linux manual

Linux Manual

M.S.P.V.L.Polytechnic College

LINUX COMMANDS

Aim:

To Write a commands to execute the following.

a) Logon to Unix and Logoff

b) Directory Management commands

c) File Management commands

COMMANDS:

(a) Logon to UNIX and logoff

Log In

To login, enter your username where prompted, hit the Return or Enter key, then

enter your password and hit the Return key again. Here is a sample session.

Syntax:

Username : root

Password : ********

Log Off

You need to know how to end your Unix session by logging off.

To log off, just issue the exit command.

Syntax:

$ exit

Your Unix window should go away. If not, try the command logoff or logout. Or

try pressing the control and D keys on your keyboard simultaneously.

b) Directory management Commands

Creating and Deleting Directories

mkdir

Short for make directory this command is used to create a new directory.

Syntax

mkdir [option] directory

Ex No:Ex No:Ex No:Ex No: 1111 Logon, Logoff Directory & File ManagementLogon, Logoff Directory & File ManagementLogon, Logoff Directory & File ManagementLogon, Logoff Directory & File Management

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Options:

-m mode - Set permission mode (as in chmod), not rwxrwxrwx - umask.

-p - No error if existing, make parent directories as needed.

-v - Print a message for each created directory

-Z - (SELinux) set security context to CONTEXT

directory - The name of the directory that you wish to create.

Output

[root @sample root]# mkdir mydir

[root @sample mydir]# cd

rmdir

Deletes a directory.

Syntax

Options:

-- (ignore-fail-on-non-

empty)

ignore each failure that is solely because a directory is

non-empty.

-p ( --parents) Remove DIRECTORY and its ancestors. E.g., `rmdir -p

a/b/c' is similar to `rmdir a/b/c a/b a'.

-v ( --verbose) output a diagnostic for every directory processed.

--version output version information and exit.

Output

[root @sample root]# ls

1 anaconda-ks.cfg f2 f3 addn copy jey Greet1 john mydir

[root @sample root]# rmdir john


1 anaconda-ks.cfg f1 f2 f3 addn copy jey Greet1

ls

Lists the contents of a directory

rmdir [OPTION]... DIRECTORY...

Linux Manual

M.S.P.V.L.Polytechnic College, Pavoorchatram

Syntax:

Options:

-a - List all files, including the normally hidden . files.

-A - Like -a, but exclude . and .. (the current and parent directories). Solaris

only.

-b - Show nonprinting characters in octal.

-c - List files by inode modification time.

-C - List files in columns (the default format, when displaying to a terminal device).

-d - List only the directory's information, not its contents. (Most useful with -l and -i.)

-f - Interpret each name as a directory (files are ignored).

-F - Flag filenames by appending / to directories, > to doors (Solaris only), *

to executable files, | to fifos, @ to symbolic links, and = to sockets.

-g - Like -l, but omit owner name (show group).

-i - List the inode for each file.

-l - Long format listing (includes permissions, owner, size, modification time, etc.).

-L - List the file or directory referenced by a symbolic link rather than the link itself.

-m - Merge the list into a comma-separated series of names.

-n - Like -l, but use user ID and group ID numbers instead of owner and group names.

-o - Like -l, but omit group name (show owner).

-p - Mark directories by appending / to them.

-q - Show nonprinting characters as ?.

-r - List files in reverse order (by name or by time).

-R - Recursively list subdirectories as well as current directory.

-s - Print sizes of the files in blocks.

-t - List files according to modification time (newest first).

-u - List files according to the file access time.

-x - List files in rows going across the screen.

-1 - Print one entry per line of output.

Output:


1 anaconda-ks.cfg f1 f2 f3 addn copy jey

Greet1

[root @sample root]#

cd

Changes the directory.

ls [options] [names]

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Syntax

Options:

Directory - Name of the directory user wishes to enter.

cd .. - Used to go back one directory on the majority of all Unix shells. It is

important that the space be between the cd and the ..

cd - - When in a Korn shell to get back one directory used to go back one

directory.

Output

[root @sample mydir]# cd john

[root @sample john]#

pwd(Print working directory)

Short for print working directory the pwd command displays the name of the

current working directory.

Syntax

Output

[root @sample root]# pwd

/root

c)File Management Commands

cat

Allows you to look, modify or combine a file.

Syntax

Options:

filename The name of the file or files that you wish to look at or perform tasks on.

-n Precede each line output with its line number.

-b Number the lines, as -n, but omit the line numbers from blank lines.

-u The output is not buffered. (The default is buffered output.)

-s cat is silent non-existent files.

-v Non-printing characters (with the exception of tabs, new-lines and form-

feeds) are printed visibly. ASCII control characters (octal 000 - 037) are

printed as ^n, where n is the corresponding ASCII character in the range

cd [directory]

pwd

cat filename [-n] [-b] [-u]

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octal 100 - 137 (@, A, B, C, . . ., X, Y, Z, [, \, ], ^, and _); the DEL character

(octal 0177) is printed ^?. Other non-printable characters are printed as

M-x, where x is the ASCII character specified by the low order seven bits.

-e A $ character will be printed at the end of each line (prior to the new-

line).

-t Tabs will be printed as ^I's and form feeds to be printed as ^L's.

Output

[root @sample root]# cat f1 f3 > f9



Greet1 f9

chmod

Changes the permission of a file.

Syntax

Options:

-c, --changes - like verbose but report only when a change is made

--no-preserve-root - do not treat `/' specially (the default)

--preserve-root - fail to operate recursively on `/'

-f, --silent, --quiet - suppress most error messages

-v, verbose - output a diagnostic for every file processed

--reference=RFILE - use RFILE's mode instead of MODE values

-R, --recursive - change files and directories recursively

--help - display this help and exit

--version - output version information and exit

Permissions:

u - User who owns the file.

g - Group that owns the file.

o - Other.

a - All.

r - Read the file.

w - Write or edit the file.

x - Execute or run the file as a program.

chmod [OPTION]... MODE[,MODE]... FILE...

chmod [OPTION]... OCTAL-MODE FILE...

chmod [OPTION]... --reference=RFILE FILE...

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Numeric Permissions:

CHMOD can also to attributed by using Numeric Permissions:

400 read by owner

040 read by group

004 read by anybody (other)

200 write by owner

020 write by group

002 write by anybody

100 execute by owner

010 execute by group

001 execute by anybody

Output:

[root @sample root]# chmod 644 f9

[root @sample root]# ls -l

-rw-r—r-- 1 root root 37 May 18 15:38 f9

-rw-r—r-- 1 root root 518 Mar 22 12:22:22 greet1

-rw-r—r-- 1 root root 8 May 18 12:13:16 f2

cp

Copies files from one location to another.

Syntax

Options:

-a, --archive - same as -dpR

--backup[=CONTROL] - make a backup of each existing destination file

-b - like --backup but does not accept an argument

--copy-contents - copy contents of special files when recursive

-d - same as --no-dereference --preserve=link

--no-dereference - never follow symbolic links

-f, --force - if an existing destination file cannot be opened,

remove it and try again

-i, --interactive - prompt before overwrite

-H - follow command-line symbolic links

-l, --link - link files instead of copying

-L, --dereference - always follow symbolic links

cp [OPTION]... SOURCE DEST

cp [OPTION]... SOURCE... DIRECTORY

cp [OPTION]... --target-

directory=DIRECTORY SOURCE...

