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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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Introductory CommandsIntroductory Commands
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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Introductory CommandsIntroductory Commands
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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