Unix  Basic date format

$date “+<Parameter><seprator><Parameter><seprator><Parameter>

Where Parameters  is  any one or more Parameter from the list below and separator is a any field separator like hyphen( – ) , slash \ , colon :   and it is optional.

Unix Date Format Examples

lets get the parameter for year , month and date and produce a hyphen separated date format

$date “+%Y-%m-%d”

2010-02-10

%Y is keyword for four digit year
%m is keyword for two digit month
%d is keyword for two digit date
Hyphen is separator here .

If you change the separator here to slash the format would look like

$date “+%Y/%m/%d”
2010/02/10

You can switch date keyword anyway you want , if you need month first and year last ,

$date “+%m-%d-%Y”
02-10-2010

Weekdays

You can have additional weekday information in your date with %A as

$date “+%m-%d-%Y %A”
02-10-2010 Wednesday

or

$date “+%A %m-%d-%Y”
Wednesday 02-10-2010

These are options you can select for weekday

%a weekday, abbreviated Wed
%A weekday, full Wednesday
%d day of the month (dd), zero padded 10
%e day of the month (dd) 10
%j day of year, zero padded 000-366
%u day of week starting with Monday (1), i.e. mtwtfss 3
%w day of week starting with Sunday (0), i.e. smtwtfs 3

Month

You can have additional month information in your date with %B as

$date “+%m-%d-%Y %B”
02-10-2010 Februrary

or

$date “+%B %m-%d-%Y”
February 02-10-2010

These are options you can select for month

%m mm month as two digits
%b Mon, locale’s abbreviated Feb
%B locale’s full month, variable length February

Year

You can have additional year information as two digit or four digit with %y or %Y as

$date “+%m-%d-%y ”
02-10-10

or

$date “+%m-%d-%Y ”
02-10-2010

These are options you can select for year

%y yy two digit year 00–99
%Y ccyy year 2010

Additional date format parameters which can be used :

Week

%U week number Sunday as first day of week 01–53
%W week number Monday as first day of week 01–53
%V week of the year 01–53

Century

%C cc century 00–99

Date

%D mm/dd/yy 02/10/10
%x locale’s date representation (mm/dd/yy) 02/10/2010
%F %Y-%m-%d 2010-02-10

Date and Time time stamp

%c locale’s date and time Wed Feb 10 10:02:33 PST 2010

Time function

Time function is simple to use and date command is used to format & display time as well . You can use date and time parameters to format your date time stamp as per your requirment

A simple time stamp with date can be generated as :

$date “+%c”
%c locale’s date and time Sat Nov 04 12:02:33 EST 1989

Date function have some preformated time stamps to make things easier

Example :

$date “+%r”
05:28:55 PM

More preformated options :

%R hours, minutes (24 hour clock) hh:mm e.g. 17:28
%T hours, minutes, seconds (24-hour clock) 17:28:55
%X locale’s time representation (%H:%M:%S) 05:28:55 PM

Custom time format

Examples

Time stamp with 12 hr clock

$date “+%l:%M:%S
5:22:45

Time stamp with 24 hr clock

$date “+%H:%M:%S”
20:22:45

Time stamp with AM/PM

$date “+%l:%M:%S %p”
5:22:45  PM

Additional date time parameters :

Hours
%l (Lowercase L) hour (12 hour clock) 8
%I (Uppercase I) hour (12 hour clock) zero padded 08
%k hour (24 hour clock) 20
%H hour (24 hour clock) zero padded 20
%p locale’s upper case AM or PM (blank in many locales) PM
%P locale’s lower case am or pm (really!) pm

Minutes
%M MM minutes 28

Seconds
%s seconds since 00:00:00 1970-01-01 UTC (Unix epoch) 1265833735
%S SS second 00–60
%N nanoseconds 000000000–999999999

Time zone
%z -zzzz RFC-822 style numeric timezone -0500
%Z time zone (e.g., EDT) nothing if no time zone is determinable EST

SE, HVD, LVD SCSI interfaces – Single Ended interface drives each signal line against ground & is susceptible to noise and has short length.
High Voltage Differential interface drives two lines for each SCSI signal. One line is the inverse of the other line and the SCSI signal is the difference and hence term differential.
Low Voltage Differential uses 3.3 volt logic which is 5V in HVD. Maximum cable lenth supported are from 1.5 to 6 meter in SE , 25 meters in HVD & 12 Meters in LVD.
A multimode LVD device will automatically switch between LVD and single-ended operation by detecting whether the other devices on the chain are running in SE or LVD mode. SE & LVD are not electrically compatible to HVD due to voltage difference.