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-p - same as --preserve=mode,ownership,timestamps

--preserve[=ATTR_LIST] - preserve the specified attributes (default:

mode,ownership,timestamps), if possible additional

attributes: links, all

--no-preserve=ATTR_LIST - don't preserve the specified attributes

--parents - append source path to DIRECTORY

-P - same as '--no-dereference'

-R, -r, --recursive - copy directories recursively

--remove-destination - remove each existing destination file before

attempting to open it (contrast with --force)

--reply={yes,no,query} - specify how to handle the prompt an existing

destination file

--sparse=WHEN - control creation of sparse files

--strip-trailing-slashes - remove any trailing slashes from each SOURCE

argument

-s, --symbolic-link - make symbolic links instead of copying

-S, --suffix=SUFFIX - override the usual backup suffix

--target

directory=DIRECTORY

move all SOURCE arguments into DIRECTORY

-u, --update - copy only when the SOURCE file is newer than the

destination file or when the destination file is

missing

-v, --verbose - explain what is being done

-x, --one-file-system - stay on this file system

Output:

[root @sample root]# cp f3 f10


1 anaconda-ks.cfg f10 f1 f2 f3 addn copy jey Greet1 f9

rm

Deletes a file without confirmation (by default).

Syntax

rm [-f] [-i] [-R] [-r] [filenames |

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Options:

-f - Remove all files (whether write-protected or not) in a directory without

prompting the user. In a write-protected directory, however, files are

never removed (whatever their permissions are), but no messages are

displayed. If the removal of a write-protected directory is attempted, this

option will not suppress an error message.

-I - Interactive. With this option, rm prompts for confirmation before

removing any files. It overrides the -f option and remains in effect even

if the standard input is not a terminal.

-R - Same as -r option.

-r - Recursively remove directories and subdirectories in the argument list.

The directory will be emptied of files and removed. The user is normally

prompted for removal of any write-protected files which the directory

contains. The write-protected files are removed without prompting,

however, if the -f option is used, or if the standard input is not a terminal

and the -i option is not used. Symbolic links that are encountered with

this option will not be traversed. If the removal of a non-empty, write-

protected directory is attempted, the utility will always fail (even if the -f

option is used), resulting in an error message.

Filenames - A path of a filename to be removed.

Output

[root @sample root]# rm f10

Rm: remove regular file ‘f10’? Y


1 anaconda-ks.cfg f1 f2 f3 addn copy jey Greet1 f9

mv

Renames a file or moves it from one directory to another directory.

Syntax

Options:

-f mv will move the file(s) without prompting even if it is writing over

an existing target. Note that this is the default if the standard input is

not a terminal.

-i Prompts before overwriting another file.

oldname The oldname of the file renaming.

mv [-f] [-i] oldname newname

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newname The newname of the file renaming.

filename The name of the file you want to move directory - The directory of

were you want the file to go.

Output

[root @sample root]# mv f3 f11


1 anaconda-ks.cfg f1 f2 f11 addn copy jey Greet1 f9

more

Displays text one screen at a time.

Syntax

Options:

-c Clear before displaying. Redraws the screen instead of scrolling

for faster displays. This option is ignored if the terminal does not

have the ability to clear to the end of a line.

-d Display error messages rather than ringing the terminal bell if an

unrecognized command is used. This is helpful for inexperienced

users.

-e Exit immediately after writing the last line of the last file in the

argument list.

-f Do not fold long lines. This is useful when lines contain

nonprinting characters or escape sequences, such as those

generated when nroff output is piped through ul.

-i Perform pattern matching in searches without regard to case.

-l Ignores form-feed characters (Ctrl + L starts the new page.)

-n number Specify the number of lines per screenful. The number argument

is a positive decimal integer. The -n option overrides any values

obtained from the environment.

-p command For each file examined, initially execute the more command in

the command argument. If the command is a positioning

command, such as a line number or a regular expression search,

set the current position to represent the final results of the

command, without writing any intermediate lines of the file.

-r Displays control keys.

more [-c] [-d] [-e] [-f] [-i] [-l] [-n number] [-p command] [-r] [-s] [-t tagstring]

[-u] [-w] [ -lines ] [ + linenumber ] [ +/ pattern ] [ file ... ]

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-s Doesn't display extra blank lines.

-t tagstring Write the screenful of the file containing the tag named by the

tagstring argument.

-u Ignores backspace and underscores.

-w Normally, more exits when it comes to the end of its input. With -

w, however, more prompts and waits for any key to be struck

before exiting.

-lines Display the indicated number of lines in each screenful, rather

than the default (the number of lines in the terminal screen less

two).

+linenumber Start up at linenumber

+/pattern Displays text two lines before the first time text appears.

filename The name of the file.

Output:

[root @sample root]# more +3 f11

file

Tells you if the object you are looking at is a file or if it is a directory.

Syntax

Options:

-c Check the magic file for format errors. For reasons of efficiency,

this validation is normally not carried out.

-h Do not follow symbolic links.

-m mfile Use mfile as an alternate magic file.

-f ffile ffile contains a list of the files to be examined.

names Specifies the directories of files that you want the information .

Output:

[root @sample root]# vi a.txt

[root @sample root]#file *.txt

a.txt : ASCII text

Result:

Thus the above commands were executed successfully.

file [-c] [-h] [-m mfile] [-f ffile] names

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Aim:

Write a Linux commands to understand the use of general purpose commands.

COMMANDS :

who

Displays who is on the system.

Syntax

Options:

-a Process /var/adm/utmp or the named file with -b, -d, -l, -p, -r, -t, -T, and -u

options turned on.

-b Indicate the time and date of the last reboot.

-d Display all processes that have expired and not been respawned by init .

The exit field appears for dead processes and contains the termination and

exit values (as returned by wait), of the dead process. This can be useful in

determining why a process terminated.

-H Output column headings above the regular output.

-l List only those lines on which the system is waiting for someone to login.

The name field is LOGIN in such cases. Other fields are the same as for user

entries except that the state field does not exist.

-m Output only information the current terminal.

-n x Take a numeric argument, x, which specifies the number of users to display

per line. x must be at least 1. The -n option may only be used with -q.

-p List any other process which is currently active and has been previously

spawned by init . The name field is the name of the program executed by

init as found in /sbin/inittab. The state, line , and idle fields have no

meaning. The comment field shows the id field of the line from

/sbin/inittab that spawned this process.

-q (quick who ) display only the names and the number of users currently

logged on. When this option is used, all other options are ignored.

-r Indicate the current run-level of the init process.

-s (default) List only the name, line, and time fields.

-t Indicate the last change to the system clock (using the date utility) by root.

See su and date.

-T Same as the -s option, except that the state field is also written. state is one

of the characters listed under the /usr/bin/who version of this option. If

who [-a] [-b] [-d] [-H] [-l] [-m] [-nx] [-p] [-q] [-r] [-s] [-t] [-T] [-u] [am i] [ file ]

Ex No:Ex No:Ex No:Ex No: 2 2 2 2 Use Use Use Use of General Purpose Commands in of General Purpose Commands in of General Purpose Commands in of General Purpose Commands in LinuxLinuxLinuxLinux

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the -u option is used with -T, the idle time is added to the end of the

previous format.

-u List only those users who are currently logged in. The name is the user's

login name. The line is the name of the line as found in the directory /dev.

The time is the time that the user logged in. The idle column contains the

number of hours and minutes since activity last occurred on that particular

line. A dot (.) indicates that the terminal has seen activity in the last minute

and is therefore ``current''. If more than twenty-four hours have elapsed or

the line has not been used since boot time, the entry is marked old. This

field is useful when trying to determine whether a person is working at the

terminal or not. The pid is the process-ID of the user's shell. The comment

is the comment field associated with this line as found in /sbin/inittab.

This can contain information where the terminal is located, the telephone

number of the dataset, terminal if hard-wired, and so forth.

am i In the "C" locale, limit the output to describing the invoking user,

equivalent to the -m option. The am and i or I must be separate arguments.

file Specify a path name of a file to substitute for the database of logged-on

users that who uses by default.

Output:

[root @sample root]# who

Root :0 May 18 10:36

[root @sample root]# who –r

Run –level 5 May 18 10:36 last=S

cal

Calendar for the month and the year.

Syntax

Options:

-1 Display single month output. (This is the default.)

-3 Display prev/current/next month output.

