Basic Unix for DB Developers

8/8/2019 Basic Unix for DB Developers

1/40


2/40

Agenda

Introduction - UNIX

General Commands

File System Navigation

File/Directory Manipulation

Data Manipulation

Networking/Communications

Miscellaneous

vi Editor

sed and awk command


3/40

Introduction

Unix Evolution

1969 -- Bell Telephone Laboratories : A joint attempt by BTL, GE, andMIT to create an OS for a large computer which can accommodate upto a thousand simultaneous users.

Ken Thompson and Dennis Ritchie worked on Multicast (MultiplexedInformation and Computing Service)

BTL withdrew from the project and OS was rewritten on anothersmaller machine (a DEC PDP-7 [Programmed Data Processor] with

4K memory for user programs). The result was a system called UNICS (UNiplexed Information and

Computing Service)

UNICS was renamed as UNIX .


4/40

Popular versions of UNIX

SCO UNIX SCO Open Desktop and SCO Open Server from the

Santa Cruz Operation for the Intel platform. Basedon System V.

SunOS Suns early OS and the best-known BSD operatingsystem.

Solaris Suns SRV4 implementation, also referred to as

SunOS 5.x.HP-UX Hewlett-Packards version of UNIX.HP-UX 9.x was

System V, release 3, and HP-UX 10 is based on theSystem V, release 4 OS.

Digital UNIX Digital Equipments version of OSF/1.

IRIX The Silicon Graphics version of UNIX. Early versionswere BSD-based; version 6 is System V, release 4.

AIX IBMs System V-based UNIX.

Linux A free UNIX operating system for the INTELplatform.


5/40

Introduction To Unix OS

The UNIX OS was designed :

By programmers for programmers.

To let a number of programmers access the computer at

the same time and share its resources. To control all of the commands from all of the keyboards

and all of the data being generated.

To permit each user to believe he or she is the only personworking on the computer.

This real-time sharing of resources make UNIX one of themost powerful operating systems ever.


6/40

Features Of UNIX

Multitasking capability

Multi-user capability

Portability

UNIX tools : Integral

Non -Integral

UNIX Communications

Applications libraries


7/40

UNIX Organization

Kernel : schedules tasks and manages storage;Shell : connects and interprets users' commands, calls programs frommemory, and executes them .Tools and applications : offer additional functionality to OS.


8/40

General

exit : Terminate your current session, or shell.

man command : Display the Unix manual page

describing a given Unix command.

login : Type the userid,

press ENTER and supply the password

To logout : exit

To change the password :

$passwd [ENTER]


9/40

General

pwd : writes an absolute path name of thecurrent working directory to standard output.

cd, chdir : change working directory


10/40

The who Utility

The who utility can list :

the user's name

terminal line

login time elapsed time since activity occurred on the line

the process-ID of the command interpreter (shell).

File /var/adm/wtmp, contains a history of all the logins

The general format for output is:

name [state] line time [idle] [pid] [comment] [exit]


11/40

File System Navigation

cd : Return to your home directory. cd directory: Change directory to make directory your current

directory.

file files : Determine file type.

ls : List the contents of the current directory.

ls names : List the contents of the directories; names canname files and/or directories:

ls -l : . . . in a long format, showing permissions, owner,size, and other file info.

ls -a : . . . all files, including "hidden" files (file names that

begin with a dot "."). ls R : . . . Recursively, for all subdirectories.

ls -t : . . . in time order (when modified, newest to oldest)rather than in name order.

pwd : Display the name of the current directory, or "print

working directory."


12/40

File/Directory Manipulation

compress files : Reduces the size of a file.

uncompress files : Restores compressed files to their original form. cp file1 file2: Copy file(s).

cp files directory: Copy file(s) into a directory.

cp -rdir1 dir2 : Copy a directory and, recursively, itssubdirectories.

mkdirdirectory: Create, or "make" a directory.

mv file1 file2: Move a file or, if file1 and file2 are in the samedirectory, rename a file.

mv files directory: Move files into a directory.

mv dir1 dir2: If directory dir2 exists, move dir1 into dir2; otherwise,rename dir1 as dir2.

rm files : Remove (erase) file(s).

rm -rnames : Remove files, directories, and recursively, anysubdirectories.

rmdirdirectory: Remove directory (directory must be empty).


13/40

Data Manipulation

cat files : Concatenate file(s); you can use cat to display the

contents of a file (this is not advisable if the file is a binary file).

grep "pattern" files : Display all lines in the files that match a pattern.

more files : Display contents of files one screen at a time.

sort files : Order the lines in a file or files alphabetically (thiscommand does not alter the file or files -- it merely displays thesorted output to the screen):

sort -rfiles : . . . in reverse order.


