Below is command to find out number of connections from each ip to server using netstat , sort, uniq, awk.
netstat -anp |grep 'tcp\|udp' | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n
Here is description of Grep used in this command :: Grep is used for sorting lines which are matching for defined pattern but if you want to sort such lines which are matching two or more different pattern then simply define all patterns in single quote and separate them using \| .
Problem: warning: setlocale: LC_CTYPE: cannot change locale (UTF-8)
run following command in shell
export LC_ALL=”en_US.UTF-8″
1. Create a file named .profile if it doesn’t already exists. Add the following line for that file.
alias ls='ls -G'
This will add higlighting when you use, ls commands to list files and directories, better than looking at black color all the time.
2. Do the following to add highlighting for vi editor.
:~ cd /usr/share/vim/ :~ sudo vim vimrc
Add the following code after the line with ‘set backspace=2′
set ai " auto indenting
set history=100 " keep 100 lines of history
set ruler " show the cursor position
syntax on " syntax highlighting
set hlsearch " highlight the last searched term
filetype plugin on " use the file type plugins
" When editing a file, always jump to the last cursor position
autocmd BufReadPost *
\ if ! exists("g:leave_my_cursor_position_alone") |
\ if line("'\"") > 0 && line ("'\"") <= line("$") |
\ exe "normal g'\"" |
\ endif |
\ endif
Save the file with Esc + :wq. Now your vi editor will show source files with some highlighting as well.
To renew the certificate for server e12postcard.e12labs.com, a server with CAS andHT roles installed:
Get-ExchangeCertificate -domain “e12postcard.e12labs.com” | fl
Note the services the certificate is enabled for (by default: POP, IMAP, IIS, SMTP on CAS + HT servers). Copy the thumbprint of the certificate.
Get a new certificate with a new expiration date:
Get-ExchangeCertificate -thumbprint “C5DD5B60949267AD624618D8492C4C5281FDD10F” | New-ExchangeCertificate
New-ExchangeCertificate -PrivateKeyExportable $true
If the existing certificate is being used as the default SMTP certificate, you will get the following prompt. The default SMTP certificate is used to encrypt SMTP sessions between transport servers in your organization.
Confirm
Overwrite existing default SMTP certificate,
‘C5DD5B60949267AD624618D8492C4C5281FDD10F’ (expires 8/22/2008 7:20:34 AM), with certificate ’3DA55740509DBA19D1A43A9C7161ED2D0B3B9E3E’ (expires 1/28/2009 7:37:31 AM)?
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help
(default is “Y”):
Type y to continue. A new certificate is generated.
Thumbprint Services Subject
———- ——– ——-
3DA55740509DBA19D1A43A9C7161ED2D0B3B9E3E ….. CN=E12Postcard
The new certificate is generated and enabled.
The Following command drops all databases in the mysql dbms except mysql, information_schema,test and OLD db’s.
The command is pretty handy when one needs to drop all the databases in one go:
# mysql -uroot -p -e "show databases" | grep -v Database | grep -v mysql| grep -v information_schema| grep -v test | grep -v OLD |gawk '{print "drop database " $1 ";select sleep(0.1);"}' | mysql -uroot -ppassword
What this does is
- connect to a mysql dbms server and execute the command for showing all databases
- Omit lines that match “Database” while printing.
- Omit lines with mysql,infomation_schema and test.
- use gawk to print out the words “drop database” followed by the daabase name (which is in $1) and then a semicolon. Call sleep command.
- pipe all of above back to the mysql dbms to drop all those databases
Also,
mysql -uroot -pxxxxx -e "show databases" | grep -v Database | grep -v mysql | grep -v information_schema| grep -v test | grep -v OLD | gawk '{print "drop database " $1";select sleep(0.1);"}' > droppeddatabases.sql
$ x=a:b:c
$ echo ${x%:*}
a:b
$ echo ${x#*:}
b:c
The bit after the % or # is more like a shell glob than a regular expression, in case you want to get fancy there.
$ echo ${x%%:*}
Resetting PRAM and NVRAM
- Shut down the computer.
- Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
- Turn on the computer.
- Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
- Hold the keys down until the computer restarts and you hear the startup sound for the second time.
- Release the keys.
Your computer’s PRAM and the NVRAM are reset to the default values. The clock settings may be reset to a default date on some models.
Contents of PRAM
Some Macintosh computers may not have all the settings described below. For Mac OS X information, refer to Mac OS X: What’s Stored in PRAM?
- Status of AppleTalk
- Serial Port Configuration and Port definition
- Alarm clock setting
- Application font
- Serial printer location
- Autokey rate
- Autokey delay
- Speaker volume
- Attention (beep) sound
- Double-click time
- Caret blink time (insertion point rate)
- Mouse scaling (mouse speed)
- Startup disk
- Menu blink count
- Monitor depth
- 32-bit addressing
- Virtual memory
- RAM disk
- Disk cache
Note: Portable computers that have a battery you should not remove on your own include MacBook Pro (Early 2009) and later, all models of MacBook Air, and MacBook (Late 2009).
- Shut down the computer.
- Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
- On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
- Release all the keys and the power button at the same time.
- Press the power button to turn on the computer.
Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.
Additional Information
The System Management Controller (SMC) is responsible for many low-level functions on Intel-based Macs. These functions include:
- Responding to presses of the power button
- Responding to display lid opening and closing on portable Macs
- Battery management
- Thermal management
- The SMS (Sudden Motion Sensor)
- Ambient light sensing
- Keyboard backlighting
- Status Indicator Light (SIL) management
- Battery status indicator lights
- Selecting an external (instead of internal) video source for some iMac displays
Command-line Tools:
The date command can be used as follows to display the time and date:
$ date
Fri Mar 28 16:01:50 CST 2003
To see UTC/GMT, you can do this:
$ date –utc
Fri Mar 28 08:04:32 UTC 2003
The date command also can be used to set the time and date. To set the time manually, do this:
# date -s “16:15:00″
Fri Mar 28 16:15:00 CST 2003
If you also need to adjust the date, and not just the time, you can do it like this:
# date -s “16:55:30 July 7, 1986″
Mon Jul 7 16:55:30 PDT 1986
There is also another way to set the date and time, which is not very pretty:
# date 033121422003.55
Mon Mar 31 21:42:55 PST 2003
The above command does not use the -s option, and the fields are arranged like this: MMDDhhmmCCYY.ss
where MM = month, DD = day, hh = hour, mm = minute, CCYY = 4 digit year, and ss = seconds.
Please note that setting the clock with the date command must be done as root. This is a “savage” way to adjust the time. It adjusts the Linux kernel system time.
There is also a hardware clock (CMOS clock). You can look at the current hardware clock time with:
hwclock –show
I always keep my hardware clocks set to UTC/GMT. This maintains my clocks uniformly without any worries about “Daylight Savings Time”. This is important, because when you set the hardware clock from the system clock (kept by the Linux kernel), you need to know if this is the case. To set the hardware clock from the system clock, leaving the hardware clock in UTC, enter the following:
# hwclock –systohc –utc
# hwclock –show
Fri 28 Mar 2003 04:23:52 PM CST -0.864036 seconds
Another interesting item is that the Linux system clock stores time in seconds since midnight on January 1st, 1970 (UTC). This is called UNIX time. Unfortunately, because this is a 32-bit value, there is a year-2038 problem. Hopefully, everyone will have moved to 64-bit architectures by then. In order to see the UNIX time, you can use the following command:
date +%s
There are many useful formatting options for the date command. See the date manpage for details.
Of course, there is another useful tool available related to date and time: cal
$ cal -3
February 2003 March 2003 April 2003
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 1 1 2 3 4 5
2 3 4 5 6 7 8 2 3 4 5 6 7 8 6 7 8 9 10 11 12
9 10 11 12 13 14 15 9 10 11 12 13 14 15 13 14 15 16 17 18 19
16 17 18 19 20 21 22 16 17 18 19 20 21 22 20 21 22 23 24 25 26
23 24 25 26 27 28 23 24 25 26 27 28 29 27 28 29 30
30 31
You can also specify “cal -y” for the entire year, “cal” by itself for the current month, or “cal 12 2005” to see the calendar for December, 2005.
