mysql:3306
sqlserver:1433
Oracle:1521
Windows shared disk mount:
mount -t cifs -o username=byf,password=byf //192.168.1.100/share /mnt/server
ls -lR /var/log/ | grep "-" | wc -l -------> count the number of files in the directory
ls -lR /var/log/ | grep "d" | wc -l -------> count the number of directories in the directory
Count the number of connections per IP on the local server:
netstat -n | awk '/^tcp/ {print $5}' | awk -F : '{print $1}' | sort | uniq -c | sort -rn
Oracle DB：
This study uses oracle 10g. The version is 10.2.0.1.0
Scripts can be imported via PLSQL Developer. The command format is @script path.eg: @d:/abc.sql
DML: data manipulation language (select, insert, update, delete)
DDL: Data Definition language data definition language (mainly used to change table structure, data types, etc. create, alter, drop)
DCL: Data Control language Data Control Language (statements to set or change database users or roles. grant, deny, revoke)
Related commands:
desc tablename: View table information
||: used for connectors between columns eg: select id || ',' || name from table
distinct: deduplicate select distinct dep_id from table_hr
like: fuzzy query where name like '%a%' or '__a%' ('%\_%' escape \, where escape defines \ as an escape character)
Empty: is null Not empty: is not null
Sort: order by [asc|desc] positive order|reverse order order by id asc,salary desc
to_char: conversion function
(not)between: between two values, including boundaries
function:
lower: lowercase upper: uppercase initcap: first letter uppercase
concat('hello','world') result: helloworld function: connect
substr('helloworld','1,5) Result: hello Function: Display the letters from 1 to 5
length('hello') Result: 5 Function: Calculate the length of the string
lpad(salary,10,'*') Same as above, right padding
replace('abcd','b','m') amcd replace b in abcd with m
TRIM('h' from hellworld) ellworld remove the ending h
Numeric function:
round(number, digit) rounding
trunc(number) truncates regardless of the number of digits after the decimal point
mod(number/number) remainder
month_between(date, date) The number of months between two dates
add_months(sysdate,2) adds a number of months (2 months) to the specified date
next_day (date, day of the week): the latest date corresponding to the next day of the week of the specified date
last_day: the last day of the month