LINUX COMMANDS PART 2

  • date 15th January, 2022 |
  • by Prwatech |
  • 0 Comments

LINUX                                MODULE 5 and 6 

CAT COMMAND 

Use of this command: 

  • cat displays the contents in the file 
  • cat used to create a file (not folder) also used to append the content of a file  

1) To create the new file in current directory :

 

cat   >  prwa.txt

Then, add your contents in it,  

Example:  

This is the training institution     

which is located in banglore and pune. 

To return to the same directory  

Ctrl+d 

 

To check whether the content is created or not  

ls

a.txt     btm         c.txt  layout  megha.txt  poi       prwa.txt 

or to see in detail 

 

ls  –ltr

To display the same content 

 

cat  prwa.txt

 

This is the training institution 

which is located in banglore and pune. 

 

or   

 

nl  prwa.txt

 

 

 

     1 This is the training institution.  

     2 which is located in banglore and pune. 

 

3) In case If you want append the above content then, 

 

cat  >>  prwa.txt

 

hen add your content  

we mainly focused on Datascience , BigData , Google colud. 

ctrl+d 

 

 To see the all content

 

cat  prwa.txt

 

To check the number (n) of lines in the content:

 

cat  -n  prwa.txt

 

     1 This is the training institution.  

     2 which is located in banglore and pune. 

     3 we mainly focused on Datascience , BigData and Google cloud. 

     4  

     5  

     6 thank you 

 

5) To neglect the blank (b) spaces  and numbering the remaining lines 

 

cat  -b  prwa.txt

 

   

     1 This is the training institution.  

     2 which is located in banglore and pune. 

     3 we mainly focused on Datascience , BigData and Google cloud. 

                                                                                                

                                                                                    

     4 thank you 

 

 

6) To drop all the contents of a file 

 

cat  prwa.txt > prwa.txt

 

File will be empty 

 

7) To create empty file

 

Data.txt

 

Where Data.txt is file name. 

To check the size of the file, it will be zero

8) To end (e) the content line with $ symbol

 

cat  -e  prwa.txt

 

 

This is the training institution.$  

which is located in banglore and pune.$ 

we mainly focused on Datascience , BigData and Google cloud.$ 

$ 

$ 

thank you$ 

 

9) To copy one file content to another file 

 

prwa.txt > new.txt

where, new.txt is newly created file 

user@ubuntu:~/Desktop$ cat  prwa.txt 

This is the training institution. 

which is located in banglore and pune. 

we mainly focused on Datascience , BigData and Google cloud. 

 

thank you 

user@ubuntu:~/Desktop$ cat  new.txt 

This is the training institution. 

which is located in banglore and pune. 

we mainly focused on Datascience , BigData and Google cloud. 

 

thank you 

10). To append the one file content with another file content 

 

cat > start.txt

 

welcome to prwatech 

ctrl+d 

now I want attach start.txt file content with prwa.txt file 

cat prwa.txt >> start.txt 

 

cat start.txt 

 

welcome to prwatech 

This is the training institution. 

which is located in banglore and pune. 

we mainly focused on Datascience , BigData and Google cloud. 

 

 

thank you  

  To add one or more file to new file 

 

cat  >  p.txt 

1 

2 

3 

Clt+d 

cat  >  q.txt 

4 

5 

6 

Clt+d 

cat  >  r.txt 

7 

8 

9 

Clt+d

 

Check the size of the file after creation and after appending with 2 or more files 

It will be p.txt + q.txt + r.txt =w.txt 

Then

 

cat p.txt q.txt r.txt  > w.txt  
cat w.txt 

1 

2 

3 

4 

5 

6 

7 

8 

9

 

MKDIR COMMAND: 

  • mkdir is a command to create directory   

 

  1. To create the directory 

 

Mkdir  prwatech

To check the created directory 

 

ls

 

To create simultaneously directory  

 

mkdir delhi  hyderbad  kerala

 

  1. To create the folder in directory without going inide it 

 

mkdir  prwatech/office

 

 

 

let’s see office directory in prwatech directory 

 

cd  prwatech

 

  1. same way lets create two  or more folders in side office in single command 

 

             

  mkdir  office/first  floor   office/ second  floor

 

 

 

                  mkdir: cannot create directory ‘office/’: File exists 

                   mkdir: cannot create directory ‘floor’: File exists 

                 this because there should not be any space between directory name(first..floor) 

 

               mkdir  office/firstfloor  office/secondfloor 

check the current root 

 

pwd

 

 

/home/user/Desktop/prwatech 

Currently we are in prwatech directory 

let’s  check directories in prwatech 

 

ls

 

 

office 

let’s  go inside the office directory 

cd  office 

and check directories in office 

ls 

firstfloor  secondfloor 

 

  1. if we don’t need any msg after creating the directory then, 

 

before this check the path 

pwd 

/home/user/Desktop/prwatech/office 

let’s  come back to prwatech directory 

So,  cd .. 

Now check path 

pwd 

Ok we are in prwatech 

/home/user/Desktop/prwatech 

 

Now we will create good as directory in prwatech 

 

mkdir  -p  good   or mkdir  -pv  good

 

 

Here there will no message after creating good directory 

To check current directories in prwatech 

ls 

good  office 

 

Now we will create one more bad as directory  

 

mkdir  -v  bad     or   mkdir  -vp  bad

 

 

mkdir: created directory ‘bad’  

This message will pop up 

Now check the directories 

ls 

bad  good  office 

 

  1. now you want to give permission before modifying 

 

mkdir  -m421  week

 

 

To check the directories 

ls 

bad  good  office  week 

let’s  see in detail 

ls  -ltr 

total 16 

drwxr-xr-x 4 user user 4096 Dec 30 06:48 office 

drwxr-xr-x 2 user user 4096 Dec 30 07:12 good 

drwxr-xr-x 2 user user 4096 Dec 30 07:23 bad 

dr—w—x 2 user user 4096 Dec 30 07:30 week 

Here you can see the permission column with different code 

 

Now try to go inside the directory week 

cd week 

bash: cd: week: Permission denied 

user@ubuntu:~/Desktop/prwatech$ ls 

 

office 

 

REMOVE(RM) COMMAND 

  • It is used for remove file or directory. 