-s Display Sunday as the first day of the week. (This is the default.)

-m Display Monday as the first day of the week.

-j Display Julian dates (days one-based, numbered from January 1).

-y Display a calendar for the current year.

month Specifies the month for you want the calendar to be displayed. Must be

the numeric representation of the month. For example: January is 1 and

December is 12.

year Specifies the year that you want to be displayed.

cal [-smjy13] [month] [year]

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A single parameter specifies the year (1 - 9999) to be displayed; note the year

must be fully specified: cal cannot display a calendar for 1989. Two parameters

denote the month (1 - 12) and year. If no parameters are specified, the current

month's calendar is displayed.

Output

[root @sample root]# cal

March 2012

S M Tu W Th F S

1 2 3 4

5 6 7 8 9 10 11

12 13 14 15 16 17 18

19 20 21 22 23 24 25

26 27 28 29 30 31

[root @sample root]# cal 1992

1992

January February March

S M Tu W Th F S S M Tu W Th F S S M Tu W Th F S

1 2 3 4 1 1 2 3 4 5 6 7

5 6 7 8 9 10 11 2 3 4 5 6 7 8 8 9 10 11 12 13 14

12 13 14 15 16 17 18 9 10 11 12 13 14 15 15 16 17 18 19 20 21

19 20 21 22 23 24 25 16 17 18 19 20 21 22 22 23 24 25 26 27 28

26 27 28 29 30 31 23 24 25 26 27 28 29 29 30 31

April May June


1 2 3 4 1 2 1 2 3 4 5 6

5 6 7 8 9 10 11 3 4 5 6 7 8 9 7 8 9 10 11 12 13

12 13 14 15 16 17 18 10 11 12 13 14 15 16 14 15 16 17 18 19 20

19 20 21 22 23 24 25 17 18 19 20 21 22 23 21 22 23 24 25 26 27

26 27 28 29 30 24 25 26 27 28 29 30 28 29 30

31

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July August September


1 2 3 4 1 2 3 4 5

5 6 7 8 9 10 11 2 3 4 5 6 7 8 6 7 8 9 10 11 12

12 13 14 15 16 17 18 9 10 11 12 13 14 15 13 14 15 16 17 18 19

19 20 21 22 23 24 25 16 17 18 19 20 21 22 20 21 22 23 24 25 26

26 27 28 29 30 31 23 24 25 26 27 28 29 27 28 29 30

30 31

October November December


1 2 3 1 2 3 4 5 6 7 1 2 3 4 5

4 5 6 7 8 9 10 8 9 10 11 12 13 14 6 7 8 9 10 11 12

11 12 13 14 15 16 17 15 16 17 18 19 20 21 13 14 15 16 17 18 19

18 19 20 21 22 23 24 22 23 24 25 26 27 28 20 21 22 23 24 25 26

25 26 27 28 29 30 31 29 30 27 28 29 30 31

date

Tells you the date and time in Linux.

Syntax

Options:

%n Insert a newline.

%t Insert a tab.

%m Month of year (01–12).

%d Day of month (01–31).

%y Last two digits of year (00–99).

%D Date in %m/%d/%y format.

%b Abbreviated month name.

%e Day of month (1–31); pad single digits with a space.

%Y Four-digit year (e.g., 1996).

%g Week-based year within century (00–99). Solaris only.

%G Week-based year, including the century (0000–9999). Solaris only.

%h Same as %b.

%B Full month name.

%H Hour in 24-hour format (00–23).

%M Minute (00–59).

%S Second (00–61); 61 permits leap seconds and double leap seconds.

%R Time in %H:%M format.

%T Time in %H:%M:%S format.

date [-a] [-u] [-s datestr]

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%k Hour (24-hour clock, 0–23); single digits are preceded by a space.

Solaris only.

%l Hour (12-hour clock, 1–12); single digits are preceded by a space.

Solaris only.

%I Hour in 12-hour format (01–12).

%p String to indicate a.m. or p.m. (default is AM or PM).

%r Time in %I:%M:%S %p format.

%a Abbreviated weekday.

%A Full weekday.

%w Day of week (Sunday = 0).

%u Weekday as a decimal number (1–7), Sunday = 1. Solaris only.

%U Week number in year (00–53); start week on Sunday.

%W Week number in year (00–53); start week on Monday.

%V The ISO-8601 week number (01–53). In ISO-8601, weeks begin on a

Monday, and week 1 of the year is the one that includes both January

4th and the first Thursday of the year. If the first Monday of January is

the 2nd, 3rd, or 4th, the preceding days are part of the last week of the

previous year. Solaris only.

%j Julian day of year (001–366).

%Z Time-zone name.

%x Country-specific date format.

%X Country-specific time format.

%c Country-specific date and time format (default is %a %b %e %T %Z

%Y; e.g., Mon Feb 1 14:30:59 EST 1993).

Options

-a s.f - (Privileged user only.) Gradually adjust the system clock until it

drifts s seconds away from what it thinks is the “current” time.

(This allows continuous micro-adjustment of the clock while the

system is running.) f is the fraction of seconds by which time drifts.

By default, the clock speeds up; precede s by a -- to slow down.

-u - Display or set the time using Greenwich Mean Time (UTC) .

Strings for Setting the Date

A privileged user can set the date by supplying a numeric string. string consists of

time, day, and year concatenated in one of three ways: time or [day]time or

[day]time[year]. Note: don't type the brackets.

time

A two-digit hour and two-digit minute (HHMM); HH uses 24-hour format.

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day

A two-digit month and two-digit day of month (mmdd); default is current

day and month.

year

The year specified as either the full four digits or just the last two digits;

default is current year

Output:

[root @sample root]# date

Fri May 18 15:51:12 LKT 2012

ln

Creates a link to a file.

Syntax

Options:

-f Link files without questioning the user, even if the mode of target

forbids writing. This is the default if the standard input is not a

terminal.

-n Does not overwrite existing files.

-s Makes it so that it does not create a symbolic link (not on System

V.) existingfile - The file that you want to create a new link.

existingfile Specifies file(s) that you want to create a link to.

newname The new name of the file.

directory The directory were you want the new link.

Output:

[root @sample root]# ln f2 mydir

[root @sample root]#cd mydir

[root @sample mydir]# ls

F1 f2

lp

Prints a file on System V systems.

Syntax:

lp [options] [files]

ln [-f] [-n] [-s] existingfile newname

lp -i request-ID [-c] [-m] [-p] [-s] [-w] [-d destination] [-f form-name] [-H special-

handling] [-n number] [-o options] [-p pagenumbers] [-q priority-level] [-S

character-set | print-wheel] [-t title] [-T content-type [-r]] [-y mode-list]

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Options:

-c Makes a copy of the file that is being printed.

-m Sends e-mail when the printing is done.

-p Enables notification on completion of the print request. Delivery of

the notification is dependent on additional software.

-s Suppresses the display of messages sent from lp.

-w Displays message on screen when printing is done.

-n number The number of files to be printed.

-S

character-

set | print-

wheel

Prints the request using the character-set or print-wheel. If a form

was requested and requires a character set or print wheel other

than the one specified with the -S option, the request is rejected.

Printers using mountable print wheels or font cartridges use the

print wheel or font cartridge mounted at the time of the print

request, unless the -S option is specified.

Printers Using Print Wheels: If print wheel is not one listed by the

LP administrator as acceptable for the printer the request is

rejected unless the print wheel is already mounted on the printer.

Printers Using Selectable or Programmable Character Sets: If the -S

option is not specified, lp uses the standard character set. If

character-set is not defined in the term info database for the

printer, or is not an alias defined by the LP administrator, the

request is rejected.

Output:

tty

Print the file name of the terminal connected to standard input.

Syntax

Options:

-s, --silent, --quiet - Print nothing, only return an exit status.

Output:

[root @sample root]# tty

/dev/pts/0

wc

Short for word count, wc displays a count of lines, words, and characters in a file.

