/run/docker.sock $ ll $(which docker) -rwxr-xr-x 1 root docker 18991768 08.07.2017... Read more →

How to master KSQL with cheat-sheet

KSQL is the the streaming SQL Engine for the real time data processing of Kafka. These are some of the commands --check KSQL is running ps aux | grep ksql --check KSQL error logs (if using Confluent) confluent log ksql-server --list created streams LIST STREAMS --View the structure of STREAM DESCRIBE mySTREAM_NAME --display all topics SHOW TOPICS --display values in topic PRINT 'topic_name' Read more on Apache Kafka How to Rock Apache Kafka with a cheat-sheet Read more →

How to find Default Access Privileges on PostgreSQL with pg_default_acl

This is a basic code sequence to set the Default Access Privileges on a PostgreSQL database. This example defines future privileges for future objects for this user. But what if you want to view the stored information about default access privileges ? There is a view called pg_default_acl ALTER DEFAULT PRIVILEGES IN SCHEMA myschema GRANT ALL PRIVILEGES ON TABLES TO myuser; ALTER DEFAULT PRIVILEGES IN SCHEMA myschema GRANT ALL PRIVILEGES ON SEQUENCES TO myuser; If you want to view the default access information stored you can use the PG_DEFAULT_ACL view. The default record set i.e SELECT * FROM PG_DEFAULT_ACL will... Read more →

MongoDB 4.2.7 Bug - Off-by-one overflow in block-modification bitmaps for incremental backup

A bug on MongoDB 4.2.7 has been identified- and a fix is included in 4.2.8 .Certain conditions are required for the bug to appear - detailed below. Based on the supporting documentation for the MongoDB 4.2.7 bug to occur: Must be running MongoDB 4.2.7. Managed by Ops Manager 4.2.13+ or managed in Cloud Manager with MongoDB agent version v10.14.0+. Incremental backups are enabled. The DB server has collection files greater than 2GB on disk. These collections are modified anytime after backups are enabled. If these conditions are met , there is a possibility that MongoDB will improperly overwrite memory. Read... Read more →