CIDR : Classless Inter-Domain Routing – the notation often used instead of writing the subnet mask along with ip-address . It has network prefix at the end of a address as / number of network bits.This means that the IP address 192.200.20.10 with the subnet mask 255.255.255.0 can also be expressed as 192.200.20.10/24. The /24 indicates the network prefix length, which is equal to the number of continuous binary one-bits in the subnet mask (11111111.11111111.11111111.000000). Zeros are for addressing the hosts on this network.

Priority Paging : Priority paging parameter in pre Solaris 8 versions allows file system cache in the memory to be paged out first leaving application and data in the memory . Free memory is used for caching file system in Pre Solaris 8 versions and paging in such cases sometimes led to paging out of application & data , making application experience a page-in page-out time delay.Solaris 8 keeps file cache isolated so it is not required there. This can be enabled in pre solaris 8 versions by adding line “set priority paging=1″ in /etc/system. Remove this line if upgrading from Solaris 7 to 8 & retaining old /etc/system file.

FSSTABLE : File System Stable state flag. The file system is (or was) mounted but has not changed since the last checkpoint (sync or fsflush) that normally occurs every 30 seconds. The kernel periodically checks if a file system is idle and, if so, flushes the information in the superblock back to the disk and marks it as FSSTABLE. If the system crashes, the file system structure is stable, but users might lose a small amount of data. File systems that are marked as FSSTABLE can skip the checking before mounting. The mount command will not mount a file system for read and write access if the file system state is not FSCLEAN, FSSTABLE, or FSLOG in case of logging file system

umask - is the filter which determines the default file and directory permissions at the time of their creation . It is represented by 3 octal values representing permissions to be denied by default .First value is for user ,second for group and third for others permission .Default is 022 and set in /etc/profile .Current value can be seen by typing umask at command prompt

Dynamic System Domains – the ability to create multiple (Solaris) systems within a single Enterprise 10000 chassis. The components which form a domain (system boards, CPU, memory and i/o) are electrically isolated from other domains to provide the protection between applications running in different domains. The hardware within domains can be reconfigured under software control to meet fluctuating demands of applications running within the domains of an Enterprise 10000

Following are the different types of Unix shells ,

B shell , /bin/sh – This is the default Unix shell for many Unix operating systems .
Bourne shell was written by S. R. Bourne and its more emphasis is to use it as a scripting language rather than an interactive shell .
Some of the features are :
Provided support for environment variables using parameters and exportable variables.
Redirection of program output and error .
Command substitution using back quotes: `command`.
embed a file/commands using input redirector <<
“for ~ do ~ done” loops
“case ~ in ~ esac” for selecting and responding to a data value .

C-shell /bin/csh was designed to provide the interactive features lacking in b shell such as job control and aliasing .

K shell /bin/ksh – was created by David Korn and has features of both B shell and C shell along with some additional features .

Bash – the Bourne again shell was developed by GNU project .It is based on B shell language and has features of C and K shells.

tcsh is the default shell of FreeBSD and its descendants. Essentially it is C shell with programmable command line completion, command-line editing, and a few other features.

Zsh is a shell designed for interactive use and it has many of the useful features of bash, ksh, and tcsh along with many new features.