Syntax:

tty [OPTION]...

wc [-c | -m | -C ] [-l] [-w] [ file ... ]

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Options:

-c Count bytes.

-m Count characters.

-C Same as -m.

-l Count lines.

-w Count words delimited by white space characters or new line

characters. Delimiting characters are Extended Unix Code (EUC)

characters from any code set defined by iswspace()

file Name of file to word count.

Output:

[root @sample root]# wc b.txt

2 2 17 b.txt

[root @sample root]# ls -l| wc –l

30

od

od command dumps a file in octal, decimal, and other formats.

Syntax:

Dump the specified files to standard output. The default is to dump in octal

format, but other formats can be specified. With multiple files, concatenate them

in the specified order. If no files are specified or file is -, read from standard input.

With the second form, using the --traditional option, only one file can be

specified.

Options:

For the following options, see the later Arguments section for an

explanation of the arguments bytes, size, and type. If no options are specified, the

default is -A o -t d2 -w 16.

-a - Print as named characters. Same as -ta.

-A - radix, --address-radix=radix

Specify the radix (base) for the file offsets printed at the beginning of each

output line. The possible values are:

d - Decimal.

n - None; do not print an offset.

o - Octal; the default.

x - Hexadecimal.

-b - Print as octal bytes. Same as -toC.

od [options] [files] od --traditional [file] [[+] offset [[+] label] ]

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-c - Print as ASCII characters or backslash escapes. Same as -tc.

-d - Print as unsigned decimal shorts. Same as -tu2.

-f - Print as floating-point. Same as -tfF.

-h - Print as hexadecimal shorts. Same as -tx2.

--help - Display a usage message and exit.

-i - Print as decimal shorts. Same as -td2.

-j bytes, --skip-bytes=bytes

Skip the specified number of input bytes before starting.

-l - Print as decimal longs. Same as -td4.

-N bytes, --read-bytes=bytes

Format and print only the specified number of input bytes.

-o - Print as octal shorts. Same as -to2.

-s bytes, --strings[=bytes]

Output strings that are at least bytes ASCII graphic characters long (default is 3 if

bytes is not specified for --strings).

Arguments

bytes - Specify a number of bytes. Treated as hexadecimal if it begins with 0x or 0X, as

octal if it begins with 0, or as decimal otherwise. Append b to multiply by 512, k

to multiply by 1024, or m to multiply by 10248576.

size - Specified as part of type to indicate how many bytes to use in interpreting each

number. Types a and c do not take a size. For other types, size is a number. For

type f, size can also be one of the following:

D - Double.

F - Float.

L - Long double.

For the remaining types (d, o, u, x), size can be one of the following in addition to

a number:

C - Character.

I - Integer.

L - Long.

S - Short.

type

Specify the format type. The possible types are:

a - Named character.

c - ASCII character or backslash escape.

dsize - Signed decimal, with size bytes per integer.

fsize - Floating point, with size bytes per integer.

o - Octal, with size bytes per integer.

u - Unsigned decimal, with size bytes per integer.

x - Hexadecimal, with size bytes per integer.

Linux Manual


Output:

[root @sample root]# od –d

454

[1]+Stopped od –d

[root @sample root]# od –a

Jhu

[2]+ Stopped od –a

[root @sample root]# od -d b.txt

0000000 25704 26472 27235 2663 26472

26726 30314

Result:


Linux Manual


Aim:

To write a linux commands to implement simple filters.

Commands:

sort

To sort the lines of the named files, use sort.

Syntax

Options

-b - Ignore leading spaces and tabs.

-c - Check whether files are already sorted, and if so, produce no output.

-d - Sort in dictionary order (ignore punctuation).

-f - “Fold”; ignore uppercase/lowercase differences.

-i - Ignore nonprinting characters (those outside ASCII range 040-176).

-k fieldspec - Specify significance of input fields for sorting. See the fuller

description below. Solaris only.

-m - Merge sorted input files.

-M - Compare first three characters as months.

-n - Sort in arithmetic (numerical) order.

-o file Put output in file.

-r - Reverse the order of the sort.

-tc - Fields are separated with c (default is any whitespace).

-T dir Use dir for temporary files. Solaris only.

-u - Identical lines in input file appear only one (u nique) time in output.

-y[kmem] - Adjust the amount of memory (in kilobytes) sort uses. If kmem is

not specified, allocate the maximum memory.

Field Specifications for -k

A fieldspec has the form fieldstart[type][,fieldend[type]].

fieldstart

A field number and optional starting character of the form fnum[.schar].

fnum is the field number, starting from 1. schar, if present, is the starting

character within the field, also counting from 1.

fieldend

A field number and optional ending character of the form fnum[.echar].

fnum is the field number, starting from 1. echar, if present, is the last

significant character within the field, also counting from 1.

sort [options] [files]

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type

A modifier, one of the letters b, d, f, i, M, n, or r. The effect is the same as

the corresponding option, except that the b modifier only applies to the

fields, not the whole line.

Output:

[root @sample root]# sort -b b.txt

Arul

Jeya

Kohila

Krish

[root @sample root]# sort -r b.txt

Krish

Kohila

Jeya

Arul

Paste

Merge corresponding lines of one or more files into vertical columns, separated

by a tab..

Syntax

Options:

Replace a filename with the standard input.

-d'char'

Separate columns with char instead of a tab. char can be any regular

character or the following escape sequences:

Note: you can separate columns with different characters by supplying

more than one char.

\n Newline

\t Tab

\ Backslash

\0 Empty string

-s Merge subsequent lines from one file.

Output:

[root @sample root]# paste a.txt b.txt c.txt > new.txt

[root @sample root]# vi new.txt

paste [options] files

Linux Manual


Pr

Format one or more files according to options to standard output. Each page

includes a heading that consists of the page number, filename, date, and time.

Syntax:

Options:

-a - Multicolumn format; list items in rows going across.

-d - Double-spaced format.

-e[cn] - Set input tabs to every n th position (default is 8), and use c as field

delimiter (default is a tab).

-f - Separate pages using formfeed character (^L) instead of a series of blank lines.

-F - Fold input lines (avoids truncation by -a or -m).

-hstr - Replace default header with string str.

-icn - For output, replace whitespace with field delimiter c (default is a tab)

every nth position (default is 8).

-ln - Set page length to n lines (default is 66).

-m - Merge files, printing one in each column (can't be used with -n and -a).

Text is chopped to fit. See also paste.

-n[cn] - Number lines with numbers n digits in length (default is 5), followed by

field separator c (default is a tab). See also nl.

-on - Offset each line n spaces (default is 0).

-p - Pause before each page.

-r - Suppress messages for files that can't be found.

-sc - Separate columns with c (default is a tab).

-t - Omit the page header and trailing blank lines.

-wn - Set line width to n (default is 72).

+num - Begin printing at page num (default is 1).

-n -Produce output having n columns (default is 1); tabs are expanded as with -i.

Examples

Print a side-by-side list, omitting heading and extra lines:

$pr -m -t list.1 list.2 list.3

Alphabetize a list of states; number the lines in five columns:

$sort states_50 | pr -n -5

pr [options] [files]

Linux Manual


Output:

root @sample root]# pr –a new.txt

2012-05-19 12:18 Page1

Welcome

To

Mspvl

Polytechnic

College

nl

Number the lines of file in logical page segments. Numbering resets to 1 at the

start of each logical page. Pages consist of a header, body, and footer; each section

may be empty.

Syntax

Section Delimiters

\:\:\: Start of header

\:\: Start of body

\: Start of footer

Options

-btype - Number lines according to type. Values are:

a All lines.

n No lines.

t Text lines only (the default).

p"exp" Lines matching the regular expression exp only.

-dxy - Use characters xy to delimit logical pages (default is \:).

-ftype - Like -b, but number footer (default type is n).

