100 linux useful commands

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linux commands

    Introduction

    We are going to see 100 linux useful commands, that may be handy in case of any trouble shooting or user/admin related activities

    ls – List the contents of a directory

    # ls

    cd – Change the current directory

    # cd Documents

    mkdir – Create a new directory

    mkdir my_directory

    mv – Move or rename a file or directory

    # mv old_file.txt new_file.txt

    cp – Copy a file or directory# cp file1.txt file2.txt

    cp file1.txt file2.txt

    rm – Remove a file or directory

    rm file.txt

    chmod – Change the permissions of a file or directory

    chmod 755 file.txt

    grep – Search for a string in a file

    grep "string" file.txt

    find – Search for files in a directory

    find . -name "*.txt"

    cat – Display the contents of a file

    cat file.txt

    head – Display the first few lines of a file

    head -n 5 file.txt

    tail – Display the last few lines of a file

    tail -n 5 file.txt

    sort – Sort the contents of a file

    sort file.txt

    uniq – Remove duplicate lines from a file

    uniq file.txt

    tar – Create an archive file

    tar -cvf archive.tar file1.txt file2.txt

    gzip – Compress a file

    gzip file.txt

    gunzip – Decompress a file

    gunzip file.txt.gz

    ssh – Connect to a remote computer

    ssh user@host

    scp – Copy files between computers

    scp file.txt user@host:~/

    ping – Test the connection to a remote computer

    ping www.example.com

    ifconfig – Display network configuration

    ifconfig

    route – Display the routing table

    route -n

    netstat – Display network connections

    netstat -an

    top – Display the top running processes

    top

    ps – Display the running processes

    ps -ef

    kill – Terminate a process

    kill -9 1234

    df – Display disk usage

    df -h

    du – Display disk usage of a directory

    du -sh /home/user

    free – Display memory usage

    free -m

    wget – Download a file from the internet

    wget http://example.com/file.zip

    curl – Download a file from the internet

    curl -O http://example.com/file.zip

    apt-get – Install a package

    apt-get install package

    yum – Install a package

    yum install package

    systemctl – Manage system services

    systemctl start service

    service – Manage system services

    service service start

    reboot – Reboot the system

    reboot

    shutdown – Shutdown the system

    shutdown -h now

    date – Display the current date and time

    date

    cal – Display a calendar

    cal

    whoami – Display the current user

    whoami

    passwd – Change the current user’s password

    passwd

    su – Switch to another user

    su user

    sudo – Execute a command as another user

    sudo command

    vi – Edit a file

    vi file.txt

    nano – Edit a file

    nano file.txt

    grep – Search for a string in a file

    grep "string" file.txt

    awk – Process text

    awk '{print $1}' file.txt

    sed – Process text

    sed 's/old/new/g' file.txt

    tr – Translate characters

    tr '[a-z]' '[A-Z]' < file.txt

    diff – Compare two files

    diff file1.txt file2.txt

    patch – Apply a patch to a file

    patch file.txt patch.diff

    ln – Create a symbolic link

    ln -s file.txt link.txt

    chown – Change the owner of a file

    chown user file.txt

    chgrp – Change the group of a file

    chgrp group file.txt

    touch – Create an empty file

    touch file.txt

    echo – Print a string

    echo "Hello World"

    printf – Print a formatted string

    printf "Hello %s\n" World

    bc – Perform calculations

    echo "2+2" | bc

    history – Display the command history

    history

    man – Display the manual page for a command

    man ls

    which – Display the path of a command

    which ls

    type – Display the type of a command

    type ls

    alias – Create an alias for a command

    alias ll='ls -l'

    unalias – Remove an alias

    unalias ll

    export – Set an environment variable

    export PATH=$PATH:/usr/local/bin

    env – Display the environment variables

    env

    echo – Display the value of an environment variable

    echo $PATH

    source – Execute a script in the current shell

    source script.sh

    ssh-keygen – Generate an SSH key

    ssh-keygen -t rsa -b 4096

    ssh-copy-id – Copy an SSH key to a remote computer

    ssh-copy-id user@host

    rsync – Synchronize files between computers

    rsync -avz user@host:/home/user/ ~/

    nc – Network connection tool

    nc -l -p 8080

    telnet – Connect to a remote computer

    telnet host 80

    w – Display who is logged in

    w

    uptime – Display the system uptime

    uptime

    last – Display the last logged in users

    last

    lsof – List open files

    lsof -i

    netcat – Network connection tool

    nc -l -p 8080

    iptables – Configure the firewall

    iptables -A INPUT -p tcp --dport 80 -j ACCEPT

    dig – Query DNS

    dig example.com

    nslookup – Query DNS

    nslookup example.com

    host – Query DNS

    host example.com

    traceroute – Trace the route to a remote host

    traceroute example.com

    nmap – Scan a network

    nmap -sV example.com

    tmux – Multiplex terminal sessions

    tmux

    screen – Multiplex terminal sessions

    screen

    nohup – Run a command in the background

    nohup command &

    crontab – Schedule a command to run periodically

    crontab -e

    at – Schedule a command to run once

    at now + 1 hour

    watch – Execute a command periodically

    watch -n 10 ls

    dd – Copy a file

    dd if=file.txt of=file.bak

    tee – Redirect output to multiple files

    ls | tee file1.txt file2.txt

    ntpd – Synchronize the system clock

    ntpd -q

    logrotate – Rotate log files

    logrotate -f /etc/logrotate.conf

    rdate – Synchronize the system clock

    rdate -s time.example.com

    ntpdate – Synchronize the system clock

    ntpdate -u time.example.com

    chkconfig – Manage system services

    chkconfig --list

    system-config-services – Manage system services

    system-config-services

    iwconfig – Configure wireless network

    iwconfig wlan0 essid "My Network"

    iwlist – Scan for wireless networks

    iwlist wlan0 scan

    Conclusion

    There are lot more commands in linux, this is just basics people who are looking for basic commands quick through, let us know your thoughts and inputs

    Aslo read:

    Veritas Volume Manager (VxVM) cheatsheet – https://computercarriage.com/2023/03/02/veritas-volume-manager-vxvm-cheatsheet/

    Troubleshooting commands in Linux – https://computercarriage.com/2023/02/16/troubleshooting-commands-in-linux/

    block devices using lsblk – https://computercarriage.com/2020/05/18/list-block-devices-using-lsblk-command/

    tldp.org – https://tldp.org/LDP/abs/html/basic.html

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