Linux Commands part - 2

$file images.png

output-

Dimensions file type 8 bit color map

$less file.txt

this command shows overwhelm text in one screen at a time.

$sudo apt install imagemagick

$identify images.png

Gives the properties of the images etc...

$mkdir -p /home/Desktop/maverick/Documents/MyDocuments/

This command gonna create sub-directory.

$ mkdir -p Soumya/Documents/Kali.pdf/ | touch mk.txt

Find

$$ find /home -name puppies.jpg

$$ find /home -type d -name MyFolder

$help

$man

$whatis ls

Oneliner help this command will explain the command in one line.

18. alias

Sometimes typing commands can get really repetitive, or if you need to type a long command many times, it’s best to have an alias you can use for that. To create an alias for a command you simply specify an alias name and set it to the command.

$ alias foobar='ls -la'

Now instead of typing ls -la, you can type foobar and it will execute that command, pretty neat stuff. Keep in mind that this command won't save your alias after reboot, so you'll need to add a permanent alias in:

~/.bashrc

or similar files if you want to have it persist after reboot.

You can remove aliases with the unalias command:

$ unalias foobar

Standard OUTPUT

cat Hello, World! > Data.txt - overwrite

cat Hello, World! Damm >> Data.txt - >> not overwriting

Stdin 

Standard Input

$cat <Data.txt> Data1.txt

Data.txt contains data copy in Data1.txt

$ls <Data.txt> Data1.txt

Data1.txt contains list of files.

$ pwd < Data.txt > Data1.txt

Data1.txt contains current working directory path text.

mkdir wd <c.txt> p.txt

ls -la -o Data.txt

ls -la Data.txt

Standard Error

$ ls /fake/directory 2> /dev/null

For no output file..

Pipe AND Tee

$ ls -la /etc

$ ls -la /etc | less 

$ ls | tee peanuts.txt

You should see the output of ls on your screen and if you open up the peanuts.txt file you should see the same information!

$ ls > info.txt

this will not show info on screen but it will store in info.txt file.

 

 Environment

$echo $HOME

$echo $USER

$env

shows the environment variables.

$echo $PATH

 

Cut Command 

1.

$echo 'Welcome To Delhi. Delhi is the place of dilwale.

$cut -c 2 State.txt

e

Above command extract characters.

$cut -c 5 State.txt

o

 

2. 

$ cut -f 2 -d "." State.txt
Delhi is the place of dilwale
Above commands gives the output after the  delimeter (.).

 

 Paste here hanuman ji message from kali linux machine.

29 FEB 2024

Head & Tail

$head Radha.txt

head -n 15 R.txt

This command gives the first or few lines of text

$tail Radha.txt

This command gives the last few lines of text 

 

Expand u/s Unexpand

1.Expand - converts tabs to spaces.

$expand -t 4 file.txt

$ expand sample.txt > result.txt

2.Unexpand - converts spaces to tabs.

$unexpand -t 4 file.txt

$ unexpand -a result.txt

Sort

$sort f1.txt

sort the text

$sort -r f1.txt - reverse sort the text.

And also sort via numerical value:

$ sort -n file1.txt

bird

cat

cow

elephant

dog

Translate

tr -d "abc" - # Deletes characters a, b, and c

tr -u '[:lower:]' '[:upper:]'  # Translate lowercase to uppercase

tr -l '[:upper:]' '[:lower:]'  # Translate uppercase to lowercase

Examples:

• Translate all uppercase characters to lowercase:

  bash
  echo "HELLO" | tr '[:upper:]' '[:lower:]'
  

• Delete all digits from input:

  bash
  echo "Hello123" | tr -d '[:digit:]'
  

• Replace spaces with tabs:

  bash
  echo "Hello World" | tr ' ' '\t'
  

• Remove all non-alphanumeric characters:

  bash
  echo "Hello, world!" | tr -cd '[:alnum:]'

• echo "maverick" | tr a-z A-Z
• echo a-z A-Z
• maverick
• Maverick

uniq (Unique)

he uniq (unique) command is another useful tool for parsing text.

Let's say you had a file with lots of duplicates:

reading.txt

book

book

paper

paper

article

article

magazine

$ uniq reading.txt

book

paper

article

magazine

$uniq Not_Unique_text.txt 

Anshu

rishu

piyush

ashish

$uniq -d names.txt - just get duplicate values.

wc (Word Count)and nl (Number Lines)

┌──(maverick㉿kali)-[~/Desktop/TXT-FILES]

└─$ wc F1.txt

 3  3 19 F1.txt

#F1.txt contains these three names without numbers Anshu Piyush and Rishu

┌──(maverick㉿kali)-[~/Desktop/TXT-FILES]

└─$ nl F1.txt 

     1 Anshu

     2 Piyush

     3 Rishu

Grep

$ grep Piyush F1.txt

 Debian package and rpm        

           

Install a package Debian: 

$ dpkg -i some_deb_package.deb 

RPM: 

$ rpm -i some_rpm_package.rpm 

The i stands for install. You can also use the longer format of --install. 

Remove a package

Debian: 

$ dpkg -r some_deb_package.deb RPM:

 $ rpm -e some_rpm_package.rpm 

Debian: 

r for remove RPM: e for erase List installed packages 

Debian: $ dpkg -l RPM: $ rpm -qa

User Management

$ cat /etc/shadow - view the protected file

How to create a user in kali linux?

$sudo useradd bob

How to delete user in kali linux?

$sudo userdel bob

2. System V Service

All service commands

There are many command line tools you can use to manage Sys V services.

List services

$ service --status-all

Start a service

$ sudo service networking start

Stop a service

$ sudo service networking stop

Restart a service

$ sudo service networking restart

Permissions

Processes

#linuxcommands