-htype - Like -b, but number header (default type is n).

-in - Increment each line number by n (default is 1).

-ln - Count n consecutive blank lines as one line.

-nformat - Set line number format. Values are:

Ln - Left-justify, omit leading zeros.

Rn - Right-justify, omit leading zeros (default).

Rz - Right-justify.

nl [options] [file]

Linux Manual


-p - Do not reset numbering at start of pages.

-sc - Separate text from line number with character(s) c (default is a tab).

-vn - Number each page starting at n (default is 1).

-wn - Use n columns to show line number (default is 6).

Examples

List the current directory, numbering files as 1), 2), etc.:

$ls | nl -w3 -s') '

Number C source code and save it:

$nl prog.c > print_prog

Number only lines that begin with #include:

$nl -bp"^#include" prog.c

Output

[root @sample root]# n1 new.txt

1 Welcome

2 To

3 Mspvl

4 Polytechnic

5 College

Cut

Select a list of columns or fields from one or more files. Either -c or -f must be

specified. list is a sequence of integers

Syntax

cut options [files]

Options

-b list - This list specifies byte positions, not character positions. This is

important when multibyte characters are used. With this option,

lines should be 1023 bytes or less in size. Solaris only.

-clist - Cut the character positions identified in list.

-dc - Use with -f to specify field delimiter as character c (default is tab);

special characters (e.g., a space) must be quoted.

-flist - Cut the fields identified in list.

-n - Do not split characters. When used with -b, cut doesn't split

multibyte characters. Solaris only.

-s - Use with -f to suppress lines without delimiters.

Linux Manual


Examples

Extract usernames and real names from /etc/passwd:

$cut -d: -f1,5 /etc/passwd

Find out who is logged on, but list only login names:

$who | cut -d" " -f1

Cut characters in the fourth column of file, and paste them back as the first

column in the same file. Send the results to standard output:

$cut -c4 file | paste – file

OUTPUT

[root @sample root]# cut –c2 c.txt

C

A

head

Displays the first ten lines of a file, unless otherwise stated.

Syntax

Options:

-number - The number of the you want to display.

-n number - The number of the you want to display.

filename - The file that you want to display the x amount of lines of.

Examples

$head -15 myfile.txt

Display the first fifteen lines of myfile.txt.

Output

[root @sample root]# head -3 new.txt

Welcome

To

Mspvl

tail

Delivers the last part of the file.

Syntax

head [-number | -n number] filename

tail [+ number] [-l] [-b] [-c] [-r] [-f] [-c number | -n number]

Linux Manual


Options:

+number

-number

This option is only recognized if it is specified first. COUNT is a

decimal number optionally followed by a size letter (`b', `k', `m')

as in `-c', or `l' to mean count by lines, or other option letters

(`cfqv').

-l Units of lines.

-b Units of blocks.

-c Units of bytes.

-r Reverse. Copies lines from the specified starting point in the file

in reverse order. The default for r is to print the entire file in

reverse order.

-f Follow. If the input-file is not a pipe, the program will not

terminate after the line of the input-file has been copied, but will

enter an endless loop, wherein it sleeps for a second and then

attempts to read and copy further records from the input-file.

Thus it may be used to monitor the growth of a file that is being

written by some other process.

-c number The number option-argument must be a decimal integer whose

sign affects the location in the file, measured in bytes, to begin the

copying:

+ Copying starts relative to the beginning of the file.

- Copying starts relative to the end of the file.

none Copying starts relative to the end of the file.

The origin for counting is 1; that is, -c+1 represents the first byte

of the file, -c-1 the last.

-n number Equivalent to -c number, except the starting location in the file is

measured in lines instead of bytes. The origin for counting is 1;

that is, -n+1 represents the first line of the file, -n-1 the last.

file Name of the file you wish to display

Linux Manual


Examples

$tail myfile.txt

The above example would list the last 10 (default) lines of the file myfile.txt.

$tail myfile.txt -n 100

The above example would list the last 100 lines in the file myfile.txt.

$tail -f myfile.txt

This next example displays the last 10 lines and then update the file as

new lines are being added. This is a great command to use to watch log files or

logs in real-time.

$tail -f access.log | grep 24.10.160.10

Finally, if you're trying to view a file such as the Apache access log file that

is updated frequently you can pipe its output through the grep command to filter

out only the content you want. In this above example, we're watching the

access.log for any IP address of 24.10.160.10

OUTPUT

[root @sample root]# tail -2 new.txt

Polytechnic

College

Result:


Linux Manual


Aim:

To write a Linux commands to implement advanced filters.

Commands:

egrep

Search one or more files for lines that match a regular expression regexp. egrep

doesn't support the metacharacters $, $, \n, \<, \>, \{, or \}, but does support

the other metacharacters, as well as the extended set +, ?, |, and ( ).

Syntax

Options

-b - Precede each line with its block number. (Not terribly useful.)

-c - Print only a count of matched lines.

-e regexp - Use this if regexp begins with -.

-f file - Take expression from file.

-h - List matched lines but not filenames (inverse of -l).

-i - Ignore uppercase and lowercase distinctions.

-l - List filenames but not matched lines.

-n - Print lines and their line numbers.

-s - Silent mode: print only error messages, and return the exit status.

Not on SVR4, but common on most commercial Unix systems.

-v - Print all lines that don't match regexp.

Examples

Search for occurrences of Victor or Victoria in file:

$egrep 'Victor(ia)?' file

$egrep '(Victor|Victoria)' file

Find and print strings such as old.doc1 or new.doc2 in files, and include their line

numbers:

$egrep -n '(old|new)\.doc?' files

Output

[root @sample root]# egrep ‘spam’ poem.txt

Mary fried a lot of spam

Jill had a lamp spamwich

[root @sample root]# egrep ‘sp(am)?’ poem.txt



egrep [options] [regexp] [files]

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Linux Manual


fgrep

Search one or more files for lines that match a literal, text-string pattern.

Because fgrep does not support regular expressions, it is faster than grep.

Syntax

Options



-e pat - Use this if pat begins with –.

-ffile - Take a list of patterns from file.

-h - Print matched lines but not filenames (inverse of -l).




-s - Silent mode: print only error messages, and return the exit status. Not on

SVR4, but common on most commercial Unix systems.

-v - Print all lines that don't match pattern.

-x - Print lines only if pattern matches the entire line.

Examples

Print lines in file that don't contain any spaces:

$fgrep -v ' ' file

Print lines in file that contain the words in spell_list:

$fgrep -f spell_list file

Output

[root @sample root]# fgrep “spam” poem.txt



grep

Search one or more files for lines that match a regular expression regexp..

Syntax

Options



-e pat - Use this if pat begins with –. Solaris: this option is only available in

/usr/xpg4/bin/grep, not /usr/bin/grep. It is common, though, on many

modern Unix systems.

fgrep [options] [pattern] [files]

grep [options] regexp [files]

Linux Manual


-h - Print matched lines but not filenames (inverse of -l).




-s - Suppress error messages for nonexistent or unreadable files.

-v - Print all lines that don't match regexp.

-w - Restrict regexp to matching a whole word (like using \< and \> in vi). Not

on SVR4, but common on many commercial Unix systems.

Examples

List the number of users who use the C shell:

$grep -c /bin/csh /etc/passwd

List header files that have at least one #include directive:

$grep -l '^#include' /usr/include/*

List files that don't contain pattern:

$grep -c pattern files | grep :0

Output

[root @sample root]# cat> poem.txt

Mary had a little lamp


Jack ate a Spam sandwich


[root @sample root]# grep ‘spam’ poem.txt



[root @sample root]# grep –i ‘spam’ poem.txt


Jack ate a Spam sandwich


[root @sample root]# grep –ic ‘spam’ poem.txt

3

[root @sample root]# grep –i -v ‘spam’ poem.txt

Mary had a little lamp

[root @sample root]# grep –i -v ‘spam’ poem.txt

Result:


Linux Manual


Aim:

To Write a commands to know the details of process status and process management.