Unix Shells configuration files :

b shell
—————————————————–

shell prompt : $
executable file : /bin/sh

Read on interactive/non interactive login to bash
/etc/profile
~/.profile

bash shell
—————————————————–

shell prompt : $
executable file : /bin/bash

Read on interactive/non interactive login to bash
/etc/profile
~/.profile
~/.bash_profile
~/.bash_login

Always read on invoking bash
~/.bashrc

/etc/profile login login login
~/.profile login login

csh shell
——————————————————

shell prompt : %
executable file : /bin/csh

Read on csh shell invocation .
/etc/csh.cshrc
~/.cshrc

Read on interactive/non interactive login to tcsh shell
/etc/.login
~/.login
~/.logout
/etc/csh.login

ksh
—————————————————–

shell prompt : $
executable file : /bin/ksh

Read on interactive/non interactive login to bash
/etc/profile
~/.profile

tcsh shell
——————————————————

shell prompt : &
executable file : /bin/tcsh

Read on tcsh shell invocation .
~/.tcshrc
/etc/csh.cshrc
~/.cshrc

Read on interactive/non interactive login to tcsh shell
/etc/.login
~/.login
~/.logout
/etc/csh.login

zsh
—————————————————–

shell prompt : $
executable file : zsh

Configuration files :

Always read on invoking zsh
~/.zshenv always
/etc/zshenv always

only read on interactive login to zsh.
~/.zshrc
/etc/zshrc

Read on interactive/non interactive login to zsh
/etc/zprofile login
/etc/zlogin login
/etc/zlogout login
/.zprofile login
~/.zlogin login
~/.zlogout login

Unix Dir Structure – Next

Requirements:
In order to work correctly the vi need  correct terminal type (TERM) setting  .The TERM setting depends on the   type of terminal you have . Commonly used TERM types are vt100 , vt220 and ansi .  In most cases vt100 will  work  fine . In case  vi is not able to understand the TERM you have given, it starts in open mode   giving you a line by line display .
Generally TERM is taken from .profile or  /etc/profile  but can be set at the command line as :
$TERM=vt100
$export TERM

echo $TERM will display the current TERM set.

Create new file or  Open existing file in vi
vi without any file name will open a   new file where you can enter the text and edit but while coming out you will  be asked to enter a valid file name to save the text.  vi with a  file name as argument will  open that file for editing  if the file already exists it opens it  otherwise it creates a new file by the argument.
Example :  $vi  testfile
Creates or opens the existing file called testfile

Modes in vi

vi operates in following  two modes :
i. ) Command Mode : After a file is opened it is opened  in command
mode ,that is , input from the keyboard will be treated as vi commands
and you will not see the words you are typing on the screen .

ii.) Insert Mode: To enter the text you have to put vi in insert  by pressing ‘i’ or ‘a’  after  which you can add the text and whatever is being type will be seen on the  screen. . To switch between these mode Esc key is used .   Esc i
(text mode)  Esc (command mode)

Saving  & Exiting  vi editor
You can exit vi in different ways :

1.) Quit without saving : If you don’t  want to save the work :q  will take you out without saving  your editing in vi.
2.) Write & quit : . Simple :w saves the current file but don’t exit. For save and quit  :wq is  used in vi.
3.) Forced Quite : An ! (Exclamation  sign at the end of  exit commands ( :q! , :wq! )  causes a forced  quit from vi  after ignoring editing (for :q!)  or writing (for :wq!)  all the change

The idea of this article is to introduce you with the procedure and sequence of event Solaris installation to build enough confidence to finish the installation on your own.

Table of contents
1. Before you begin
2. Getting Started
3. Starting the installation
4. OS distributions & disk configuration
5. After Installation
6. Next Steps

1. Before you begin
For Solaris installation on standalone Sun machine you need the following besides sun cpu :

A) Sun Monitor and Sun Keyboard
OR
For carrying the installation through the serial port A of Sun (ttya)
Dumb Terminal or PC with serial port communication software like HyperTerminal
AND
A null modem cable ( Pin 2 & 3 crossed 5 common ground in 9 Pin to 9 pin ; Pin 7 is common ground in 25 Pin connector ) connecting sun’s serial port A with PC serial port.

B) You will also require a IP address, netmask and a host name for your system.

2. Getting Started

Installation starts at OK> prompt & you can get to ok> using any of the following method :

A. by pressing Stop A key sequence on a Sun Keyboard.
B. typing #init 0 if your system boots up directly .
C. Pressing ctrl-break or shift-break on a pc keyboard if using pc as
console through serial port.
D. If auto-boot feature is enabled system directly boots up
and gives you a # prompt .You can disable auto-boot so next time it
stays at ok prompt for starting installation.
#/usr/platform/sun4u/bin/eeprom auto-boot?=false
reboot the system.

