BOL

Linux Commands Cheat Sheet

    File System

    ls — list items in current directory

    ls -l — list items in current directory and show in long format to see perimissions, size, an modification date

    ls -a — list all items in current directory, including hidden files

    ls -F — list all items in current directory and show directories with a slash and executables with a star

    ls dir — list all items in directory dir

    cd dir — change directory to dir

    cd .. — go up one directory

    cd / — go to the root directory

    cd ~ — go to to your home directory

    cd - — go to the last directory you were just in

    pwd — show present working directory

    mkdir dir — make directory dir

    rm file — remove file

    rm -r dir — remove directory dir recursively

    cp file1 file2 — copy file1 to file2

    cp -r dir1 dir2 — copy directory dir1 to dir2 recursively

    mv file1 file2 — move (rename) file1 to file2

    ln -s file link — create symbolic link to file

    touch file — create or update file

    cat file — output the contents of file

    less file — view file with page navigation

    head file — output the first 10 lines of file

    tail file — output the last 10 lines of file

    tail -f file — output the contents of file as it grows, starting with the last 10 lines

    vim file — edit file

    alias name 'command' — create an alias for a command
    System

    shutdown — shut down machine

    reboot — restart machine

    date — show the current date and time

    whoami — who you are logged in as

    finger user — display information about user

    man command — show the manual for command

    df — show disk usage

    du — show directory space usage

    free — show memory and swap usage

    whereis app — show possible locations of app

    which app — show which app will be run by default
    Process Management

    ps — display your currently active processes

    top — display all running processes

    kill pid — kill process id pid

    kill -9 pid — force kill process id pid
    Permissions

    ls -l — list items in current directory and show permissions

    chmod ugo file — change permissions of file to ugo - u is the user's permissions, g is the group's permissions, and o is everyone else's permissions. The values of u, g, and o can be any number between 0 and 7.

    7 — full permissions

    6 — read and write only

    5 — read and execute only

    4 — read only

    3 — write and execute only

    2 — write only

    1 — execute only

    0 — no permissions

    chmod 600 file — you can read and write - good for files

    chmod 700 file — you can read, write, and execute - good for scripts

    chmod 644 file — you can read and write, and everyone else can only read - good for web pages

    chmod 755 file — you can read, write, and execute, and everyone else can read and execute - good for programs that you want to share
    Networking

    wget file — download a file

    curl file — download a file

    scp user@host:file dir — secure copy a file from remote server to the dir directory on your machine

    scp file user@host:dir — secure copy a file from your machine to the dir directory on a remote server

    scp -r user@host:dir dir — secure copy the directory dir from remote server to the directory dir on your machine

    ssh user@host — connect to host as user

    ssh -p port user@host — connect to host on port as user

    ssh-copy-id user@host — add your key to host for user to enable a keyed or passwordless login

    ping host — ping host and output results

    whois domain — get information for domain

    dig domain — get DNS information for domain

    dig -x host — reverse lookup host

    lsof -i tcp:1337 — list all processes running on port 1337
    Searching

    grep pattern files — search for pattern in files

    grep -r pattern dir — search recursively for pattern in dir

    grep -rn pattern dir — search recursively for pattern in dir and show the line number found

    grep -r pattern dir --include='*.ext — search recursively for pattern in dir and only search in files with .ext extension

    command | grep pattern — search for pattern in the output of command

    find file — find all instances of file in real system

    locate file — find all instances of file using indexed database built from the updatedb command. Much faster than find

    sed -i 's/day/night/g' file — find all occurrences of day in a file and replace them with night - s means substitude and g means global - sed also supports regular expressions
    Compression

    tar cf file.tar files — create a tar named file.tar containing files

    tar xf file.tar — extract the files from file.tar

    tar czf file.tar.gz files — create a tar with Gzip compression

    tar xzf file.tar.gz — extract a tar using Gzip

    gzip file — compresses file and renames it to file.gz

    gzip -d file.gz — decompresses file.gz back to file
    Shortcuts

    ctrl+a — move cursor to beginning of line

    ctrl+f — move cursor to end of line

    alt+f — move cursor forward 1 word

    alt+b — move cursor backward 1 word