OPERATING SYSTEM LAB. MANUAL

Lab.1 : Linux Commands:

A. Basic linux commands

$ ls (list short)

this command is used for finding out what is in the current directory. It list the contents of the current working directory.

$ ls –a : used for listing all files including hidden

$ ls –l : used for listing all files in details excluding hidden files

$ ls list* : used for listing the files that names start with “list” in the current workng director

$ ls *list : used for listing the files that names ends with “list” in the current working directory

$ ls ~/betul : used for listing the contents of your betul directorywhich isunder your home directory

$ mkdir (make directory)

this command is used for creating a new directory into the present working directory.

$ mkdir betul : used for creating a directory called betul into the current working directory.

$ cd (change directory)

this command is used for changing the cureent working directory to a different directory.

$ cd betul : changes the current working directory to the directory called betul

$ cd : used for returning the home directory

$ cd .. :used for taking one directory up in the hierarchy

Note: In unix and linux there are two special directories called ‘.’(dot) and ‘..’(two dot or double dot). ‘.’ means the current directory and ‘..’ means the parent of the current directory

$ pwd (print working directory)

this command is used for finding out the absolute pathname of your present working directory.

$ cp (copy)

this command used for copying files.

$ cp filename copy-filename : is used for copying a file with another name at the same directory

$ cp filename directoryname : is used for copying a file from the current directory to another subdirectory. In this case the file is copied with the same name

$ cp filename directoryname/new-filename : is used for copying a file from the current directory to another subdirectory. In this case the file is copied with diffrent name.

$ cp ../filename : is used for copying the file from the directory above (represented by “..”) to the current directory

$ mv (move)

this command is used for renaming or moving files.

$ mv old-filename new-filename : renames original file with new-filename

$ mv filename directory-name/filename : moves file to another directory with keeping the same filename

$ mv filename directory-name/new-filename : moves file to another directory with giving another filename

$ rm (remove)

this command is used for deleting files.

$ rm filename : removes file from the current directory

$ rm director-name : removes the file from another directory

$ rm ../filename : removes file from directory above

$ rmdir (remove directory)

this command is used for removing directory. Note that unix will not allow removing non-empty directories.

$ rm –r directory-name : is used for removing a directory with files. ( -r means recursive)

$ clear (clear screen)

this command clears all text and leave $ prompt at the top of the window.

$ find

this command is used for finding files. It is used with –name flag. The directory must be specified.

$ find . –name myfile : searches the file called myfile in the current directory

$ find directory/ -name myfile : seaches the file called my file in the given directory

B. File Operations

B1. Displaying the contents of a file on the screen

$ less

this command is used for displaying the contents of a file on the screen. It wites the contents of a file onto the screen a page at a time.

$ less filename

$ head

this command is used for displaying the contents of a file on the screen. By deafult it displays first ten lines of a file.

$ head –6 myfile : displays the first 6 lines of the file

$ tail

this command is used for displaying the contents of a file on the screen. By deafult it displays last ten lines of a file.

$ tail –6 myfile : displays the last 6 lines of the file

$ wc (word cout)

this command is used for finding out how many lines the file has.

$ wc –l science.txt

$ cat (concatenate)

this command is used for displaying the contents of a file on the screen. If the file is longer than the size of the window, it scrolls past making it unreadable

$ cat filename

If the cat command is written without specifying a file to read, it reads the standard input and on receiving the “end of file” (^D), copies it to the standard output.

Ex1. Ex.2

$ cat $ cat

bir bir

iki bir

uc iki

^D iki

bir uc

iki uc

uc ^D

$ $

The ‘>’ symbol is used for redirecting the output of a command.

$ cat > list1

apple

Creates a list1 file that contains a list of fruit

banana

pear

^D

The ‘>>’ symbol is used for appending standard output to a file.

Adds more items to the file list1

$ cat >>list1

grape

pineapple

^D

$ cat list1 list2 >biglist : writes the contends of the list1 and list2 into the file called biglist respectively.

B2. Searching the contents of a file

$ grep

this command is used for searching files for specified words or patterns. It is case sensitive.

$ grep science science.txt : search science word in the science.txt file and print out each line containing the word science.

$ grep –i ‘spinning top’ science.txt : search ’spinning top’ pattern in the science.txt file with ignoring upper*lower case distinctionss

options of grep command:

-v : displays those lines that do not match

-n : precede each matching line with the lin number

-c: prints only the total count of matched lines

$ grep –ivc science science.txt : displays the number of lines without the words science or Science

$ sort

this command is used for sorting alphabetically or numerically sorts a list.

$ sort

carrot

beetroot

artichoke

^D

artichoke

beetroot

carrot

$ sort < biglist ($ sort biglist ) : outputs the sorted list to the screen

$ sort < biglist > sortedlist : writes the output of the sorted list into the file called sortedlist