3. Starting the installation
Insert the installation media – OS CD in CD drive and type boot cdrom at ok> prompt .
Ok>boot cdrom

The first phase begins with system identification and gathers information about the system from the the user .System starts booting up and after initialization it asks for language and locale also terminal type in case of PC/terminal

Select your locale and DEC VT100 terminal type for terminal selection
Further installation through the terminal require response to the
selections through ESC and function keys and space bar which are
mentioned on the installation screen.

On the next screens, you are to identify the system as networked or non-networked, and set the default time zone and date/time. After this following host information is required :

A) A host name for the system
B) Whether the system is networked if yes you will have to
provide the IP address & netmask of this machine.

Next you will be asked to select the name services
Name services

[    ]                      NIS+
[    ]                      NIS
[    ]                      DNS
[X ]                        None

Select the service if you have complete details like domain names etc or select none to configure after installation.

You have to select a distribution type from among the choices choices

4. OS distribution & Disk configuration
After identification is complete the installation process proceeds on to the OS and disk configuration and need your input for these settings. Selection depends on role of your machine

Typical space requirement for Solaris 7 is given here.

[   ] Entire Distribution plus OEM support 64-bit 1242.00 MB (F4 to Customize
[X] Entire Distribution 64-bit .....…...….1215.00 MB
[   ] Developer System Support 64-bit.... 1154.00 MB
[   ] End User System Support 64-bit .….. 765.00 MB
[   ] Core System Support .............. .334.00 MB

* Entire distribution with OEM has all software with some third party software
* Entire distribution has all software without third party software .
* Developer system has run time libraries for C software etc.
* End user has X windows and CDE environment .
* Core system is without X windows softwares etc.

If you are not sure select entire distribution.

You will be presented with choice to select the boot disk among the disks present in the system ,unless you have reasons select the c0t0d0 at boot disk.

[ X ] c0t0d0 (17269 MB) boot disk 17269 MB

[ ] c0t1d0 (17269 MB) 17269 MB

overlap partition represents entire disk and is slice s2 of the disk.
If any of the disk contain a preexisting partition you will be given a choice to preserve the partition .
Next the current layout is given ( if existing ) and you are asked to select between Automatic and Custom layout of disk partitions.

* Automatic layout make a single partition of entire boot disk .
* Customize option gives and option to create the partitions and select the sizes .

Things to keep in mind while doing interactive or custom installation
- Additional space is required in /var & /home if server is to handle mail and printing as mail and print files are formed in /var & if the user home directories are to be located on /home partition

A sample partition table may look like following .

File system/Mount point Disk/Slice Size
---------------------------------------

/           c0t0d0s0       300 MB

swap        c0t0d0s1       2000 MB

overlap     c0t0d0s2       17269 MB

/usr        c0t0d0s3       2000 MB

/opt        c0t0d0s4       1000 MB

/var        c0t0d0s5       1000 MB

- The swap partition size depends on the size of RAM in the system if you are not sure of its size keep it double the RAM or more than RAM in the system.

- If you are not sure of individual partition sizes of / , /usr /opt & /var make one partition as / and keep its size sufficiently higher than the distribution size you have selected in earlier steps . Always keep in mind the future software that you might have to install like compilers applications etc and log files that will be generated and accumulate in /var directory or partition.

After you have specified the partition sizes it gives summary and error if any

Installation Option: Initial

Boot Device:            c0t0d0s0
Client Services:        None
Software: Solaris 2.7, Entire Distribution

File System and Disk Layout:
/          c0t0d0s0     300 MB
swap       c0t0d0s1     2000 MB
/usr       c0t0d0s3     2000 MB
/opt       c0t0d0s4     1000 MB
/var       c0t0d0s5     1000 MB

one more question is asked about rebooting

[X] Auto Reboot
[  ] Manual Reboot

Afterwards it starts configuring disk making partitions and installing software indicating the progress in a table .