COMMANDS:

ps

Reports the process status.

Syntax

Options:

-a List information all processes most frequently requested: all those

except process group leaders and processes not associated with a

terminal.

-A List information for all processes. Identical to -e, below.

-c Print information in a format that reflects scheduler properties as

described in priocntl.

The -c option affects the output of the -f and -l options, as described

below.

-d List information all processes except session leaders.

-e List information every process now running.

-f Generate a full listing.

-j Print session ID and process group ID.

-l Generate a long listing.

-L Print information each light weight process (lwp) in each selected

process.

-P Print the number of the processor to which the process or lwp is

bound, if any, under an additional column header, PSR.

-y Under a long listing (-l), omit the obsolete F and ADDR columns and

include an RSS column to report the resident set size of the process.

Under the -y option, both RSS and SZ will be reported in units of

kilobytes instead of pages.

-g grplist List only process data whose group leader's ID number(s) appears in

grplist. (A group leader is a process whose process ID number is

identical to its process group ID number.)

-n namelist Specify the name of an alternative system namelist file in place of the

default. This option is accepted for compatibility, but is ignored.

ps [-a] [-A] [-c] [-d] [-e] [-f] [-j] [-l] [-L] [-P] [-y] [ -g grplist ] [ -n namelist ] [-o format ]

[ -p proclist ] [ -s sidlist ] [ -t term] [ -u uidlist ] [ -U uidlist ] [ -G gidlist ]

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-o format Print information according to the format specification given in

format. This is fully described in DISPLAY FORMATS. Multiple -o

options can be specified; the format specification will be interpreted

as the space-character-separated concatenation of all the format

option-arguments.

-p proclist List only process data whose process ID numbers are given in

proclist.

-s sidlist List information on all session leaders whose IDs appear in sidlist.

-t term List only process data associated with term. Terminal identifiers are

specified as a device file name, and an identifier. For example, term/a,

or pts/0.

-u uidlist List only process data whose effective user ID number or login name

is given in uidlist. In the listing, the numerical user ID will be printed

unless you give the -f option, which prints the login name.

-U uidlist List information for processes whose real user ID numbers or login

names are given in uidlist. The uidlist must be a single argument in

the form of a blank- or comma-separated list.

-G gidlist List information for processes whose real group ID numbers are given

in gidlist. The gidlist must be a single argument in the form of a blank-

or comma-separated list.

Examples

$ps

Typing ps alone would list the current running processes. Below is an example of

the output that would be generated by the ps command.

PID TTY TIME CMD

6874 pts/9 0:00 ksh

6877 pts/9 0:01 csh

418 pts/9 0:00 csh

$ps -ef

Display full information each of the processes currently running.

UID PID PPID C STIME TTY TIME CMD

hope 29197 18961 0 Sep27 ? 00:00:06 sshd: hope@pts/87

hope 32097 29197 0 Sep27 pts/87 00:00:00 -csh

hope 7209 32097 0 12:17 pts/87 00:00:00 ps –ef

Linux Manual


$ps -l

Displays processes including those that are in a wait state, similar to the below

example.

F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 0 T 0 12308

29722 0 80 0 - 16136 finish pts/0 00:00:00 pico 0 R 0 12530 29722 0 80 0 -

15884 - pts/0 00:00:00 ps 4 S 0 29722 29581 0 80 0 - 16525 wait pts/0

00:00:00 bash

Output

[root @sample root]# ps

PID TTY TIME CMD

2066 PTS/0 00:00:00 cut

2039 PTS/0 00:00:00 grep

2068 PTS/0 00:00:00 ps

[root @sample root]# ps –ef

UID PID PPID C STIME TTY TIME CMD

root 2163 2019 0 10:33 pts/1 00:00:00

bash

root 2193 2019 0 10:40 pts/1 00:00:00

bash

root 2229 1 0 10: ? 00:00:03

/usr/libexec/nau

root 2243 2163 0 11:08 pts/1 00:00:00

ps –ef

…….

…….

[root @sample root]# ps –aux

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

Root 1 0.0 0.2 1336 432 ? S 09:10 0:04 init

Root 2 0.0 0.0 0 0 ? SW 09:10 0:00 [keventd]

……………………

…………………….

Root 2244 0.0 0.4 2766 796 pts/1 R 11:08 0:00 ps –aux

[root @sample root]# ps ux

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

Root 1 0.0 0.2 1336 432 ? S 09:10 0:04 init

Root 2 0.0 0.0 0 0 ? SW 09:10 0:00 [keventd]

……………………

…………………….

Root 2245 0.0 0.4 2624 708 pts/1 R 11:09 0:00 ps ux

Linux Manual


nice

Invokes a command with an altered scheduling priority.

Syntax

Options:

-increment |

-n increment

increment must be in the range 1-19; if not specified, an increment

of 10 is assumed. An increment greater than 19 is equivalent to 19.

The super-user may run commands with priority higher than

normal by using a negative increment such as -10. A negative

increment assigned by an unprivileged user is ignored.

command The name of a command that is to be invoked. If command names

any of the special built-in utilities, the results are undefined.

argument Any string to be supplied as an argument when invoking command.

Examples

$nice +13 pico myfile.txt

Runs the pico command on myfile.txt with an increment of +13.

Output

[root @sample root]# ps –axl

F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY

TIME CMD

100 0 2229 1 15 0 19036 8672 schedu S ?

0:04 /usr/libexe

……………………….

000 0 2292 2019 15 0 4192 1504 wait4 S pts/0

0:00 bash

000 0 2322 2292 16 0 3124 1212 - R pts/0

0:00 ps -axl

[root @sample root]# sudo nice –n 12 bash

[root @sample root]# ps –axl

F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY

TIME CMD

100 0 2229 1 15 0 19036 8672 schedu S ?

0:04 /usr/libexe

……………………….

000 0 2292 2019 15 0 4192 1504 wait4 S pts/0

0:00 bash

000 0 2322 2292 12 0 3124 1212 - R pts/0

0:00 ps –axl

nice [-increment | -n increment ] command [argument ... ]

Linux Manual


kill

Cancels a job.

Syntax

Options:

-s Specify the signal to send, using one of the symbolic names defined in

the <signal.h> description. Values of signal will be recognized in a case

independent fashion, without the SIG prefix. In addition, the symbolic

name 0 will be recognized, representing the signal value zero. The

corresponding signal will be sent instead of SIGTERM.

-l Write all values of signal supported by the implementation, if no

operand is given. If an exit_status operand is given and it is a value of

the ? shell special parameter and wait corresponding to a process that

was ter minated by a signal, the signal corresponding to the signal that

terminated the process will be written. If an exit_status operand is

given and it is the unsigned decimal integer value of a signal number,

the signal corresponding to that signal will be written. Otherwise, the

results are unspecified.

pid One of the following

1. A decimal integer specifying a process or process group to be

signaled. The process or processes selected by positive, negative and

zero values of the pid operand will be as

described for the kill function. If process number 0 is specified, all

processes in the process group are signaled. If the first pid operand is

negative, it should be preceded by -- to keep it from being interpreted

as an option.

2. A job control job ID that identifies a background process group to be

signaled. The job control job ID notation is applicable only for

invocations of kill in the current shell execution environment.

Note the job control job ID pid is available only on systems supporting

the job control option.

Examples

$kill -s kill 100 -165

Kills job 1 of uid 165

When running the kill command you may receive the error "Operation not

permitted", this is often encountered when you're killing the wrong group id

kill [-s] [-l] %pid

Linux Manual


(often 1,2,3 or low number jobs) that you don't have permission to kill. If you

wish to see the group id of the background task run jobs –l\

Output

[root @sample root]# kill -9 2

[root @sample root]# ps ux

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME

COMMAND

Root 1 0.0 0.2 1336 432 ? S 09:10 0:04

init

Root 3 0.0 0.0 0 0 ? SW 09:10 0:00

[kapmd]

……………………

…………………….

