Полезные команды

Find largest files (Linux)

1️⃣ Find files larger than a specific size

Example: files larger than 500 MB:

• / — search from root (you can replace with /var, /home, etc.)

• 2>/dev/null — hides permission errors

Use -exec ls -lh

• ls -lh shows sizes in human-readable format (K, M, G).

• Output example:

-rw-r--r-- 1 root root 1.2G Jan 17 /var/log/mariadb/mariadb.log

-rw-r--r-- 1 www-data www-data 700M Jan 17 /var/log/drupal.log

Limit /var/log/messages

/var/log/messages is managed by rsyslog (or syslog/journald). To limit it:

You can create/modify a file, e.g., /etc/logrotate.d/messages:

Explanation:

• daily → check every day

• rotate 7 → keep 7 old logs

• compress → gzip old logs

• size 500M → rotate immediately if file > 500 MB

Then test rotation:

b) Optional journald approach

If your system uses systemd-journald (many modern CentOS/RHEL/Fedora):

Then restart journald:

This limits all journal logs including /var/log/messages if ForwardToSyslog=yes.

2️⃣ Limit /var/lib/mysql/mysql-slow.log

This is MariaDB’s slow query log. There are two ways:

a) Using logrotate

Create /etc/logrotate.d/mariadb-slow:

• size 500M → rotates if bigger than 500MB

• postrotate ... USR1 → tells MariaDB to reopen slow lo

b) Limit slow log directly in MariaDB

In /etc/my.cnf:

You cannot directly limit the size inside MariaDB, but with logrotate + USR1 signal you can safely manage it.

✅ Summary recommendation:

• /var/log/messages → logrotate or journald limit

• /var/lib/mysql/mysql-slow.log → logrotate + USR1 signal

• Optional: set daily rotation instead of size if you prefer predictable schedule