14/40


ssh hostname : Connect to a remote host using Secure Shell.

telnet hostname : Connect to a remote host using the telnetprotocol.

talk user : Initiate a conversation with another user (endconversation with Control-C); talk works only between machines of

the same architecture ftp : The command file transfer protocol attaches you to another IP

device

e.g.

ftp 141.205.15.154 ( Attaches you to the device with

address 141.205.15.154. You are normallypresented witha loginandpassword screen )


15/40


Commands that are used in FTP are:

dir- directory listing. quit - quit from ftp. cd - change directory. get ormget - get a file (or multiple files).

put ormput - put a file (or multiple files). bin - sets up your system to receive binary files. hash - displays hashes whilst files are being transferred. lcd - local change directory changes the directory on your local

machine to which you are sending and receiving files. This is usefulas it saves you having to quit ftp to carry out the directory change.

The Hosts file can be found in the directory '/etc'.


16/40


netstat : This stands fornetwork statistics,e.g.

netstat -r displays the routing table of the Unix box.netstat -a displays all network information.

ping : Ping an IP devicee.g.

ping 141.205.51.26

rlogin : This works like telnet,e.g.

rlogin 141.205.52.16 takes you to another Unix machineonly. To quit you press 'return', '~', .' and 'return' again.

Ifconfig : This displays the IP configuration of the box, e.g.e.g.

ifconfig -a displays all IP configuration.


17/40


snoop : This command captures the network packets ina readable formate.g.

snoop -p 23 ( Captures all IP traffic using port 23(Telnet). use Ctrl-C to stop the snoop.)

vstat : This displays CPU utilization and gives a list ofprocesses and their share of CPU utilization,

e.g.vstat 10 ( displays the CPU utilization every 10

seconds.)


18/40

Miscellaneous

!! : Repeat last shell command.

!string : Repeat last shell command that began with string (for example, type"!m" to repeat the last command that began with "m").

cal : Display a calendar of the current month.

cal month year : Display a calendar of the given month and year. Note thatthe year must be fully qualified, for example, "2003" and not "03."

clear : Clears terminal screen.

date : Display the current local date and time.

Difference between who am i, whoami:

who am i : tells me who I am. prompt who am i

On the other hand,

whoami : displays the effective current username.


19/40

df

Displays number of free disk blocks and files .

-a Report on all file systems

-b Print the total number of kilobytes free.

-e Print only the number of files free.

-F FSType Specify the FSType on which to operate.

The -F option is intended for use with unmounted filesystems.

-l Report on local file systems only.

-n Print only the FSType name.

-o FSType-specific_options -t Print full listings with totals.

-V Echo the complete set of file system specific commandlines


20/40

du

Reports on number of 512 bytes blocks ofevery directory in the system.


21/40

recursively descends the directory hierarchy for each

path seeking files that match a Boolean expressionwritten in the primaries given below.

SYNOPSIS

find path... Expression

Example :$find / -name passwd print

$find user singh print

$find name -print

The Find Utility


22/40

cat

The cat utility reads each

file in sequence andwrites it on thestandard output

SYNOPSIS

examplecat file

cat file1 file2 >file3

-n Precede each line output

with its line number.

-b as -n, but omit the linenumbers from blank lines.

-u The output is not buffered.

-s silent about non-existentfiles.

-v Non-printing characters areprinted visibly

cat [-nbsuvet] [file]...


23/40

File access

$ cat > homefiles

echo "files in the home directory \n

cd;pwd

ls -l |more

$ chmod +x homefiles


24/40

chmod

chmod changes or assigns the mode of a file. Themode of a file specifies its permissions and otherattributes.

The mode may be absolute or symbolic.

u user

g group

o other

+ add permission

- remove permission

= Enable setting

r=4 read permission

w=2 write permission

x=1 execute permission


25/40

Examples : chmod

Deny execute permission to everyone: chmod a-x fileAllow only read permission to everyone: chmod 444file

Make a file readable and writable by the group and

others:chmod go+rw file

chmod 066 file

Allow everyone to read, write, and execute the file and

turn on the set group-ID.chmod a=rwx,g+s file

chmod 2777 file


26/40

grep utility

The grep utility searches text files for a pattern and printsall lines that contain that -pattern

grep [-bchilnsvw] limited-regular-expression [filename]


27/40

wc utility

The wc utility reads one or more input files and, by default,

writes the number of newline characters, words and bytescontained in each input file to the standard output.

wc [ -c| -m| -C] [-lw] [file]

-c Count bytes.