MBytes Installed: 700.66

MBytes Remaining: 0.00

Installing:
|    |     |     |     |     |

0   20    40    60    80    100

After the installation is complete it customizes system files , devices ,logs , installs patches which are there in OS CD for that release. You can install recommended latest patches later

System then reboots or ask you to reboot depending upon the choice selected earlier .

5. After Installation
After rebooting it asks for new root passed and comes to console prompt where you can login as root install patches ,additional software , make user etc. etc.

cron is a unix, solaris utility that allows tasks to be automatically run in the background at regular intervals by the cron daemon. These tasks are often termed as cron jobs in unix , solaris.  Crontab (CRON TABle) is a file which contains the schedule of cron entries to be run and at specified times.

This document covers following aspects of Unix cron jobs
1. Crontab Restrictions
2. Crontab Commands
3. Crontab file – syntax
4. Crontab Example
5. Crontab Environment
6. Disable Email
7. Generate log file for crontab activity

1. Crontab Restrictions
You can execute crontab if your name appears in the file /usr/lib/cron/cron.allow. If that file does not exist, you can use
crontab if your name does not appear in the file /usr/lib/cron/cron.deny.
If only cron.deny exists and is empty, all users can use crontab. If neither file exists, only the root user can use crontab. The allow/deny files consist of one user name per line.

2. Crontab Commands

export EDITOR=vi ;to specify a editor to open crontab file.

crontab -e    Edit your crontab file, or create one if it doesn’t already exist.
crontab -l      Display your crontab file.
crontab -r      Remove your crontab file.
crontab -v      Display the last time you edited your crontab file. (This option is only available on a few systems.)

3. Crontab file
Crontab syntax :
A crontab file has five fields for specifying day , date and time followed by the command to be run at that interval.

*     *     *   *    *        command to be executed
-     -     -   -    -
|     |     |   |    |
|     |     |   |    +----- day of week (0 - 6) (Sunday=0)
|     |     |   +------- month (1 - 12)
|     |     +--------- day of        month (1 - 31)
|     +----------- hour (0 - 23)
+------------- min (0 - 59)

* in the value field above means all legal values as in braces for that column.
The value column can have a * or a list of elements separated by commas. An element is either a number in the ranges shown above or two numbers in the range separated by a hyphen (meaning an inclusive range).
Notes
A. ) Repeat pattern like /2 for every 2 minutes or /10 for every 10 minutes is not supported by all operating systems. If you try to use it and crontab complains it is probably not supported.

B.) The specification of days can be made in two fields: month day and weekday. If both are specified in an entry, they are cumulative meaning both of the entries will get executed .

4. Crontab Example
A line in crontab file like below removes the tmp files from /home/someuser/tmp each day at 6:30 PM.

30     18     *     *     *         rm /home/someuser/tmp/*

Changing the parameter values as below will cause this command to run at different time schedule below :

Note : If you inadvertently enter the crontab command with no argument(s), do not attempt to get out with Control-d. This removes all entries in your crontab file. Instead, exit with Control-c.

5. Crontab Environment
cron invokes the command from the user’s HOME directory with the shell, (/usr/bin/sh).
cron supplies a default environment for every shell, defining:
HOME=user’s-home-directory
LOGNAME=user’s-login-id
PATH=/usr/bin:/usr/sbin:.
SHELL=/usr/bin/sh

Users who desire to have their .profile executed must explicitly do so in the crontab entry or in a script called by the entry.

6. Disable Email
By default cron jobs sends a email to the user account executing the cronjob. If this is not needed put the following command At the end of the cron job line .

>/dev/null 2>&1

7. Generate log file
To collect the cron execution execution log in a file :

30 18 * * * rm /home/someuser/tmp/* > /home/someuser/cronlogs/clean_tmp_dir.log

Booting process in Solaris can be divided in to different phases for ease of study . First phase starts at the time of switching on the machine and is boot prom level , it displays a identification banner mentioning machine host id serial no , architecture type memory and Ethernet address This is followed by the self test of various systems in the machine.

This process ultimately looks for the default boot device and reads the boot program from the boot block which is located on the 1-15 blocks of boot device. The boot block contains the ufs file system reader which is required by the next boot processes.

