komanda, matyti iš kurių IP buvo prisijungta prie ssh

 grep "sshd.*Accepted" /var/log/auth.log | awk '{print $11}' | sort | uniq

 grep "sshd.*Accepted" /var/log/secure | awk '{print $11}' | sort | uniq

php kodas, tikrinantis įmonės registracijos numerį

function validateCompanyRegistrationNumber($number) { if (strlen($number) != 9) { return false; } $weights = [1, 2, 3, 4, 5, 6, 7, 8]; $sum = 0; for ($i = 0; $i < 8; $i++) { $sum += $weights[$i] * (int) $number[$i]; } $checkDigit = $sum % 11; if ($checkDigit == 10) { $checkDigit = 0; } return $checkDigit == (int) $number[8]; } $number = "123456789"; if (validateCompanyRegistrationNumber($number)) { echo "$number is valid."; } else { echo "$number is not valid."; 

} 

xtrabackup - mysql file level backup

 https://www.digitalocean.com/community/tutorials/how-to-create-hot-backups-of-mysql-databases-with-percona-xtrabackup-on-centos-7 

https://www.percona.com/blog/2020/04/10/percona-xtrabackup-backup-and-restore-of-a-single-table-or-database/

large mysql db load

 zr more

mysql connections

show variables like "%max_connections%";show global status  like "%Max_used%";show status like "%thread%"; 

mysql memoty tuning

 https://www.percona.com/blog/2016/05/03/best-practices-for-configuring-optimal-mysql-memory-usage/

mysql memory calculator

 #!/bin/sh# you might want to add some user authentication here

mysql -e "show variables; show status" | awk '  
{
VAR[$1]=$2  
}
END {  
MAX_CONN = VAR["max_connections"]  
MAX_USED_CONN = VAR["Max_used_connections"]  
BASE_MEM=VAR["key_buffer_size"] + VAR["query_cache_size"] + VAR["innodb_buffer_pool_size"] + VAR["innodb_additional_mem_pool_size"] + VAR["innodb_log_buffer_size"]  
MEM_PER_CONN=VAR["read_buffer_size"] + VAR["read_rnd_buffer_size"] + VAR["sort_buffer_size"] + VAR["join_buffer_size"] + VAR["binlog_cache_size"] + VAR["thread_stack"] + VAR["tmp_table_size"]  
MEM_TOTAL_MIN=BASE_MEM + MEM_PER_CONN*MAX_USED_CONN  
MEM_TOTAL_MAX=BASE_MEM + MEM_PER_CONN*MAX_CONN
printf "+------------------------------------------+--------------------+\n"  
printf "| %40s | %15.3f MB |\n", "key_buffer_size", VAR["key_buffer_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "query_cache_size", VAR["query_cache_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "innodb_buffer_pool_size", VAR["innodb_buffer_pool_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "innodb_additional_mem_pool_size", VAR["innodb_additional_mem_pool_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "innodb_log_buffer_size", VAR["innodb_log_buffer_size"]/1048576  
printf "+------------------------------------------+--------------------+\n"  
printf "| %40s | %15.3f MB |\n", "BASE MEMORY", BASE_MEM/1048576  
printf "+------------------------------------------+--------------------+\n"  
printf "| %40s | %15.3f MB |\n", "sort_buffer_size", VAR["sort_buffer_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "read_buffer_size", VAR["read_buffer_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "read_rnd_buffer_size", VAR["read_rnd_buffer_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "join_buffer_size", VAR["join_buffer_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "thread_stack", VAR["thread_stack"]/1048576  
printf "| %40s | %15.3f MB |\n", "binlog_cache_size", VAR["binlog_cache_size"]/1048576  
printf "| %40s | %15.3f MB |\n", "tmp_table_size", VAR["tmp_table_size"]/1048576  
printf "+------------------------------------------+--------------------+\n"  
printf "| %40s | %15.3f MB |\n", "MEMORY PER CONNECTION", MEM_PER_CONN/1048576  
printf "+------------------------------------------+--------------------+\n"  
printf "| %40s | %18d |\n", "Max_used_connections", MAX_USED_CONN  
printf "| %40s | %18d |\n", "max_connections", MAX_CONN  
printf "+------------------------------------------+--------------------+\n"  
printf "| %40s | %15.3f MB |\n", "TOTAL (MIN)", MEM_TOTAL_MIN/1048576  
printf "| %40s | %15.3f MB |\n", "TOTAL (MAX)", MEM_TOTAL_MAX/1048576  
printf "+------------------------------------------+--------------------+\n"  
}'