presentation for unix commands

8/8/2019 Presentation for Unix Commands

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UNIX System ProgrammingUNIX System Programming

Under guidance of

Prof. Niranjan Shrivastava

5-12-2010

Compiled by:Preeti VatnaniPushpendra PatelPreeti Soni


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UNIX is an operating system.

An operating system is the program that controls all the other parts of a computer

system, both the hardware and the software.It allocates the computer's resources andschedules tasks. It allows you to make use ofthe facilities provided by the system. Everycomputer requires an operating system.

WhatWhat isis UNIXUNIX ::

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What is LINUX :What is LINUX :

Linux is a free UnixLinux is a free Unix--type operating systemtype operating systemoriginally created byoriginally created by LinusLinus TorvaldsTorvalds withwith

the assistance of developers around thethe assistance of developers around theworld. Developed under the GNU Generalworld. Developed under the GNU GeneralPublic License , the source code for LinuxPublic License , the source code for Linuxis freely available to everyone. Theis freely available to everyone. Thecommands & functions ofcommands & functions of linuxlinux are similarare similartoto unixunix..

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Features of UNIX :Features of UNIX :

UNIX is a multi-user, multi-tasking operatingsystem. Multiple users may have multiple tasksrunning simultaneously. This is very different thanPC operating systems.UNIX is a machine independent operating system.Not specific to just one type of computer hardware.Designed from the beginning to be independent of

the computer hardware.UNIX is a software development environment. Wasborn in and designed to function within this type ofenvironment.

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The shell

The shell acts as an interface between the user and

the kernel. When a user logs in, the login program

checks the username and password, and then startsanother program called the shell. The shell is a

command line interpreter (CLI). It interprets the

commands the user types in and arranges for them to

be carried out. The commands are themselves

programs: when they terminate, the shell gives the

user another prompt (% on our systems).

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Basic UNIX Commands

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Topics

Handling Files and Directories

Text Editors

Compiling and Linking Handling Processes

Archiving and Compressing Files

Other Useful Commands

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Handling Files and Directories

ls : list files

cp : copy files

mv : move files

rm : remove files

mkdir : make directories

cd : change directories

rmdir : remove directories

pwd : print working directory chmod : change permission mode

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ls command

Syntax

ls [-Options] [name ...]

Description

Lists contents of directory.

Frequently Used Options

-a List all entries, including . and ..

-d Do not list contents of directories

-l Long listing

-F Mark directories with a '/', etc.

Examples

ls -alF

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cp command

Syntax

cp [-Options] file1 [file2 ...] target

Description

File1is copied to target. Frequently Used Options

-f Force remove existing file

-i Ask before removing existing file

-r Copy directory trees Examples

cp p1.c p2.c

cp p1.c p2.c mydir

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mv command

Syntax

mv [-Options] file1 [file2 ...] target

Description

File1 is moved to target. Frequently Used Options

-f Removes existing files without prompting the user

-i Asks before removing existing file

Examples mv p*.c mydir

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rm command

Syntax

rm [-f] [-i] file . . .

rm -r [-f] [-i] dirname . . . [file . . .]

Description

Removes files or directories.


-f Removal of files without prompting the user

-i Interactive removal

-r Recursive removal

Examples

rm -f p*.o

rm -r mydir

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mkdir command

Syntax

mkdir [-m mode] [-p] dirname . . .

Description

Creates the specified directories. Options

-m Specifies the mode to be used

-p Create missing intermediate directories

Examples mkdir -m 700 letter

mkdir abc

mkdir - p ./abc/def/ghi

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cd command

Syntax

cd [directory]

Description

Change working directory. If directory is not specified, the value of shell

parameter$HOME is used as the new working

directory.

Examples cd

cd ./abc/def/ghi

cd ..

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rmdir command

Syntax

rmdir [-p] [-s] dirname . . .

Description

Removes directories. Options

-p Remove the directory dirname and its parent

directories which become empty.

-s Suppress the message whenp is in effect Examples

rmdir letter

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pwd command

Syntax

pwd

Description

Prints the path name of the working (current) directory. Examples

pwd

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chmod command

Syntax

chmod [-R] mode file ...

chmod [-R] [ugoa]{+|-|=}[rwxXstl] file ...

Description Changes the permissions mode of a file or directory.

Examples

chmod 444 file1

chmod ugo+rw p*.c chmod 700 mydir

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Handling Processes

ps : Prints information about active processes

kill :Sends a signal to a process

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ps command

Syntax

ps [-Options]

Description

Prints information about active processes. Frequently Used Options

-A Every process now running

-e Same as -A

-f Full listing -l Long listing

Examples

ps -ef

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kill command

Syntax

kill [-signal] pid . . .

kill l (the letter L in lowercase)

Description

Sends a signal to the specified processes.

The value of signal may be numeric or symbolic.

Signal 15is the default signal.

kill l lists the defined signals.

Examples

kill 389

kill 3 401 402

kill -HUP 99999

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Other Useful Commands

grep : search files for a pattern

man : on-line reference manuals

wc : word, line and byte or character count

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grep command - I

Syntax

grep [-E| -F] pattern_list [file . . .]

Description

Searches the input files, selecting lines matching one or

more patterns


-i Case-insensitive search

-l Write file names only

-n Display line number

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grep command - II

Examples

grep -i unix p1.c

grep -n UNIX *.c *.h

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man command

Syntax

man [-Options] [-M path] [-T macropackage] [ -s section] name ...

man [-M path] -k keyword ...

Description

On-line reference manuals Frequently Used Sections

1 User commands and application programs

2 System calls

3 Library functions

Examples

man -s 1 mkdir

man mkdir

man -k pipe

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wc command

Syntax

wc [ file . . . ]

Description

Counts lines, words, and characters

Options

-c Count the number of bytes

-m Count the number of characters

-l Count the number of newline characters

-w Count the number of words Examples

wc -l *.h *.c

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date

Guess what :-)

Displays dates in various formats

% date

% date -u in GMT

% man date


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cal

Calendar

for month

entire year

Years range:1- 9999

No year0

Calendar wascorrected in 1752-

removed 11 days

% cal current month

% cal 2 2000 Feb 2000, leap year

% cal 2 2100 not a leap year

% cal 2 2400 leap year

% cal 9 1752 11 days skipped

% cal 0 error

% cal 2002 whole year

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clear

Clears the screen

Theres an alias for it: Ctrl+L

Example sequence:

% cal % clear

% cal

Ctrl+L


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sleep

Sleeping is doing nothing for some time.

Usually used for delays in shell scripts.

% sleep 2 2 seconds pause


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Command Grouping

Semicolon: ;

Often grouping acts as if it were a single command, so an

output of different commands can be redirected to a file:

% (date; cal; date) > out.txt


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history

Display a history of

recently used commands

% history

all commands in the history

% history 10

last 10

% history -r 10

reverse order

% !!

repeat last command

% !n

repeat command n in the

history

% !-1

repeat last command = !!

% !-2

repeat second last command

% !ca

repeat last command thatbegins with ca


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exit / logout

Exit from your login session.

% exit

% logout


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shutdown

Causes system to shutdown or reboot cleanly.

May require superuser privileges

% shutdown -h now - stop

% shutdown -r now-

reboot


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THANK

YOU5-12-2010

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