Linux Commands DAY 1

Manual

• To help users understand how commands are used in Linux.
• Important " z " & " w " are the KEY.

whoami

• Which is used to print the current userID

hostname

• whereami?
• System's hostname.
• கம்ப்யூட்டருடைய name அவ்வளவுதான் in simple , so that they can communicate with each systems.
• In-dept ( DNS & FQDN )
• எனக்கு இந்த பேர் பிடிக்கல so you can change hostname too.
• sudo hostname
• hostname -I ( Private IP )

date

• current date and time of the system.
• date
• date --date="3 years ago" --> மூணு வருஷத்துக்கு முன்னாடி.
• date --date="tomorrow"
• date --date="next wed"
• date --date="1 year"

ls

• List the directory contents
• "ls -l" --> long listing of files Filesணு சொல்லுவாங்க , that means You will see the file permissions, the number of links, owner name, owner group, file size, time of last modification, and the file or directory name .
• "ls -lh" --> human readable
• "ls -lt" --> newest file at the top.
• "ls -a" --> The -a option displays all files, hidden or otherwise. Some files begin with . or .. and those files are hidden from the user by default.
• "ls -lS" --> Sort by file size ( வகைபடுத்து / arrange )
• "ls -R" --> list directory trees in a long format.

cat

• concatenates files and print on the standard output.
• cat /etc/hosts
• cat /etc/group
• View Multiple files --> cat file1.xt file2.txt
• ஒரு file create பண்ணனும்னா - cat > filename.txt ( write the content which you require ) CONTROL + D , it will be saved.
• more & less --> cat /proc/cpuinfo | less ( to view larger files ) --> spacebar & pagedown ( one page forward ) --> pageup & b ( one page backward ) cat /proc/cpuinfo | more .

history

• list of commands used in the terminal.
• history 10 --> latest command.
• !100
• !! --> last command repeat
• history -d 1356 --> delete
• history -c --> clear the whole history
• history | tail 10 --> last 10 commands

echo

• Displaying lines of text.
• Prints out arguments as the standard output.
• To display text strings or command results as messages.
• echo [string]
• "echo welcome to kaniyam"
• echo "welcome to kaniyam"

rm

• Remove files or directory
• rm file_name
• rm -r --> recursively
• rm -i --> interactively
• rm -f --> forcefully
• rm -f *.txt --> all files

• Above command in the tshirt will crash the complete Linux system - Don't try . It's just to know 😊