Hosting Operations
Read-only, sensitive outputShow Active MySQL Sessions
MySQL is slow or rejecting clients and you need a quick view of active sessions.
Command
mysql -e "show full processlist;"Before you run this
System impact: Read-only. Output may expose users, paths, tokens, keys, IPs, process arguments, or log details.
When not to use it: Do not use this as the kill step; inspect carefully before terminating sessions.
Expected output
Rows showing connection ID, user, host, database, command, time, state, and query text.
System impact
Read-only, sensitive output. Nothing changes. MySQL prints current sessions and queries.
Recovery / rollback: no state is changed.
When to use it
Use when MySQL feels saturated, slow, or overloaded.
When not to use it
Do not use this as the kill step; inspect carefully before terminating sessions.
next steps
Related commands
Find Long-Running MySQL Queries
One old query explained the whole slowdown.
mysql -e "select id,user,host,db,command,time,state,left(info,80) as info from information_schema.processlist where command <> 'Sleep' order by time desc limit 10;"
Show Active PostgreSQL Connections
The database was not down. It was full.
psql -X -A -F '|' -c "select pid,usename,datname,state,client_addr from pg_stat_activity order by state, pid;"
Check PostgreSQL Lock Waits
The outage was a queue, not a crash.
psql -X -c "select pid, wait_event_type, wait_event, state, left(query, 80) as query from pg_stat_activity where wait_event_type is not null order by pid;"
Show MySQL Database Sizes
The storage alert needed a database name.
mysql -e "select table_schema, round(sum(data_length + index_length)/1024/1024, 1) as mb from information_schema.tables group by table_schema order by mb desc;"
Check Whether PostgreSQL Is Accepting Connections
The database was running, but it was not ready.
pg_isready -h 127.0.0.1 -p 5432
Study mapping
Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.
Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.