600 Essential Linux Commands to Solve 99% of Everyday Tasks

1. Basic Commands

uname -m    Show the machine's processor architecture</code>
<code>uname -r    Display the kernel version in use</code>
<code>dmidecode -q    Show hardware system components (SMBIOS/DMI)</code>
<code>hdparm -i /dev/hda    List a disk's architectural features</code>
<code>hdparm -tT /dev/sda    Perform a test read on the disk</code>
<code>arch    Show the machine's processor architecture</code>
<code>cat /proc/cpuinfo    Display CPU information</code>
<code>cat /proc/interrupts    Show interrupt statistics</code>
<code>cat /proc/meminfo    Verify memory usage</code>
<code>cat /proc/swaps    List active swap devices</code>
<code>cat /proc/version    Show the kernel version</code>
<code>cat /proc/net/dev    Show network adapters and statistics</code>
<code>cat /proc/mounts    List mounted file systems</code>
<code>lspci -tv    List PCI devices</code>
<code>lsusb -tv    Show USB devices</code>
<code>date    Show the system date</code>
<code>cal 2007    Show the calendar for the year 2007</code>
<code>date 041217002007.00    Set date and time (MMDDhhmmYY.ss)</code>
<code>clock -w    Save the current time to the BIOS</code>

<h2>2. Shutdown and Reboot</h2>
<pre><code>shutdown -h now    Power off the system (method 1)</code>
<code>init 0    Power off the system (method 2)</code>
<code>telinit 0    Power off the system (method 3)</code>
<code>shutdown -h HH:MM    Schedule a shutdown at a specific time</code>
<code>shutdown -c    Cancel a scheduled shutdown</code>
<code>shutdown -r now    Reboot the system (method 1)</code>
<code>reboot    Reboot the system (method 2)</code>
<code>logout    Log out of the current session</code>

<h2>3. Files and Directories</h2>
<pre><code>cd /home    Enter the /home directory</code>
<code>cd ..    Go up one directory level</code>
<code>cd ../..    Go up two directory levels</code>
<code>cd    Go to the user's home directory</code>
<code>cd ~user1    Go to user1's home directory</code>
<code>cd -    Return to the previous directory</code>
<code>pwd    Show the current working directory</code>
<code>ls    List files in the current directory</code>
<code>ls -F    List files with type indicators</code>
<code>ls -l    Show detailed information for files and directories</code>
<code>ls -a    Show hidden files</code>
<code>ls *[0-9]*    List files and directories containing numbers</code>
<code>tree    Display a tree view of files and directories from the root</code>
<code>lstree    Alternative command for tree view</code>
<code>mkdir dir1    Create a directory named dir1</code>
<code>mkdir dir1 dir2    Create two directories simultaneously</code>
<code>mkdir -p /tmp/dir1/dir2    Create a nested directory tree</code>
<code>rm -f file1    Force delete file1</code>
<code>rmdir dir1    Remove an empty directory named dir1</code>
<code>rm -rf dir1    Recursively delete dir1 and its contents</code>
<code>rm -rf dir1 dir2    Recursively delete two directories</code>
<code>mv dir1 new_dir    Rename or move a directory</code>
<code>cp file1 file2    Copy a file</code>
<code>cp dir/* .    Copy all files from a directory to the current directory</code>
<code>cp -a /tmp/dir1 .    Archive-copy a directory to the current location</code>
<code>cp -a dir1 dir2    Archive-copy a directory</code>
<code>ln -s file1 lnk1    Create a symbolic link to file1 named lnk1</code>
<code>ln file1 lnk1    Create a hard link to file1 named lnk1</code>
<code>touch -t 0712250000 file1    Change a file's timestamp (YYMMDDhhmm)</code>
<code>file file1    Output the MIME type of file1</code>
<code>iconv -l    List known encodings</code>
<code>iconv -f fromEncoding -t toEncoding inputFile > outputFile    Convert file encoding</code>
<code>find . -maxdepth 1 -name *.jpg -print -exec convert "{}" -resize 80x60 "thumbs/{}" \;    Batch resize images in the current directory