-m and -C Count characters.

-l Count lines.

-w Count words delimited by white space

characters or new line characters.Example :

#wc -clw xxx.txt


28/40

More : Browse or page through a text file .

page : page through a text file .

Examples :

more /etc/passwd

more /etc/inittab

More, Page


29/40

head & tail

The head / tail utility copies the first/last number of linesof each filename to the standard output.

The default value of number is 10 lines.

Example :$Head -10 phone.txt

$tail +5 phone.txt


30/40

cmp ,diff ,EOF, BOF

cmp utility compares two files and reports the firstdifference that id fineds.

diff utility echoes the different lines.

Examples :

diff phone.txt phone.old

diff phone.txt phone.old


31/40

Printing files

1. Using cat & cp commands (if printer is connected toterminal port 8):

cat phone.txt > /dev/tty8cp /etc/inittab /dev/tty8

2. If printer is directly connected to the serial printer port onthe CPUcat phone.txt >/dev/ptrs

3. To know the status of the printer : lpstat t

4. Adding files to print-job queue :lp chap1 chap2 chap3


32/40

ps utility

ps (process status) : for viewing the status of allthe unfinished jobs that have been submitted tothe kernel.

Example:

ps -ef

ps -ef | grep yourusername

-e option : include all processes (including others)-f option : give a long listing.


33/40

Killing processes

Use kill utility to terminate processes.

Some processes refuse to die easily, use the "-9"option to force termination of the job.

EXAMPLE: force termination of a job whose process IDis 111

kill -9 111


34/40

The "tar" command stands fortape archive.

This command is used to create new archives, listfiles in existing archives, and extract files fromarchives.

tar


35/40

Vi Editor

The VI editor is a screen-based editor used by many Unix users. The VI editoruses the full screen, so it needs to know what kind of terminal you have. Whenyou log in, wiliki should ask you what terminal you have. The prompt looks likethis: TERM = (vt100)

For C shell (/bin/csh), the command is this:set term=vt100

For Bourne Shell (/bin/sh) or Korn Shell (/bin/ksh), the commands are the

following:export TERM

TERM=vt100

Next, reset your terminal with this command:tset

Starting the vi Editor

The vi editor lets a user create new files or edit existing files. The command tostart the vi editor is vi, followed by the filename.


36/40

Vi Editor

vi or < no filename >( it will ask filenamewhile saving the file.)

Useful vi commands

i : insert mode.

: leave insert mode and go into commandmode.

a : append characters to the end of the line.

o : open a line below your cursor.

O : open a line above. g : go to the bottom of the file.

r : replace the letter that you are on with the one you

type next.


37/40

Vi Editor

x erase the character that you are on. dd delete the line that you are on. A number before dd deletes that

number of lines. yy copy the line you are on. A number before yy copies that number of

lines. p paste the line you are on below you.

P paste the line you are on above you. :wq write and quit the file that you are editing. :wq! write and quit the file that you are editing, even if it is designated as

read only! :w! write to a read only file. :q quit. :q! discard any editing and quit.

/ this takes you to the bottom of the window where you can type a stringand return to perform a search in the file.

Note : (The character! is often referred to as pling )


38/40

sed Command

A stream editor.

Syntax

sed [ -n ] Script[ File ... ]sed [ -n ] [ -e Script] ... [ -fScriptFile ] ... [ File ... ]

Description

The sed command modifies lines from the specified File parameteraccording to an edit script and writes them to standard output. The sedcommand includes many features for selecting lines to be modified andmaking changes only to the selected lines.

The sed command uses two work spaces for holding the line being

modified: the pattern space, where the selected line is held; and the holdspace, where a line can be stored temporarily.


39/40

awk Command

Finds lines in files that match patterns and then performs specified actions on them.

Syntax

awk [ -F Ere ] [ -v Assignment ] ... { -fProgramFile | 'Program' } [ [ File ... | Assignment ... ] ] ...

Description

The awk command utilizes a set of user-supplied instructions to compare a set of files, one line

at a time, to extended regular expressions supplied by the user. Then actions are performedupon any line that matches the extended regular expressions. The maximum record size thatawk processes is 10KB.

The pattern searching of the awk command is more general than that of the grep command, andit allows the user to perform multiple actions on input text lines. The awk commandprogramming language requires no compiling, and allows the user to use variables, numeric

functions, string functions, and logical operators.

The awk command is affected by the LANG, LC_ALL, LC_COLLATE, LC_CTYPE,LC_MESSAGES, LC_NUMERIC, NLSPATH, and PATH environment variables.


40/40

Thank You

Documents

Basic Unix for DB Developers