Time Zone Configuration:
Background – The Earth is divided into time zones that are 15 degrees of longitude each, for this corresponds to the amount of angular distance the Sun appears to travel in 1 hour. 0 degrees longitude runs through the Royal Observatory in Greenwich, England. This is the origin of Greenwich Mean Time, or GMT. For all practical purposes, GMT and UTC are the same. To complicate matters, some countries observe Daylight Savings Time (DST), while others do not. Even within some countries, some states or districts do not observe DST while the rest of the country does! DST can also begin and end on different days in different countries! What a mess…
There are several files and directories that are used for time zones, and several tools:
/etc/sysconfig/clock - this is a short text file that defines the timezone, whether or not the hardware clock is using UTC, and an ARC option that is only relevant to DEC systems.
/etc/localtime - this is a symbolic link to the appropriate time zone file in /usr/share/zoneinfo
/usr/share/zoneinfo - this directory contains the time zone files that were compiled by zic. These are binary files and cannot be viewed with a text viewer. The files contain information such as rules about DST. They allow the kernel to convert UTC UNIX time into appropriate local dates and times.
/etc/rc.d/rc.sysinit - This script runs once, at boot time. A section of this script sets the system time from the hardware clock and applies the local time zone information.
/etc/init.d/halt - This script runs during system shutdown. A section of this script synchronizes the hardware clock from the system clock.
/etc/adjtime – This file is used by the adjtimex function, which can smoothly adjust system time while the system runs. settimeofday is a related function.
redhat-config-date or dateconfig - These commands start the Red Hat date/time/time zone configuration GUI. Both commands failed to change the timezone in two different stock Red Hat 8.0 systems. They also failed to create a working ntp.conf file for the NTP server. The timezone problem went away after upgrading from the installed RPM, redhat-config-date-1.5.2-10, to a newer RPM from a Red Hat beta release, redhat-config-date-1.5.9-6.
zic - (The time zone compiler) Zic creates the time conversion information files.
zdump - This utility prints the current time and date in the specified time zone. Example:
# zdump Japan
Japan Sat Mar 29 00:47:57 2003 JST
# zdump Iceland
Iceland Fri Mar 28 15:48:02 2003 GMT
In order to manually change the timezone, you can edit the /etc/sysconfig/clock file and then make a new soft link to /etc/localtime. Here is an example of changing the timezone manually to “America/Denver”:
1. Select the appropriate time zone from the /usr/share/zoneinfo directory. Time zone names are relative to that directory. In this case, we will select “America/Denver”
2. Edit the /etc/sysconfig/clock text file so that it looks like this:
ZONE=”America/Denver”
UTC=true
ARC=false
Of course, this assumes that your hardware clock is running UTC time…
3. Delete the following file: /etc/localtime
4. Create a new soft link for /etc/localtime. Here is an example of step 3 and step 4:
# cd /etc
# ls -al localtime
lrwxrwxrwx 1 root root 39 Mar 28 07:00 localtime -> /usr/share/zoneinfo/America/Los_Angeles
# rm /etc/localtime
# ln -s /usr/share/zoneinfo/America/Denver /etc/localtime
# ls -al localtime
lrwxrwxrwx 1 root root 34 Mar 28 08:59 localtime -> /usr/share/zoneinfo/America/Denver
# date
Fri Mar 28 09:00:04 MST 2003
NTP Configuration and Usage:
Background – Network Time Protocol (NTP) allows computers, servers, and network devices to synchronize their internal clock systems to an external reference source. In some cases, the reference source can be an atomic clock or GPS receiver. This is useful for a number of reasons. If you would like to automatically keep the time on your Linux system synchronized to standard world times, you have two built-in tools to do this:
ntpdate and ntpd (NTP Daemon)
ntpdate:
ntpdate was written by David L. Mills at the University of Delaware. For details on Dr. Mills, enter this:
$ finger David.L.Mills@udel.edu
ntpdate allows you to view or set system time from one or more NTP servers. The first thing you need to do is find a time server you can query. Here is a list of public time servers, or you can use one of the following:
clock.redhat.com
clock2.redhat.com
ns1.tuxfamily.org
time.nist.gov
For example, if you only want to query an NTP server and make sure that you can reach it, use the following command:
# ntpdate -q clock2.redhat.com
server 66.187.224.4, stratum 1, offset -0.067532, delay 0.38452
28 Mar 18:14:20 ntpdate[10724]: adjust time server 66.187.224.4 offset -0.067532 sec
Note that some firewall systems do not allow NTP traffic. NTP uses UDP port 123. If you would like to query more than one server and set your system clock with the result, use the following:
# ntpdate clock2.redhat.com clock.redhat.com
28 Mar 18:20:59 ntpdate[10754]: adjust time server 66.187.233.4 offset -0.043222 sec
You can add the -v flag for verbose output.
