README.md

• whereis - Find the path of that executable file.

List operation

• ls - Shows list.
  • -a - Hidden file.
  • -l - Permission.
  • -R - Show sub dir.

Changing dir operation

• cd <folder-name> - Change Dir.
• cd .. - Go one Directory back.
• cd - Go to home.
• cd ../<foldername> - Open a previous dir folder.
• cd <path> - Open a dir with the path.

File/Folder Ope.

• mkdir <new-dir-name> - Create a new folder.
• mkdir -p test/test1/test2 - Create a dir between two directories.
• touch <new-file-name> - create a blank file.
• pwd - Present working directory.
• cat <filename> - Display file content.
• cat > <new-file-name> - Create a file.
• dd if=/dev/zero of=bos_dosya bs=4G count=1- create empty file with zeros
• cat >> <filename> - Append the file
• cat <filename1> >> <filename2> - Append the content of the file filename1 at the end of the file .
• cat <filename> <filename2> - Display 2 files at a time.
• cat <filename> <filename2> > <newfile-name> - Merge both of file content in a single one.
• cat <file-name> | tr > <new-file-name> - Translate the file.
• cut -c 1-2 <filename> - cut the file column wise
• echo "Hello" >> <file-name>
• man <commad name> - Know about the command usages and options.
• man <commad name> - know about the command.

File/Folder operation

• cp <file-name> <new-fie-name> - Make a copy of a file in the current location.
• mv <file-name> <dir-path> - Move a file from one dir to another.
• mv <file-name> <new-fie-name> - Rename a file.
• mv -R <dir-name> <dir-path> - Move Dir
• rm <file-name> - Remove a file permanently.
• rm -R <file-name> - Delete a folder with dir included.
• head <file-name> - Will display first 10 lines of a file.
• tail <file-name> - Will display last 10 lines of a file. --n 2 - will display last 2 lines.
• diff <file-1> <file-2> - Show diff between the two files.
• locate <file> - To find out the file.
• find <file/folder-name> - Find a file/folder.
• find <dir-name> - Find files inside the dir
• find .-type d - Show only dir.
  • .-type f - show only files.
  • .-type f -name "*.txt" - Show only files with that specific name.
  • .-type f -iname "*.txt" - Show only files with that specific name - not case sensitive (i)
  • .-type f -mmin -20 - Show files which modify less than 20 min ago.
  • .-type f -mmin +20 - show files which modify more than 20 min ago.
  • .-type f -maxdepth 2 - Will only show 1 folder deep.
  • .-size +1k - will only show file/folder with size of 1kb

System commands

• ps aux - processes which are running
• systemctl [option] [service] - interact with a process
  • We can do 4 option with systemctl
    • start
    • stop
    • enable
    • disable
  • Example, systemctl start apache2
• df - Check the capacity and storage details.
  • m - In megabyte or
  • hg - In gigabyte.
• du - Disk usages capcity
  • -h (human readable)
• echo - Get a output of a string
• echo $PATH - Check the path variable
• sudo - Admin command
• sudo chown root text.txt - change owner
• !<command-name> - Run the previous command
• git add .; git commit -m "message" - Run multiple commands at a time
• sort <file-name>" - sort the file
• job - show the jobs
• wget <url> - download the file from the URL
• top - what processes are running
• kill <process-id> -stop that process
• Uname - show the system info
• zip <file-1> <file-2> - Zip Two or more files
• Unzip <file-name> - Unzip files
• useradd <name> - add a user
• passwd <name> - set a password for the user
• uname -<flag> -o -m -r
• lscpu - get cpu details
• free - free memory
• vmstat - virtual memory
• lsof - list all the open file
• xdg-open <file-fath> - open the folder (graphical window) of a file/folder with path.
• xdg-open . - open the folder of the current directory.
• vi ~/.bashrc - set your Alias
• echo -n 'username' | base64 - encode the username to base64
• echo -n 'encoded' | base64 -d - decode the username to base64

Networking

• nslookup google.com - To check the IP address of the domain.
• netstat - To check the network status.
• hostname - To check the hostname.
• whoami - To check the current user.
• ping google.com - To check the connectivity.

Permissions

• chmod u=rwx,g=rxw,o=rwx <file-name> READ, WRITE AND EXECUTE
• chmod 777 <file-name> - 4- Read, 2- Write, 1 - Execute
• find . -perm 777 - shows files with all permissions(rwx)
• grep <keyword> <file-name> - To search if the keyword is presnt in the file or not
• grep -w <keyword> <file-name> - To search if the keyword is present in the file or not (complete word)
• grep -i <keyword> <file-name> - To search if the keyword is present in the file or not (not case sens)
• grep -n <keyword> <file-name> - To search if the keyword is present in the file or not (Line number)
• grep -B <keyword> <file-name> - Show Line before that keyword
• grep -win <keyword> ./*.txt - To search if the keyword is present in the file in current dir
• grep -win -r <keyword> .*
• history | grep "ls -l" - Piping, we filter out the things

history
!<number-from-history>

Operators

• ping google.com & ping facebook.com - run both the commands at the same time
• echo "google.com" && echo "facebook.com" - second will only run if first is successful
• echo "google.com" && {echo "facebook.com"; eco "pradumnasaraf.co"}
• echo "google.com" || echo "pingfacebook.com" - second will only run if first is not successful
• rm -r !(file.txt) - delete all files except file.txt
• printevnv - to print all th env.