Navigating a Linux Computer

Asad Prodhan^*

Q: How to use my Linux computer remotely?

• Open a ssh client. For example, MobaXterm
• Click on ‘Session’ located at top-left corner
• Fill up the following boxes and click ‘OK’:
  • Remote host
  • Specify username
  • SSH-browser type as SFTP protocol

Figure 1: MobaXterm.

Q: How to enable sftp on the sidebar in the MobaXterm?

• Go to MobaXterm Session settings > SSH > Fill up Remote host > Specify username > Select ‘SFTP protocol’ from the ‘SSH-browser type’ drop down menu

Q: How to transfer data between a remote computer and your local laptop?

Option 1: Drag and drop using the left panel of your MobaXterm

Option 2: sftp - sftp username@remotehost:/destinationdirectory - ‘put -r’ to transfer data from local to remote - ‘put -ar’ to transfer data that failed in the first attempt - ‘get -r’ to transfer from remote to local

🐧 Linux Usage Exercise for New User

Welcome to Linux training! This brief guide will help you get started with essential Linux commands and concepts.

📁 1. Working with Directories (i.e. Folders)

Check your current location

pwd

See what you have in your current location

ls

Create a new directory called 'practice'

mkdir practice

Move into the directory

cd practice

Create nested directories

mkdir -p projects/scripts

Go up one directory

cd ..

📄 2. Working with Files

Create a new text file

echo "Hello, Linux!" > hello.txt

View the content

cat hello.txt

Copy the file

cp hello.txt hello_backup.txt

Rename the file

mv hello.txt greetings.txt

Delete the backup

rm hello_backup.txt

🔍 3. Viewing and Searching

View contents of a file

less greetings.txt

Search inside the file

grep "Hello" greetings.txt

List files with details

ls -lh

👥 4. User and Permissions

Check who you are

whoami

See your groups

groups

Check file permissions

ls -l greetings.txt

Change permissions (read/write for user only)

chmod +x greetings.txt

Or,

chmod +x *

⚙️ 5. System Information and Help

View disk usage

df -h

See memory usage

free -h

View running processes

top

Get help on commands

man ls

🧑‍💻 6. Sudo and Package Installation

Update package list

sudo apt update

Install a basic tool (example: tree)

sudo apt install tree

Use the installed tool

tree

✅ 7. Create a Simple Script

Create a script file

nano say_hello.sh

Paste the following content into the file:

```

!/bin/bash

echo "Hello, $USER! Today is $(date)." ```

Then run:

Make it executable

chmod +x say_hello.sh

Execute the script

./say_hello.sh

🚀 You're Ready!

You've just taken your first steps into Linux! Continue experimenting using the following Linux commands to explore further

GREP

| Code/ Symbol | Command/ Elaboration | Function/ Example | |:----------|:----------|:----------| | grep | Search and print lines containing a word | grep 'salmon' File.tsv > FileSalmon.tsv | | grep --color | Search text | grep --color "Lunch" File1.txt | | grep --color -A 2 "word" | Print 2 lines after the match | grep --color -A 2 "word" File1.txt | | grep --color -B 2 "word" | Print 2 lines before the match | grep --color -B 2 "word" File1.txt | | grep --color -C 2 "word" | Print 2 lines before and after the match | grep --color -C 2 "word" File1.txt | | grep -v "word" | Find everything except 'word' | grep -v "word" File1.txt | | grep -c "[WW]ord" | Count the occurrence of 'W/word' | grep -c "[WW]ord" File1.txt |

SED

| Code/ Symbol | Command/ Elaboration | Function/ Example | |:----------|:----------|:----------| | sed -n 3p | Extract the 3rd line | sed -n 3p File1.txt | | sed -n 3-5p | Extract the 3rd to 5th lines | sed -n 3-5p File1.txt | | sed 's/Find/Replace/g' File.txt | Find and replace | sed 's/Ishmael/Dave/g' File1.txt; "Ishmael" replaced by "Dave" |

AWK

| Code/ Symbol | Command/ Elaboration | Function/ Example | |:----------|:----------|:----------| | awk '{print $1,$2,$3,$4,$5,$7}' | Subset columns 1-5, 7 | awk '{print $1,$2,$3,$4,$5,$7}' file.tsv
| awk '{print $3}' | Print third column | awk '{print $3}' File.tsv | | awk '{print $3,"\t"50}' | Print third column and add 50 at reach row; /t is tab space | awk '{print $3,"\t"50}' File.tsv | | awk '{print $3,"\t"$3+1}' | Print third column and add 1 with all row values | awk '{print $3,"\t"$3+1}' File.tsv |

CUT

| Code/ Symbol | Command/ Elaboration | Function/ Example | |:----------|:----------|:----------| | cut -f1,2,3,4,5,7 | Subset columns 1-5, 7 | cut -f1,2,3,4,5,7 File1.txt

NANO

| Code/Symbol | Function/Example |
|:----------|:----------| | alt+sht+$ | wraps lines | | alt+sht+y | highlights syntex | | alt+sht+# | puts line number | | fg | to return to nano | | ctrl+K | deletes entire line | | ctrl+A | moves the cursor at the beginning of the line | | ctrl+E or Alt+/ | moves the cursor at the end of the line | | Ctrl+Shift+- 7406148 | Jump to line number 7406148 | | Ctrl+W | Search for words |

PUTTY

| Code/Symbol | Function/Example |
|:----------|:----------| | psftp> get -r * | download one file | | psftp> mget -r * | download multiple files | | psftp> put -r * | upload one file | | psftp> mput -r * | upload multiple files |

## TMUX

| Code/Symbol | Function/Example |
|:---------- |:----------| | tmux > press enter | start tmux session | | Ctrl-b d | detach from the tmux session but the session will continue running in the background | | tmux list | list all the active tmux sessions. Left-hand column shows the session numbers | | tmux attach -t 1 | logging in into tmux session 1 | | tmux kill-session -t 1 | terminating tmux session 1 |