4. File Search

find / -name file1    Search for file1 starting from the root</code>
<code>find / -user user1    Find files owned by user1</code>
<code>find /home/user1 -name \*.bin    Search for files ending with .bin in /home/user1</code>
<code>find /usr/bin -type f -atime +100    Find executable files not accessed in the last 100 days</code>
<code>find /usr/bin -type f -mtime -10    Find files created or modified within the last 10 days</code>
<code>find / -name \*.rpm -exec chmod 755 '{}' \;    Find .rpm files and set permissions to 755</code>
<code>find / -xdev -name \*.rpm    Find .rpm files while ignoring removable devices</code>
<code>locate \*.ps    Locate files ending with .ps (run updatedb first)</code>
<code>whereis halt    Show locations of the binary, source, and man page for halt</code>
<code>which halt    Show the full path of the halt executable

5. Mounting a File System

mount /dev/hda2 /mnt/hda2    Mount the partition hda2 (ensure /mnt/hda2 exists)</code>
<code>umount /dev/hda2    Unmount the partition hda2 (ensure no processes are using it)</code>
<code>fuser -km /mnt/hda2    Force unmount when the device is busy</code>
<code>umount -n /mnt/hda2    Unmount without writing to /etc/mtab (useful for read‑only media)</code>
<code>mount /dev/fd0 /mnt/floppy    Mount a floppy disk</code>
<code>mount /dev/cdrom /mnt/cdrom    Mount a CD-ROM or DVD-ROM</code>
<code>mount /dev/hdc /mnt/cdrecorder    Mount a CD‑RW or DVD‑ROM</code>
<code>mount -o loop file.iso /mnt/cdrom    Mount an ISO image file</code>
<code>mount -t vfat /dev/hda5 /mnt/hda5    Mount a Windows FAT32 file system</code>
<code>mount /dev/sda1 /mnt/usbdisk    Mount a USB flash drive</code>
<code>mount -t smbfs -o username=user,password=pass //WinClient/share /mnt/share    Mount a Windows network share

6. Disk Space

df -h    Show mounted partitions with human‑readable sizes</code>
<code>ls -lSr | more    List files sorted by size (smallest first)</code>
<code>du -sh dir1    Estimate the disk usage of dir1</code>
<code>du -sk * | sort -rn    List files and directories sorted by size (largest first)</code>
<code>rpm -q -a --qf '%10{SIZE}t%{NAME}n' | sort -k1,1n    List installed RPM packages sorted by size (Fedora/RedHat)</code>
<code>dpkg-query -W -f='${Installed-Size;10}t${Package}n' | sort -k1,1n    List installed DEB packages sorted by size (Debian/Ubuntu)

7. Users and Groups

groupadd group_name    Create a new user group</code>
<code>groupdel group_name    Delete a user group</code>
<code>groupmod -n new_group_name old_group_name    Rename a user group</code>
<code>useradd -c "Name Surname" -g admin -d /home/user1 -s /bin/bash user1    Create a user belonging to the admin group</code>
<code>useradd user1    Create a new user</code>
<code>userdel -r user1    Delete a user and remove its home directory</code>
<code>usermod -c "User FTP" -g system -d /ftp/user1 -s /bin/nologin user1    Modify user attributes</code>
<code>passwd    Change a password (root only)</code>
<code>passwd user1    Change password for user1</code>
<code>chage -E 2005-12-31 user1    Set password expiration date</code>
<code>pwck    Verify /etc/passwd syntax and integrity</code>
<code>grpck    Verify /etc/group syntax and integrity</code>
<code>newgrp group_name    Switch to a new primary group

