UNIXCommands

UNIX COMMANDS

1. $ LOGNAME                  : It displays the current user information

2. $PWD                          : present working directory

3. $DATE                         : It displays the system date & time

4. $clear                           : To clear the screen

5. $cal                               : It current month and year

6. $cal 2000                      : Displays the 2000 year calendar

7. $cal 8 2006                  : displays the 8^th month of 2006

8. $exit or logout             : exit from current user account

9. $ who                          : displays the all user in who are currently working on server

10. $finger                       : displays the all user who are currently working on server with more information

11. Who am I                   : displays current user information?

12. Which or where          : displays the location of the given command

  Syn: $which pwd

13. Cat                            : is use to create new files or to open exiting files or to append data to the exiting files

Create: cat >filename

-----------   

-----------cntl+d(save file)

Redirect: cat file1 file2 file3 >file4--------àredirect output

Append: cat >>filename--------à single file        $cat file1 file2 file3 >>EMP------àmulti files

-----------   

-----------cntl+d

Open file: cat <filename-----àopen single file   $cat file1, file2, file3----------àto open multi files

Cat >.filename---------for hidden files

14. Touch               : It is used to create an empty file i.e. 0 byte file

SYN: $ touch filename

$ touch file1 file2 file3---------à create multiple files

15. rm                    : deleting files or directories

EX

rm filename----------------àdeleting single file

rm -i filename--------------àdeleting files with confirmation

rm file1 file2----------------àdeleting multiple files

rmdir dirname--------------àdeleting the directory but the directory must be empty

rm  -r dirname-------------àdeleting directory recursively (i.e. with tree str)

rm –ri dirname-------------àremove directory with confirmation

rm *   ---------------------à it delete all files

rm  -I *--------------------àdeletes all files with confirmation

rm t* ---------------------àit deletes whose file name starts with ‘t’

16. mkdir               : creating directories

Syn: $mkdir dirname

Sys: $Mkdir .dirname------------àhidden directory

17. Cd          : change directory

Sys: $cd abc

$pwd------/home/testing/abc using above cmd we can come out from abc now we at //home/testing

cd..---------------------------àto come out from current directory

cd../..------------------------àparent directory

cd/---------------------------àit changes to root directory

cd ~-------------------------àit changes to home directory

18. cp                              :copy source file to target file

Ex

Cp emp1 emp2----------------------àemp1 to 2 coping

Cp –I m1 m2-------------------------àoverwrite confirmation? Y

Cp –R source directory to target directory-------cp –R abc xyz

19. mv                               : it is used to rename or move file

Ex: mv exiting filename new filename

           Mv emp .emp----------------------àto hide

          Mv .emp emp--------------------àto unhide

20.ls                       : display, list of all files & directories in a current directory

21.ls|more             : display, list of all files & directories page by page

22. ls –a                 : display, list of all files & directories including hidden files and dirctories also in current directory

23. ls  –r                : display list of all files & directories reverse order in a current directory

24. Ls –R                : display list of all files & directories recursively in a current directory

25. Ls –t                 : display list of all files & directories according to date of creation in a 

current directory

26. Ls –F                : display all list of files & directories, link files, .exe files in a current directory

27. Ls -x                 : display all list of files & directories according to width wise in a current directory

28. Ls -L                 : display all list of files & directories in a current directory in a long list i.e. 9 fields

1) File types

[1) -- For regular file 

ii) d—for dir file 

III) L—for link file 

IV) b—for block of files

V) c— for char files] [here IV, V is device files]

2) File permissions 

3) no. of links

 4) owner name 

5) group name 

6) file size in bytes 

7) Date 

8) time 

9) filename

30. cmp                  : it compares two files char by char

Sys: cmp file1 file2       

Ex: a1: Hello Good Morning

               a2: Hello Good Evening

    If two lines are same then return nothing

     If two files are different then it displays line number with character position

31. comm.              : It display common lines b/w 2 files

           Syn: Comm File1 file2

32. diff                               : it display different lines b/w 2 files

33. pg                    : it display the file contents page by page

                   Syn: $Pg filename

34. more                : it also display the file contents page by page

                   Syn: $more filename

34. head       :it display the 1^st n lines from the file

Sys: $ head –n filename

35. tail                      : it display the last n lines from file

                   Syn: tail –n filename

   Tail +n filename----àit indicates nth line to end of the line 

   Ex: tail +30 file (in this file total no of records is 100) it displays the records from 30^th to 100

36. wc           : it counts the no of lines, words, chars in a given file.

                   Syn: $wc filename

i) wc –l filename------------------àit gives the no of lines in a given file

ii) wc –w filename---------------àit gives the no of words in a given file

III) wc –c filename---------------à it gives no. of char in file

iv) wc -lw filename--------------à it gives the no of lines and character in a given file

Comparing files:

1]$cmp: It compares two files char by char.

Syn:$cmp dile1 file2

Same---doesn’t return any value.

Diff---return char position&line no.

2]$comm: It displays comman lines b/w 2 files.

Syn:$comm file1 file2

3]$diff: It displays diff lines b/w 2 files.

Syn:$diff file1 file2

Zip files:

1]$gzip: To zip the file.

Syn:$gzip filename

Ex:$gzip sample

Sample.gz

2]zcat: it is used for to open zip file in readable format.

$zcat sample.gz

3]$gunzip: To unzip the file.