Root 2245 0.0 0.4 2624 708 pts/1 R 11:09 0:00 ps

ux

[1] KILLED mail (wd: ~)

nohup

Runs a command even if the session is disconnected or the user logs out.

Syntax

Options:

-a Always changes the signal disposition of target processes. This

option is valid only when specified with -p or -g.

-F Force. Grabs the target processes even if another process has

control. This option is valid only when specified with -p or -g.

-g Operates on a list of process groups. This option is not valid with

-p.

-p Operates on a list of processes. This option is not valid with -g.

pid A decimal process ID to be manipulated by nohup -p.

gpid A decimal process group ID to be manipulated by nohup

--help Displays help screen.

--version Output version information and exit.

nohup command [argument...]

nohup -p [-Fa] pid [pid...]

nohup -g [-Fa] gpid [gpid...]

nohup command [argument...]

Linux Manual


Examples

$nohup find -name '*' -size +1000k > log.txt

In the above example the above find command would be ran using nohup and

continue to perform a find for any file bigger then 1000k regardless of

connectivity logging everything found to the log.txt file.

Output

[root @sample root]# nohup ls &

[1] 2354

[root @sample root]# nohup: appending output to ‘nohup.out’

Exit

[root @sample root]# tail nohup.out

John

Linux

Mspvl

Mydir

Newproject

Nohup.out

[root @sample root]# tail –f nohup.out

John

Linux

Mspvl

Mydir

Newproject

Nohup.out

Result:


Linux Manual


Aim:

To write a communication commands to understand their usage.

COMMANDS

Write

This is a utility for terminal-to-terminal communication. It allows sending

lines from your terminal (console or xterm) to that of another user. The

mesg command may, of course, be used to disable write access to a

terminal

NAME

write - send a message to another user

Syntax

Output

[root @sample root]# who

User1 pts/0 2007-03-10 02:21 (:0.0)

[root @sample root]# write User1 pts/0

Hi Good morning…

Mail

mail - send and receive mail

The mail command allows you to read or send mail. If users is left blank, it allows

you to read mail. If users has a value, then it allows you send mail to those users.

Syntax

Options for reading mail:

-e Check if mail exists. Exit status is 0 if mail exists and 1 if mail does

not exist.

-f file Read mail from mailbox called file.

-F names Forward mail to names.

-h Displays messages in a window.

-i Ignore interrupts

-p Displays all messages.

write user [ttyname]

mail [options] [users]

Ex No:Ex No:Ex No:Ex No: 6 Communication Commands in 6 Communication Commands in 6 Communication Commands in 6 Communication Commands in LinuxLinuxLinuxLinux

Linux Manual


-P Displays all messages with header lines.

-q Terminate when an interrupt occurs.

-r Displays oldest messages first.

-U Convert uucp-type addresses to Internet format.

-v Verbose.

Options for sending mail:

-m type Display a "Message-type:" line at the heading of the message, followed

by type.

-t Display a "To:" line at the heading of the message with the names of the

recipients.

-w Send mail to users without waiting for a remote transfer program to

finish.

-F Save message in a file called the name of the first recipient.

-h n If message has not been sent after n network connections, do not send

message.

-i Ignore interrupts

-r address address is the return address for mail messages.

-s subject Displays subject in the subject header.

-U Convert uucp-type addresses to Internet format.

-v Verbose.

Output:

[root@sample root]$ mail

Subject: MTA

Microsoft Technology Associate exam is conducted for both 2 and 3 year

students.

News:

Description : Displays message to all the users.

Syntax:

$ news [options] [news item]

Option:

-a - displays all of the news items

-s - displays the names of all of the news items.

-c - displays a count of all of the news items

Linux Manual


Output:

[root@sample root]$ cat / user /news/winner

MCA guys are winners in s/w contest at GRD Granddays at 8pm

[su@localhost su]$ news

winner (root) wed dec 10 12:53:50 MCA guys are winners in s/w contest at

GRD Granddays at 8pm.

wall

wall -- To broadcast a message to all users connected to the server. The length of

the message is limited to 20 lines

Syntax

Press Ctrl+d

Output:

[root@sample root]$wall

Do Your Work Perfectly.

[root@sample root]$

Broadcast message from root(pts/0)(Mon Apr 21 15:01:22 2008):

Do Your Work Perfectly.

calendar

Displays appointments and reminders for the date.

Syntax

Examples

$calendar

Display appointments if any.

Result:

Thus the above Communication Commands were executed successfully.

wall [ message ]

Calendar

Linux Manual


Aim:

To write a Linux commands to perform device pattern using meta

character to match each of the following situation.

Commands:

a) ALL TWO CHARACTER FILENAMES.

Syntax:

Output:

[root@sample root]$ ls ??

F1 f2 f6 f9

b) ALL FILENAMES CONSISTING OF TWO LOWERCASE LETTERS.

Syntax:

Output:

[root@sample root]$ ls *[a-z]??


Greet1 f9 doc C3 c5 c6 purple

linux:

mydir:

f1 f2

newproject:

f4

C)ALL FILENAMES ENDING WITH C.

Syntax:

Output:

[root@sample root]$ ls *c

doc

$ ls ??

$ls *[a-z]??

$ ls *c

Ex No:Ex No:Ex No:Ex No: 7 Device Patter7 Device Patter7 Device Patter7 Device Patternnnn using Meta Character in using Meta Character in using Meta Character in using Meta Character in LinuxLinuxLinuxLinux

Linux Manual


D)ALL FILENAMES BEGINNING WITH C AND ENDING WITH DIGIT

Syntax:

Output:

[root@sample root]$ ls c*[0-9]

C3 c5 c6

E)ALL FILENAMES BEGINNING WITH P AND HAVING AT SOMEWHERE

Syntax:

Output:

[root@sample root]$ ls p*?p*

purple

Result:


$ ls c*[0-9]

$ls p*?p*

Linux Manual


SHELL SCRIPTS PROGRAMS

Aim:

To write a Shell script program that accepts a numerical value N & display

the decremented value of N till it reaches 0.

Procedure:

1. Create a new vi editor file.

2. Get the integer value of n.

3. Check the n value greater than zero then print the n value.

4. Decrement the variable n.

5. Repeat the steps up to this condition false.(i.e. n>0)

6. Print the result.

Program

#!bin/bash

echo “ENTER THE INTEGER VALUE: ”

read n

while [ $n –ge 0 ]

do

echo “$n”

let n—

done

Output

[root@sample raja]# bash addn

ENTER THE INTEGER VALUE:

6

6

5

4

3

2

1

0

Result:

Thus the Shell script program to display the decremented integer value

was executed successfully.

Ex No:Ex No:Ex No:Ex No: 8 8 8 8 Display the decremented value of N.Display the decremented value of N.Display the decremented value of N.Display the decremented value of N.

Linux Manual


Aim:

To Write a Shell script program that takes three command line arguments.

The first argument is the name of the destination file and the other two

arguments are names of files to be placed in the destination file.

Procedure:


2. Get the name of the destination file, 1st source file and 2nd source file.

3. Concatenate the two files and copied into the destination file.

4. Check the file status with 0.

5. If it is equal then print “File Copied Successfully” otherwise print

“Problem copying file”.

Program

#!/bin/bash

echo “Enter the name of the destination file : “

read dest

echo “Enter the name of the 1st source file : “

read src1

echo “Enter the name of the 2nd source file : “

read src2

cat $src1 $src2 > $dest

status=$?

If [ $status –eq 0 ]

Then

echo “File Copied Successfully”

Else

echo “Problem copying file”

fi

Output

[root@sample jeya]# bash copy

Enter the name of the destination file : F1

Enter the name of the 1st source file: F2

Enter the name of the 2nd source file: F3

File copied successfully.

