File Management Commands 📂

ls

Description: Lists directory contents.

• Usage:

ls          # Lists files and directories in the current directory
ls -l       # Lists files with detailed information
ls -a       # Lists all files including hidden files

cd

Description: Changes the current directory.

• Usage:

    cd /path/to/directory  # Changes to the specified directory
    cd ..                  # Moves up one directory level
    cd ~                   # Changes to the home directory
  

pwd

Description: Prints the current working directory.

• Usage:

    pwd  # Displays the full path of the current directory
  

mkdir

Description: Creates a new directory.

• Usage:

    mkdir new_directory        # Creates a new directory named 'new_directory'
    mkdir -p /path/to/new_dir  # Creates a nested directory structure
  

  rm, rmdir

  Description: Deletes files and directories.

• Usage:

    rm file_name              # Deletes a file
    rm -r directory_name      # Recursively deletes a directory and its contents
    rmdir directory_name      # Deletes an empty directory
  

  cp

  Description: Copies files and directories.

• Usage:

cp source_file destination_file        # Copies a file
cp -r source_directory destination_directory  # Copies a directory recursively

mv

Description: Moves or renames files and directories.

• Usage:

    mv old_name new_name               # Renames a file or directory
    mv file_name /path/to/destination  # Moves a file to a new location
  

  touch

  Description: Creates an empty file or updates the timestamp of an existing file.

• Usage:

    touch new_file   # Creates an empty file named 'new_file' or updates its timestamp
  

  ln (hard link, soft link)

  Description: Creates hard and symbolic (soft) links.

Usage:

ln source_file link_name               # Creates a hard link
ln -s source_file soft_link_name       # Creates a symbolic link

Viewing and Editing Files 📜

cat, zcat

Description: Concatenates and displays file content.

• Usage:

    cat file_name       # Displays the content of a file
    zcat file_name.gz   # Displays the content of a compressed file
  

  head

  Description: Outputs the first part of a file.

• Usage:

    head file_name         # Displays the first 10 lines of a file
    head -n 5 file_name    # Displays the first 5 lines of a file
  

  tail, tail -f

  Description: Outputs the last part of a file.

• Usage:

    tail file_name         # Displays the last 10 lines of a file
    tail -f file_name      # Continuously monitors a file for new lines
  

  less, more

  Description: Views file content one screen at a time.

• Usage:

    less file_name   # Opens a file for viewing
    more file_name   # Opens a file for viewing, but with fewer features than 'less'
  

  vi editor

  Description: Opens the vi text editor.

Usage:

vi file_name       # Opens a file in the `vi` editor
# In `vi`, use 'i' to enter insert mode, 'Esc' to exit insert mode, ':w' to save, and ':q' to quit

System Information and Management 🖥️

ps

Description: Reports a snapshot of current processes.

• Usage:

    ps       # Displays a snapshot of current processes
    ps aux   # Displays detailed information about all running processes
  

  top

  Description: Displays real-time system information including processes.

• Usage:

    top   # Starts the top command
  

  df

  Description: Reports file system disk space usage.

• Usage:

    df       # Displays disk space usage for all mounted filesystems
    df -h    # Displays disk space usage in human-readable format
  

  du

  Description: Estimates file and directory space usage.

• Usage:

    du directory_name    # Displays the disk usage of a directory and its contents
    du -sh directory_name  # Displays the disk usage in human-readable format
  

  free

  Description: Displays the amount of free and used memory in the system.

• Usage:

    free       # Displays memory usage
    free -h    # Displays memory usage in human-readable format
  

  vmstat

  Description: Reports virtual memory statistics.

• Usage:

    vmstat    # Displays a summary of system performance
  

  Networking Commands 🌐

  ssh

  Description: Connects to a remote machine securely.

• Usage:

    ssh user@hostname       # Connects to a remote machine
    ssh user@hostname -p port_number  # Connects to a remote machine on a specific port
  

  Process Management 🔧

  fuser

  Description: Identifies processes using files or sockets.

• Usage:

    fuser file_name   # Displays processes using the specified file
  

  kill

  Description: Sends a signal to a process, usually to terminate it.

• Usage:

    kill PID             # Sends the default TERM signal to a process
    kill -9 PID          # Forcefully terminates a process
  

  nohup

  Description: Runs a command immune to hangups, with output to a non-tty.

• Usage:

    nohup command &   # Runs 'command' in the background, immune to hangups
  

  Miscellaneous Commands 📊

  cut

  Description: Removes sections from each line of files.

• Usage:

    cut -d',' -f1 file_name   # Cuts the first field from a comma-delimited file
  

  tee

  Description: Reads from standard input and writes to standard output and files.

• Usage:

    command | tee file_name  # Writes the output of 'command' to 'file_name' and to the terminal
  

  sort

  Description: Sorts lines of text files.

• Usage:

    sort file_name      # Sorts a file alphabetically
    sort -n file_name   # Sorts a file numerically
  

  clear

  Description: Clears the terminal screen.

• Usage:

    clear   # Clears the terminal
  

  diff

  Description: Compares files line by line.

• Usage:

    diff file1 file2   # Shows the differences between 'file1' and 'file2'
  

  wc

  Description: Word, line, character, and byte count for files.

• Usage:

    wc file_name       # Displays line, word, and byte counts
    wc -l file_name    # Displays line count