This command is very similar to the rdate command. The ntpdate command can be used in startup scripts or cron jobs to automatically set the system time without running a dedicated server process. You will definitely want to try to retrieve the time from an NTP server with ntpdate before setting up your own NTP server. This will ensure that (a) you have connectivity (b) your firewall does not block NTP. Another thing to note about the ntpdatecommand is that it will not work in update mode if you are running a local NTP server process. It will work in query mode.
NTP Server:
The NTP server (ntpd) can be setup to run continuously. This will keep the system clock synchronized. You will also be able to server NTP clients on your LAN, if you wish. I had problems with the Red Hat configuration GUInot setting the NTP server up correctly.
The configuration file is /etc/ntp.conf, and there is also an /etc/ntp directory which contains keys and the drift file. I will show you a working configuration file, with comments:
# Prohibit general access to this service.
restrict default ignore
# Permit all access over the loopback interface. This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
# — CLIENT NETWORK ——-
# Permit systems on this network to synchronize with this
# time service. Do not permit those systems to modify the
# configuration of this service. Also, do not use those
# systems as peers for synchronization.
# This is my internal LAN network address
restrict 192.168.212.0 mask 255.255.255.0 notrust nomodify notrap
# — OUR TIMESERVERS —–
# or remove the default restrict line
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
# The statements below limit what the servers can do to your server
# I am using IP instead of DNS name because the “restrict” construct
# requires IP addresses
restrict 66.187.224.4 mask 255.255.255.255 nomodify notrap noquery
restrict 80.67.177.2 mask 255.255.255.255 nomodify notrap noquery
# The server listed below is clock2.redhat.com
server 66.187.224.4
# The server listed below is ns1.tuxfamily.org
server 80.67.177.2
# — NTP MULTICASTCLIENT —
#multicastclient # listen on default 224.0.1.1
# restrict 224.0.1.1 mask 255.255.255.255 notrust nomodify notrap
# restrict 192.168.1.0 mask 255.255.255.0 notrust nomodify notrap
# I don’t want to use multicast for my NTP server
# — GENERAL CONFIGURATION —
#
# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available. The
# default stratum is usually 3, but in this case we elect to use stratum
# 0. Since the server line does not have the prefer keyword, this driver
# is never used for synchronization, unless no other other
# synchronization source is available. In case the local host is
# controlled by some external source, such as an external oscillator or
# another protocol, the prefer keyword would cause the local host to
# disregard all other synchronization sources, unless the kernel
# modifications are in use and declare an unsynchronized condition.
#
# If you un-comment the two statements below, you could run an NTP server
# off of your local (and inaccurate) system clock.
#restrict 127.127.1.0
#server 127.127.1.0
fudge 127.127.1.0 stratum 10
#
# Drift file. Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()’ing
# it to the file.
#
driftfile /etc/ntp/drift
broadcastdelay 0.008
#
# Authentication delay. If you use, or plan to use someday, the
# authentication facility you should make the programs in the auth_stuff
# directory and figure out what this number should be on your machine.
#
# I am not using any authentication for this simple setup.
authenticate no