Result:

Thus the program to move the two files into another file using command

line arguments was executed successfully.

Ex No:Ex No:Ex No:Ex No: 9999 Performing File MomentPerforming File MomentPerforming File MomentPerforming File Moment Using Using Using Using

Command Line ArgumentsCommand Line ArgumentsCommand Line ArgumentsCommand Line Arguments

Linux Manual


Aim:

To write a Shell script program to print the content of the file from the

given line number to the next given line number.

Procedure:


2. $# -eq 0, then print the Error msg.

3. If $# -eq 3,

a. If $# -eq 3, then print the content from the given line number.

b. Else print the Error opening file

4. Else print the missing arguments.

Program

#!/bin/bash

if [ $# -eq 0 ]

then

echo "$0:Error command arguments missing!"

echo "Usage: $0 start_line uptoline filename"

echo "Where start_line is line number from which you would like to

print file"

echo "uptoline is line number upto which would like to print"

echo "For eg. $0 5 5 myfile"

echo "Here from myfile total 5 lines printed starting from line no. 5 to"

echo "line no 10."

exit 1

fi

if [ $# -eq 3 ]; then

if [ -e $3 ]; then

tail +$1 $3 | head -n$2

else

echo "$0: Error opening file $3"

exit 2

fi

else

echo "Missing arguments!"

fi

Ex No:Ex No:Ex No:Ex No: 10 10 10 10 Printing the file ContentPrinting the file ContentPrinting the file ContentPrinting the file Content

Linux Manual


Output

[root@sample jeya]# bash print file 5 5 copy

read src1

echo “Enter the name of the 2nd source file : “

read src2

cat $src1 $src2 > $dest

status=$?

Result:

Thus the Shell script program to print the content of the file from

the given line number to the next given line number was executed

successfully.

Linux Manual


Aim:

To write a Shell script program to say Good morning/Afternoon/Evening

as u log into system.

Procedure:


2. Set the value of hour.

3. Compare the hour with time of zero, 12and 18.

4. If it is greater than 0 and less than 12 print the string is GOOD MORNING

then

if it is greater than 12 and less than 18 print the string is GOOD

AFTERNOON otherwise print the string is GOOD EVENING.

Program

#!/bin/bash

Hour=$(date + “%H”)

If [ $hour –ge 0 –a $hour –lt 12 ]

Then

Greet=”GOOD MORNING,$USER”

elif [ $hour –ge 12 –a $hour –lt 18 ]

Then

Greet=”GOOD AFTERNOON,$USER”

Else

Greet=”GOOD EVENING,$USER”

Fi

Echo $greet

Output

[root@sample raja]# bash greeting

GOOD AFTERNOON, root

Result:

Thus the Shell script program to say Good morning/Afternoon/Evening as u

log into system was executed successfully.

Ex No:Ex No:Ex No:Ex No: 11a 11a 11a 11a Display the Message in Login SessionDisplay the Message in Login SessionDisplay the Message in Login SessionDisplay the Message in Login Session

Linux Manual


Aim:

To write a Shell script program to print the date information.

Procedure:


2. Enter the command is date.

3. Print the today date information.

Program

#!/bin/bash

TODAY=$(date + “%X %a %d %b %Y”)

Echo “------------------------------------------------“

Echo “Today Date : $TODAY”

ECHO “-----------------------------------------------“

Output

[root@sample jeya]# bash date

-----------------------------------------------------------

Today Date : 03: 52 :33 PM Thu 17 May 2012

-----------------------------------------------------------

Result:

Thus the Shell script program to print the date information was executed

successfully.

Ex No:Ex No:Ex No:Ex No: 11b 11b 11b 11b To To To To Print the date Print the date Print the date Print the date in a Dein a Dein a Dein a Deccccided ided ided ided FormatFormatFormatFormat

Linux Manual


Aim:

To Write a Shell script program that tells u its name and PID.

Procedure:


2. Enter the command is Ps –u into file.

3. Print the name and PID information.

Program

#!/bin/bash

Ps –u

Output

[root@sample jeya]# bash p1

USER PID %CPU %MEM VSZ RSS TTY STAT START

TIME COMMAND

Root 850 0.0 0.9 4300 1664 pts/0 s 11.13 0:02

bash

Result:

Thus the Shell script program was executed successfully.

Ex No:Ex No:Ex No:Ex No: 12 12 12 12 Shell script that tells Shell script that tells Shell script that tells Shell script that tells yoyoyoyou its name and PIDu its name and PIDu its name and PIDu its name and PID

Linux Manual


Aim:

To develop a Basic Math calculator Using case Statement.

Procedure:

1) Create a new file.

2) Read the operands.

3) Select any one operation from the list.

4) Perform the operation.

5) Print the result.

Program:

# Implementation of Calculator application

#!bin/bash

j=1

while [ $j -eq 1 ]

do

echo "Enter the First Operand;"

read f1

echo "Enter the second operand:"

read f2

echo "1-> Addition"

echo "2-> Subtraction"

echo "3-> Multiplication"

echo "4-> Division"

echo "Enter your choice"

read n

case "$n" in

1)

echo "Addition"

f3=$((f1+f2))

echo "The result is:$f3"

;;

2)

echo "Subtraction"

let "f4=$f1 - $f2"


;;

3)

Ex No:Ex No:Ex No:Ex No: 13 Basic 13 Basic 13 Basic 13 Basic Calculator Using Calculator Using Calculator Using Calculator Using Switch Switch Switch Switch CaseCaseCaseCase

Linux Manual


echo "Multiplication"

let "f5=$f1 * $f2"


;;

4)

echo "Division"

let "f6=$f1 / $f2"


;;

esac

echo "Do you want to continue(press:1 otherwise press any key to

quit)"

read j

done

Output:

[su@localhost su]$ bash u

Enter the First Operand;

23

Enter the second operand:

23

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

1

Addition

The result is:46

Do you want to continue(press:1 otherwise press any key to quit)

1


20


2

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

2

Linux Manual


Subtraction

The result is:18


1


24


2

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

3

Multiplication

The result is:48


1


24


12

1-> Addition

2-> Subtraction

3-> Multiplication

4-> Division

Enter your choice

4

Division

The result is:2


q

[su@localhost su]$

Result:

Thus the above program to develop a calculator application was executed

successfully.

Linux Manual


Aim:

To Write a Shell script program that that takes a login name as a command

line argument & reports when that person logs in. Send greeting to that person.

Procedure:


2. Enter the command in to file.

3. Print the logged on to the system information.

Program

#!/bin/bash

Echo “The user $argv[1] is logged on to the system on”

Who | grep “$argv[1]” | cut –c22-38

Output

[root@sample jeya]# bash e2

The user [1] is logged on to the system on

May 17 11:12

Result:

Thus the Shell script program to that that takes a login name as command

line argument & reports when that person logs in. Send greeting to that person

was executed successfully.

Ex No:Ex No:Ex No:Ex No: 14 Sent the Greeting to user14 Sent the Greeting to user14 Sent the Greeting to user14 Sent the Greeting to user

Linux Manual


Aim:

To write a Shell script program that takes a command line argument and

reports on whether it’s a file or directory or something.

Procedure:


2. Get the name of the file or directory.

3. Compare the name of the file or directory.

4. If it is file name print the string is file then if it is directory name print the

string is Directory otherwise print the string is Not.

Program

#!/bin/bash

echo "Enter a file name:"

read f

if [ -f $f ]

then

echo "File"

elif [ -d $f ]

then

echo "Directory"

else

echo "Not"

fi

Output

[root@sample jeya]# bash report

Enter a file name:

F1

File

Result:

Thus the Shell script program to takes a command line argument & reports

on whether it’s a file or directory or something was executed successfully.

Ex No:Ex No:Ex No:Ex No: 15 Report15 Report15 Report15 Report

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