copy of unix commands.pdf

7/25/2019 Copy of Unix Commands.pdf

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UnixUnix


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Logging In and OutLogging In and Out

As a multi-user system, when connectedto UNIX System through remoteterminal, it will prompt you as:

login:studentpassword: _ Here password is not displayed, and

cursor is on its place as it is. $ is the default prompt, offered by UNIX

System.


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Logging In and OutLogging In and Out

passwdis the simple command in UNIXSystem to change current user password.


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Introductory CommandsIntroductory Commands

date:

?Date is the command used to display systemdate and time.

clear:?Clear is one of the commands to clear the

screen.

?Another command works similarly istput clear


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who

who am I

?Who is the command which will display user

information logged on to the UNIX System,where as who am i is another commandwhich will display information of only aperson who is executing the command.


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man

?Man is a simple utility which will display helpfor any command specified as an argument.

?Another pattern used in some Linux versionsare: --help


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datedate CommandCommand

With datecommand?%m: To display month in digit.

?%h: To display month name

?%d: To display day in digit.?%H: To display hour digits

?%M: To display minute digits

?%S: To display second digits

date +%h %d %H %M


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whowhoCommandCommand

Withwho command:? -H: will display headings for each column

? -u: will display more details including PID.


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ttytty CommandCommand

With ttycommand:? It stands for (TeleTYpe)

?Used to display terminal device on UNIX

System.


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unameuname CommandCommand

With uname command:?uname will simply display domain name of

UNIX System on which you have logged on.

?uname n is the option using which machinename on network.

?uname r will display version of youroperating system


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echoecho CommandCommand

With echo command:? Is used to repeat and display again on screen,

passed as argument.

echo Good Morning

echo Good Morning

echo Good Morning


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tputtput CommandCommand

With tput command:? Is the command for cleaning the screen.

?Another use is to position to relocate cursor.

tput cup 10 20


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bcbc A UNIX CalculatorA UNIX Calculator

With bccommand:? Is used as calculator in UNIX System.

bc

12 + 5 -> 17

12*12 ; 2 32 x=3 ; y=4 ; z=5

p = x + y + z

p -> 12


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HOME DirectoryHOME Directory

When you log in to the system, UNIXautomatically places you in a directorycalled ahome directory.

It is created by the System when the useraccount is created.

?echo $HOME


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Checking path and changing directoryChecking path and changing directory Checking the current directory position:?$ pwd

You can move around in the file system by

using thecdcommand.?$ cd

?$ cd /bin

?$ cd /


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Making DirectoriesMaking Directories

Like DOS, directories can be created withthemkdircommand.

The command is followed by the names

of the directories to be created.?$ mkdir first

?$ mkdir second third fourth


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Removing DictionaryRemoving Dictionary

Thermdir command removesdirectories.

?You cant delete a directory unless it is empty.

?Even directory cant be removed where yourpresent command is.


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File ListingFile Listing

This is simple and powerful command toget list of files and directories.

?$ ls

?$ ls ?$ ls x (Multiple column output)

?$ ls F (Identifying Directories and

Executables with / and * respectively)?$ ls a (Shows Hidden Files presiding .)


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File ListingFile Listing

? -r (Reversing the sort order)? ls xa (Subdirectory

Listing )

? ls xaR? ls l (Long Listing)

? ls t (Sorting files by modification time)

?

ls u (Sorting files by access time)? ls i (Shows inode number for file)


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Creating FilesCreating Files

Cat is useful to create as well as displayfiles in UNIX System.

?$ cat > f1.txt (Creates f1.txt file)

?$ cat f1.txt (Displaying File Contents)?$ cat < f1.txt (Alternate Command)


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Copying FilesCopying Files

The cp command copies a file or a group offiles to destination.

For required two parameters, if two ordinary

files are given, first is copied to second.?$ cp f1.txt f2.txt

If destination file exists, will be overwrittenwithout warning.?$ cp f1.txt first?$ cp f1.txt first/f2.txt


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-i is the option used as interactive copyingoption.

It warns user before overwriting the

destination file.?$ cp i f1.txt f2.txt


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Removing FilesRemoving Files

Files can be deleted with rm.?$ rm

?$ rm * (It wont warn you!!)

?$ rm i * (Interactive Remove Process)?$ rm r * (Removes files and directories

recursively)


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Renaming FilesRenaming Files

mv is very similar to MOVE command inDOS.

It has two purposes, renaming file and

moving group of files and directories todestination directory file.

?$ mv f* second

?$ mv test.script new.script?$ mv second sec


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Printing FilePrinting File

No user is allowed direct access to theprinter.

Instead, one has to spool a job along with

others in a print queue. lp (Line Printing) is the command (or lpr)

to fire print job to the System.

?$ lp test.script


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?$ lp dlaser test.script (specifies thespecific printer name laser)

?$ lptTitleHere test.script (Prints title

on the first page of the print.?$ lp n4 test.script (Specifies the number of

copies 4)

?$ cancel laser (Cancels current job on

printer laser)


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Know your FILE typeKnow your FILE type

There are basically three types of files inUNIX System

?Ordinary

?Directory?Device

file is the command to

identify and display the type of file.


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System is able to differentiate betweentext file, C file, FORTRAN file, shellprogram, executables, directories, empty

files etc.Though this is not accurate utility with all

the flavors.


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Splitting Files into MultiplesSplitting Files into Multiples

When it becomes impossible to workwith large files,split command is used tobreak files into multiple files.?

$ split It splits files default into files namely xaa,

xab, xac and so on. (Max. : 676) Specify additionally file lines as options to

over ride default size of 1000 lines.?$ split 15


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-l is the option which gives a detailed listof the byte number and the differing bytesin octal for character that differs in both

the files.


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Finding CommonsFinding Commons

Commcompares each line of first filewith its corresponding line in second fileand generates output.

Output is divided into three columnsseparated by TABs,?First column contains unique lines in first file.

?Second column contains unique lines in the

second file?Third column contains unique lines in both

the files.


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To drop particular column, -1 | -2 or 3are the options which can be used asparameters.

?$ comm f1 f2 1


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Pattern Matching with Wild CardsPattern Matching with Wild Cards

UNIX System offers several wild cardpatterns to mach the criteria?* : Matches any number of character including

none

?? : Matches a single character

? [abc] : Matches single character either a, bor c

? [!abc] : Matches single character but not a, bor c


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EscapingEscaping

It is generally accepted principle thatfilenames shouldnt contain the shellmeta-characters.

If then do, while accessing, \ is used toescape the sequence (original) meaning ofmeta-characters.

Enter key is also escaped!!

?$ wc l f1 \


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Two or more commands can also becombined and the aggregate output isdiverted to file.

?$ (ls l;who) > newFile


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cal for Calendarcal for Calendar

calcommand is used to display calendar.?$ cal

?$ cal 1993 -1 is the option to display current month

-3 is the command to displayprevious/current/next month

-s displays Sunday as first week day

-m displays Monday as first week day

-j as Julian Date format -y displays calendar of current year


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Tees (And Not Trees)Tees (And Not Trees)

UNIX provides a feature tee - by whichyou can save the standard output in a file,as well as display it on the terminal orpipe it to another process.

teeuses standard input and standardoutput, which means that it can be placedanywhere in a pipeline.

teebreaks up the input into twocomponents, one is saved in a file andanother is passed to standard output.


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?$ ls | tee file.lst?$ cat One | wc l | tee temp.wc

?$ cat Five | wc l | tee a temp.wc

?$ cal | tee a file1 > file2


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