#
# Keys file. If you want to diddle your server at run time, make a
# keys file (mode 600 for sure) and define the key number to be
# used for making requests.
#
# PLEASE DO NOT USE THE DEFAULT VALUES HERE. Pick your own, or remote
# systems might be able to reset your clock at will. Note also that
# ntpd is started with a -A flag, disabling authentication, that
# will have to be removed as well.
#
keys /etc/ntp/keys
After you install this new version of the config file, you can start the service with /etc/init.d/ntpd start
To monitor the service, you can run the following command: ntpdc -p or ntpdc -p -n
If you are really impatient, you can use this command to watch the system until it synchronizes: watch nptdc -p -n
The ntpdc command can be run interactively as well. There are a number of informative ntpdc commands, such as iostats, sysstats, and peers.
When enough time has gone by, one of the servers will have an * placed in front of it to tell you that your system is synchronized to it. The lower the stratum number, the more accurate the server.
If you want to have the NTP server start up automatically, you can use the checkconfig command as follows:
# chkconfig –level 345 ntpd on
# chkconfig –level 0126 ntpd off
# chkconfig –list | grep ntpd
ntpd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
To see that your NTP server is listening on UDP port 123, use the following command: netstat -tuna
Please note that the NTP server makes NTP queries from a UDP source port of 123. Some firewalls will not allow this, even if ntpdate worked (ntpdate uses a source port > 1023.)
You can also use the ntpq utility, and the ntptrace utility for additional diagnostic support. For complete documentation on setting up and using NTP servers, see www.ntp.org.
While running a MySQL Master replication to a slave location, you might notice that the binlogs are stored on the filesystem and not cleaned up regularly. There are several ways to deal with this, I found this to be a nice approach;
Here you have a list of binlog known to the system
mysql> show binary logs; +------------------+-----------+ | Log_name | File_size | +------------------+-----------+ | mysql-bin.000001 | 602721 | | mysql-bin.000002 | 338 | | mysql-bin.000003 | 47207 | | mysql-bin.000004 | 56661 | | mysql-bin.000005 | 96460 | | mysql-bin.000006 | 117 | | mysql-bin.000007 | 4486 | | mysql-bin.000008 | 119368 | +------------------+-----------+ 8 rows in set (0.00 sec)
To Clean these up by hand you could execute :
mysql>PURGE BINARY LOGS BEFORE DATE_SUB( NOW( ), INTERVAL 0 DAY);
To Clean these up by hand if older then 7 Day’s
mysql>PURGE BINARY LOGS BEFORE DATE_SUB( NOW( ), INTERVAL 7 DAY);
Result would be :
mysql> show binary logs; +------------------+-----------+ | Log_name | File_size | +------------------+-----------+ | mysql-bin.000008 | 244883 | +------------------+-----------+ 1 row in set (0.00 sec)
Find here the CRON job created to delete binary logs older the 7 days on every sunday at 23:00.
# MySQL Clean-up the BINARY LOGs 00 23 * * 0 /usr/bin/mysql -e "PURGE BINARY LOGS BEFORE DATE_SUB( NOW( ), INTERVAL 7 DAY);
1. Insert CD/DVD source
2. Fire up a Terminal, you can then determine the device that is you CD/DVD drive using the following command:
$ drutil status
Vendor Product Rev
MATSHITA DVD-R UJ-835E GAND
Type: DVD-ROM Name: /dev/disk1
Cur Write: 8x DVD Sessions: 1
Max Write: 8x DVD Tracks: 1
Overwritable: 00:00:00 blocks: 0 / 0.00MB / 0.00MiB
Space Free: 00:00:00 blocks: 0 / 0.00MB / 0.00MiB
Space Used: 364:08:27 blocks: 1638627 / 3.36GB / 3.13GiB
Writability:
Book Type: DVD-ROM
3. Umount the disk with the following command:
$ diskutil unmountDisk /dev/disk1 Disk /dev/disk1 unmounted
4. Create the ISO file with the dd utility (may take some time):
$ dd if=/dev/disk1 of=file.iso bs=2048
5. Test the ISO image by mounting the new file (or open with Finder):
$ hdid file.iso
6. The ISO image can then be burnt to a blank CD/DVD.