Syn:$gunzip filename

Ex:$gunzip sample.gz

Sample

FILE ACCESS PERMISSIONS (FAP)

-rwx------

drwxr--r--

-rwx-w--w-

d - Directory

w - Wrire

r - Read

x - Executable

Note: Without write permissions we can’t copy, remove, modify, move, crate

drwxrwxrwx

7 7 7

Directory         – 777

File                  – 666

Default Directory Permissions            – 755

Default File Permissions                     – 644

Read                – 4

Write               – 2

Executable      – 1

Total Permissions 7

TO CHANGE AND MODIFY THE PERMISSIONS

1. Numeric Method

2. Symbolic Method

1. Numeric Method:

Syntax: $ chmod [permissions] <file/Directory>

Ex: $ chmod 700 Dir2

    $ chmod 640 file1

To check the changed permission use the command: ls - l

To change the permissions and check the permission using following command

Ex: $ chmod -c 750 Dir2

To change the permission with Directories and subdirectories with regressively

Ex: $ chmod -R 755 Dir2

To Change the present working Directory Permissions

Ex: $ chmod - R 750

Note : Plz don’t' try this command on the system

2. Symbolic Method

User     – u

Group – g

Others             – o

All       – a

Read    – r

Write   – w

Execute – x

Syntax: $ chmod [options] <File/Directory>

To Add Write permission to Group and Others

Ex: $ chmod g+w, o+w Dir1

To Remove the Write Permission to User

Ex: $ chmod u-w Dir1

To Remove the Write and execute permissions to Group and Others

Ex: $chmod g-r, g-x, o-r, o-x Dir1

Append the Write permissions to all

Ex: $chmod u+w, g+w, o+w Dir1

           (or)

     $chmod a+w Dir1

UMASK (User File Creation Mask)

- cuting, remove, hidden

By Default umask value is 022

Directory         File

777                  666

022                  022

755                  644

GREP Commands:

If you want to save the output in a file in the current directory named new file, enter:

Ex: fgrep dog my file | cut -f5 -d" " | sort > new file

$ grep –n <file> - To display record number

$ grep -i<file>  - To ignore record

$ grep –c <file> - To count in how many records expression

$ grep –E <file> - To search for multiple expression

$ grep –L <file> - It give the file name and which the

                   regular expression

$ grep –r <file> - To search regressively and present working

                   directory

$ grep –w <file> - To search for the exact match for the word

$ grep –s <file> - To suppress errors

$ grep “jai” <file> - It prints the expressive record which

                      have got the “jai”

$ grep –n “jai” <file> - It display the record number and

                         expression what we give “jai”

$ grep –in “jay” <file> - It ignore and prints the record

                          “Jay”

$ grep –E “jay prem” <file> - It search for multiple

                           expressions and prints the record

$ grep –l “jay”*   - It displays the filename which the

                      “Jay” expression is

Process Related Commands:

df:
This command is used to find disk space of the file System.
Syn: df
df -h:
This command is used to find disk space of the human Readable format.
Syn:df -h.

df -k:
This command is used to find disk space of the Kilobites format.
Syn:df -k.

df -kh:
This command is used to find disk space of the Kilobites in human Readable format.
Syn:df -kh.
df -a:
It displays all the data
Syn:df -a.

df -i
This command is used to find disk space in Inodes ,I used, Ifree ,I use .
Syn:df -i.

du:
This command is used to find disk usege of the file System.
Syn: du
du -S
It displays include Sub directories.
Syn: du -S.

du -s:
It display include Total directories.

Syn: du -s

du -a or du -all
It display the space that each file is taking include Sub directories.
Syn: du-a.

du -Sh .
It display include current directory space.
Syn: du -Sh .

du -Sh *
It display all the data in directories.
Syn: du -Sh *

ps:
This is used to current running process.
Syn: ps

ps-aux:
This is used to all the current running process.
Syn:ps-aux.

Top:
It is used find the cpu usage and memory usage.
Syn:Top.

LoadAverage:

The Load Average represenation the Average System load over a period of time.Which Representing the system load during the Last 1,5,15.
Syn:uptime.

nohup:
This command will execute the process even if logout from the System.
Syn:nohup cmd.

vmstat:

netstat:
This command is used to display the all Ipaddrss and portnumber.
Syn:netstat.
Syn:netsat -anp.

find:
This command is used to searching ths files.
Syn:file -/ name Filename.

tar:
tar command is primary archive utilty.
Syn:tar cmd.
tar -cvf:
This is used to create the all files stored in one file (or) Backup file purpose you can use this one.
syn:tar -cvf file.tar f1 f2 f3 f4.

tar -xvf:
This is used to exteance the all files stored in one file.

Syn :tar -xvf file.tar files.

Telnet:
This is used to connect the remote serers.
Syn:telnet ipaddress.

Ftp:
This is used to transfor the files in one system to another system.
Syn:Ftp Ipaddress.

Ping:
This is used to cheek the connectivity.
Syn:ping Ipaddress.

Tracert:
It is used to which can show you the path a packet information takes from your computer to specify .It will list all the routes it passes through until reaches the destination.
Syn:Tracert mediacollege.

Scp:
This is used to secure copy the files in unix system.
Syn:scp filename root@ipaddress filename.

crontab

********

It is a job scheduling tool

crontab -l (it lists all crontab jobs)

crontab -e (edit cront jobs)

-e (edit user's crontab)

-l (list user's crontab)

-r (delete user's crontab)

-i (prompt before deleting user's crontab)

crotab -e

esc+i

-----

------

------

esc: w -save

: q -quit with out save

: wq -save and exit

: wq! - over write