How to check mail queue in qmail?

# /var/qmail/bin/qmail-qstat 
# nice find /var/qmail/queue/mess/ -type f | xargs grep '^From: '  | awk '{print $2}' | sort | uniq -c | sort -n | tail
# nice -20 find /var/qmail/queue/mess/ -type f |xargs egrep '^From|^To' |sort -k1 |uniq |sort -k2 |uniq -c -f 1 |sort -n |tail

The watch Linux command line tool

This little utility executes a program repeatedly at a set interval and displays its output.


I've been using it with mysqladmin's processlist command like this:

# watch -n 1 /usr/bin/mysqladmin -uroot -pMYPASSWORD  processlist

I 've been using with mysqladmin's processlist command for the Plesk installed server like this:

# watch -n 1 /usr/bin/mysqladmin -uadmin -p`cat /etc/psa/.psa.shadow`  processlist

Note that this does put your password on display at the top of the command window whilst watch is running. If you don't want that, you could write a little bash script instead like this one:

#!/bin/sh

while :
do
sleep 1
clear
mysqladmin -uroot -pMYPASSWORD processlist 
done

Either way, we get a display of the MySQL process list every second in a Terminal window and it becomes very easy to see which processes are causing trouble.

Find heavy processes in Linux

▽ CPU Usage rate descending order

# ps auxw | sort -k3 -nr

▽ Memory Usage rate descending order

# ps auxw | sort -k4 -nr

▽Memory Usage rate descending order

# ps auxww | less | sort -k4 -n

Debian Aptitude

1. aptitude update: Update the local cache of available packages (formerly apt-get update.
2. aptitude upgrade: Upgrade available packages (formerly apt-get upgrade).
3. aptitude dist-upgrade: Upgrade available packages even if it means removing stuff (formerly apt-get dist-upgrade).
4. aptitude install pkgname: Install package (formerly apt-get install).
5. aptitude remove pkgname: Uninstall package (formerly apt-get remove).
6. aptitude purge pkgname: Uninstall package and config files (formerly apt-get --purge remove).
7. aptitude search string: Search for a package with "string" in the name or description (formerly apt-cache search string).
8. aptitude show pkgname: Show detailed of a package (formerly apt-cache show pkgname).
9. aptitude clean: Delete downloaded package files (formerly apt-get clean).
10. aptitude autoclean: Delete only out-of-date package files but keep current ones (formerly apt-get autoclean).
11. aptitude hold pkgname: Fix a package at its current version and don't upgrade it automatically (formerly an obscure echo-to-file command). unhold to remove the hold.

MySQL connection from an external host

MySQL permits the connection from localhost by default. For permitting the connection from an external host, it needs to set up in the following procedure. Add account to the user table of Database mysql.

[root@4a-o01-b3 ~]# mysql -u root -p ※Loging to MySQL by root.
Enter password: ※response password

mysql> select user,host from mysql.user;
+------+--------------------------+
| user | host                     |
+------+--------------------------+
| root | 127.0.0.1                |
| root | example.com              |
| root | localhost                |
+------+--------------------------+



■The items of the above-mentioned setup are as follows.

root@127.0.0.1 - IP Address "127.0.0.1(Namely, a local host)"can be accessed by user root.

root@example.com - HOST "example.com(Here, this is also a local host. )"can be accessed by user root.

root@localhost - localhost "localhost(Namely, a local host)"can be accessed by user root.

Only connection from a localhost can be performed in this stage.
Run following command to permit the connection from an external host. (※Fo example, username "bogati"、The external host who connects"nepal.com"、DB to be used "test" is set up)。


mysql> show databases; ※ Check a list of the existing database.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| test               |
+--------------------+

mysql> grant all privileges on test.* to bogati@"nepal.com" identified by 'password' with grant option;
Query OK, 0 rows affected (1.00 sec)

mysql> select * from user where user="bogati"\G ※ check of executed command.
*************************** 1. row ***************************
Host: nepal.com
User: bogati
Password: *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29

...................................................

■Moreover, to connect from all the hosts, a wild card is specified as follows.

mysql> grant all privileges on test.* to bogati@"%" identified by 'password' with grant option;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from user where user="bogati" && host="%"\G ※ check of executed command.
*************************** 1. row ***************************
Host: %
User: bogati
Password: *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29

...................................................

■To connect from all the hosts of LAN set up as follows.

mysql> grant all privileges on test.* to bogati@"192.168.122.%" identified by 'password' with grant option;
Query OK, 0 rows affected (0.00 sec)

mysql> select * from user where user="bogati" && host="192.168.122.%"\G ※ check of executed command.
*************************** 1. row ***************************
Host: 192.168.122.%
User: bogati
Password: *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29


■To connect from an external host.

After setting up the permission from an external host.
check that whether login is actually possible from an external host or not.
Since it becomes conditions that MySQL is installed in an external host also , when there is no environment, it is necessary to install.

Now connect from nepal.com

[root@nepal.com]# mysql -h example.com -u bogati -p

After the execution of the above-mentioned command, if login is successful, it will be the completion of a setting.


Thanks