The ufs file system reader opens the boot device and loads the secondary boot program from /usr/platform/`uname –i`/ufsboot ( uname –i expands to system architecture type)

The boot program above loads a platform specific kernel along with a generic solaris kernel

The kernel initialize itself and load modules which are required to mount the root partition for continuing the booting process.

The booting process undergoes the following phases afterwards :

1) init phase
2) inittab file
3) rc scripts & Run Level

1. INIT phase
Init phase is started by the execution of /sbin/init program and starts other processes after reading the /etc/inittab file as per the directives in the /etc/inittab file .

Two most important functions of init are
a) It runs the processes to bring the system to the default run level state ( Run level 3 in Solaris , defined by initdefault parameter in /etc/inittab )
b) It controls the transition between different run levels by executing appropriate rc scripts to start and the stop the processes for that run level.

2. /etc/inittab file
This file states the default run level and some actions to be performed while the system reaches up to that level. The fields and their explanation are as follows :

S3:3:wait:/sbin/rc3 > /dev/console 2>&1 < /dev/console

S3 denotes a identification if the line

3 is run level
wait is action to be performed

/sbin/rc3 is the command to be run.

So the fields in the inittab are

Identification : run level : action : process

The complete line thus means run the command /sbin/rc3 at run level 3 and wait until the rc3 process is complete.

The action field can have any of the following keywords :

Initdefault : default run level of the system

Respawn : start and restart the process if it stops.
Powerfail : stop on powerfail
Sysinit : start and wait till console in accessible .
Wait : wait till the process ends before going on to the next line.

3. RC scripts & Run Levels
Rc scripts performs the following functions :

a) They check and mount the file systems
b) Start and stop the various processes like network , nfs etc.
c) Perform some of the house keeping jobs.

System goes in to one of the following run level after booting depending on default run level and the commands issued for changing the run level to some other one.

0 Boot prom level ok> or > prompt in Sun.
1 Administrative run level . Single user mode
2 Multiuser mode with no resource sharing .
3 Multiuser level with nfs resource sharing
4 Not used
5 Shutdown & power off (Sun 4m and 4u architecture )
6 Reboot to default run level
S s Single user mode user logins are disabled.

Broadly speaking the running system can be in any of the folloing state

Single user – Minimum processes running , user logins disabled and root password is required to gain access to the shell .
Multiuser - All system processes are running and user logins are permitted

Run level of a desired state is achieved by a number of scripts executed by the rc program the rc scripts are located in /etc/rc0.d , /etc/rc1.d , /etc/rc2.d , /etc/rc3.d & /etc/rcS.d directories . All the files of a particular run level are executed in the alphanumeric order .Those files beginning with letter S starts the processes and those beginning with K stops the processes.

These files are hard linked to the files in /etc/init.d in order to provide a central location for all these files and eliminating the need to change the run level in case these scripts needs to be run separately . The files in /etc/init.d directory are without any S , K and numeric prefix instead a stop / start argument has to be supplied whenever these scripts are to be executed .

By default system has a number of rc scripts needed for run level transition but sometimes it becomes necessary to start some custom scripts at the booting time and turn them off at the shutdown . Custom scripts can be put in any of the required rc directory but following major considerations has to be kept in mind :

* The sequence number of the file should not conflict with other files.
* The sevices needed should be available by previously executed scripts.
* File should be hard linked to the /etc/init.d directory .
* The system looks for only those files beginning with letter K & S , any thing else is ignored , therefore, to make a file inactive simply changing uppercase K or S to lower case will cause system to ignore it .

Accessing the openboot
Openboot console can be accessed by any of the following means . Be careful not to do this on a live system as you might end up in rebooting the server .

1. Rebooting a system , if auto-boot is not set to true rebooted system returns to OK> prompt which is openboot prompt

2. Pressing the keys L1 and A or STOP A , at the same time will bring you to the OpenBoot system. You will see the display
Type b (boot), c (continued), or n (new command mode)
>
Typing b boots the operating system . Typing c resumes the execution of a halted program. Typing n gets you to the Forth monitor, and the prompt will change to ok.

OpenBoot Parameters & commands

Following two tables gives a list of Openboot parameters & commands