 

  1. To remove the file from the current directory 

 

Command: 

 

rm

 

Before: 

a.txt       c.txt     d.txt  hyderbad  lin        poi       p.txt     r.txt 

banglore    Data.txt  dumy   kerala    megha.txt  prwatech  q.txt     start.txt 

corona.txt  delhi     numbers.txt    layout    new.txt    prwa.txt  rajkumar 

 

Operation :

 

rm start.txt

 

 

Output:  

a.txt       c.txt     d.txt  hyderbad  lin        poi       p.txt     r.txt 

banglore    Data.txt  dumy   kerala    megha.txt  prwatech  q.txt 

corona.txt  delhi     numbers.txt   layout    new.txt    prwa.txt  rajkumar 

 

there is no start.txt file in the Desktop directory 

 

  1. To ask YES or NO permission(i) before removing the file. 

 

Command:  

 

rm  -i

 

 

Operation:

 

rm  -i  numbers.txt

 

 

 message will be pop up 

rm: remove regular file ‘numbers.txt’? 

 just type yes 

 

To deny the remove permission 

 

Operation:

 

rm   -i   megha.txt

 

 

Message will be pop up 

rm: remove regular file ‘megha.txt’? 

Say no 

 

Output:  

a.txt       c.txt     d.txt     kerala  megha.txt  prwatech  q.txt 

banglore    Data.txt  dumy      layout  new.txt    prwa.txt  rajkumar 

corona.txt  delhi     hyderbad  lin     poi        p.txt     r.txt 

 

  • NOTE: IF YOU WANT  TO SEE WEATHER IT IS FILE OR DIRECTORY, WHITE COLOR OBJECTS ARE FILE AND BLUE COLOR OBJECTS ARE DIRCTORY 

 

  1. To remove file completely  

Command:  

 

rm  -rf

 

 

Operation: 

 

rm  -rf megha.txt   or rm  -f  megha.txt

 

 

Before: 

a.txt       c.txt     d.txt     kerala  megha.txt  prwatech  q.txt 

banglore    Data.txt  dumy      layout  new.txt    prwa.txt  rajkumar 

corona.txt  delhi     hyderbad  lin     poi        p.txt     r.txt 

 

Output:  

a.txt     corona.txt  Data.txt  d.txt  hyderbad  layout  new.txt  prwatech  p.txt  rajkumar 

banglore  c.txt       delhi     dumy   kerala    lin     poi      prwa.txt  q.txt  r.txt  

 

NOTE:  

  1. we can’t open directory using cat command, to open  command we have to use cd <name> 

Operation: 

 

cat rajkumar

 

 

output:  

cat: rajkumar: Is a directory 

  1. we can remove directory use rm command  

 

Operation:  

 

rm rajkumar

 

 

output:  

rm: cannot remove ‘rajkumar’: Is a directory 

 

 

  1. To remove directory completely 

Command:

 

  rm  -r

 

 

Operation: 

 

rm  -r  rajkumar

 

 

Before: 

a.txt     corona.txt  Data.txt  d.txt  hyderbad  layout  new.txt  prwatech  p.txt  rajkumar 

banglore  c.txt       delhi     dumy   kerala    lin     poi      prwa.txt  q.txt  r.txt 

 

Output:  

a.txt     corona.txt  Data.txt  d.txt  hyderbad  layout  new.txt  prwatech  p.txt  r.txt 

banglore  c.txt       delhi     dumy   kerala    lin     poi      prwa.txt  q.txt 

 

 

  1. To remove directory forcefully(in some case the directory is not deleting use this) 

careful while using this command it will delete forcefully 

 

now we will remove kerala directory 

Command: 

 

rm  -rf

 

 

Operation:   

 

rm  -rf kerala

 

 

Before: 

a.txt     corona.txt  Data.txt  d.txt  hyderbad  layout  new.txt  prwatech  p.txt  r.txt 

banglore  c.txt       delhi     dumy   kerala    lin     poi      prwa.txt  q.txt 

 

Output:  

 

a.txt     corona.txt  Data.txt  d.txt  layout  new.txt  prwatech  p.txt  r.txt 

banglore  c.txt       delhi     dumy   lin     poi      prwa.txt  q.txt 

 

 

 

  1. To remove all any  extension 

 

Operation: 

 

rm    *.txt

 

 

Before: 

x   x.txt  y   y.txt   z   z.txt 

 

Output:  

x  y  z 

 

 

  1. To remove the all the objects from the directory 

Operation:

 

rm   *

 

 

Before: 

bye.txt    hello.txt   x  y  z 

Output:  

x  y  z 

You may get error saying that 

rm: cannot remove ‘x’: Is a directory 

rm: cannot remove ‘y’: Is a directory 

rm: cannot remove ‘z’: Is a directory 

Caution: if you type rm –r you may get error be careful with syntax or command, Linux is case sensitive. 

rm: missing operand 

Try ‘rm –help’ for more information. 

 

 

 

 

 

 

 

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