8. File Permissions

ls -lh    Show permissions in a human‑readable format</code>
<code>chmod ugo+rwx directory1    Grant read, write, and execute to user, group, and others</code>
<code>chmod go-rwx directory1    Remove read, write, and execute from group and others</code>
<code>chown user1 file1    Change file owner</code>
<code>chown -R user1 directory1    Recursively change ownership</code>
<code>chgrp group1 file1    Change file group</code>
<code>chown user1:group1 file1    Change both owner and group</code>
<code>find / -perm -u+s    List files with the SUID bit set</code>
<code>chmod u+s /bin/file1    Set the SUID bit on a binary</code>
<code>chmod u-s /bin/file1    Remove the SUID bit</code>
<code>chmod g+s /home/public    Set the SGID bit on a directory</code>
<code>chmod g-s /home/public    Remove the SGID bit</code>
<code>chmod o+t /home/public    Set the sticky bit on a directory</code>
<code>chmod o-t /home/public    Remove the sticky bit</code>
<code>chmod +x path    Add execute permission for all</code>
<code>chmod -x path    Remove execute permission for all</code>
<code>chmod u+x path    Add execute permission for the owner</code>
<code>chmod g+x path    Add execute permission for the group</code>
<code>chmod o+x path    Add execute permission for others</code>
<code>chmod ug+x path    Add execute permission for owner and group</code>
<code>chmod =wx path    Grant write and execute, remove read for everyone</code>
<code>chmod ug=wx path    Grant write and execute to owner and group, remove read

9. Special File Attributes

Use “+” to set an attribute and “-” to clear it.

chattr +a file1    Allow only append operations</code>
<code>chattr +c file1    Enable automatic compression/decompression by the kernel</code>
<code>chattr +d file1    Exclude the file from dump backups</code>
<code>chattr +i file1    Make the file immutable (cannot be deleted, renamed, or linked)</code>
<code>chattr +s file1    Securely delete the file</code>
<code>chattr +S file1    Force synchronous writes after each write operation</code>
<code>chattr +u file1    Allow recovery of a deleted file</code>
<code>lsattr    Display special attributes

10. Archiving and Compression

bunzip2 file1.bz2    Decompress a .bz2 file</code>
<code>bzip2 file1    Compress a file using bzip2</code>
<code>gunzip file1.gz    Decompress a .gz file</code>
<code>gzip file1    Compress a file using gzip</code>
<code>gzip -9 file1    Compress with maximum compression</code>
<code>rar a file1.rar test_file    Create a .rar archive</code>
<code>rar a file1.rar file1 file2 dir1    Add multiple files and a directory to a .rar archive</code>
<code>rar x file1.rar    Extract a .rar archive</code>
<code>unrar x file1.rar    Extract a .rar archive</code>
<code>tar -cvf archive.tar file1    Create an uncompressed tarball</code>
<code>tar -tvf archive.tar    List contents of a tarball</code>
<code>tar -xvf archive.tar    Extract a tarball</code>
<code>tar -xvf archive.tar -C /tmp    Extract to /tmp</code>
<code>tar -cvfj archive.tar.bz2 dir1    Create a bzip2‑compressed tarball</code>
<code>tar -xvfj archive.tar.bz2    Extract a bzip2‑compressed tarball</code>
<code>tar -cvfz archive.tar.gz dir1    Create a gzip‑compressed tarball</code>
<code>tar -xvfz archive.tar.gz    Extract a gzip‑compressed tarball</code>
<code>zip file1.zip file1    Create a zip archive</code>
<code>zip -r file1.zip file1 file2 dir1    Recursively add files and directories to a zip archive</code>
<code>unzip file1.zip    Extract a zip archive

11. RPM Packages (Fedora/RedHat)

rpm -ivh package.rpm    Install an RPM package</code>
<code>rpm -ivh --nodeps package.rpm    Install ignoring dependency warnings</code>
<code>rpm -U package.rpm    Upgrade a package without changing config files</code>
<code>rpm -F package.rpm    Refresh an already‑installed package</code>
<code>rpm -e package.rpm    Remove an RPM package</code>
<code>rpm -qa    List all installed RPM packages</code>
<code>rpm -qa | grep httpd    Find installed packages containing "httpd"</code>
<code>rpm -qi package_name    Show detailed information about a package</code>
<code>rpm -qg "System Environment/Daemons"    List packages belonging to a component group</code>
<code>rpm -ql package_name    List files provided by an installed package</code>
<code>rpm -qc package_name    List configuration files of a package</code>
<code>rpm -q package_name --whatrequires    Show packages that depend on this package</code>
<code>rpm -q package_name --whatprovides    Show what this package provides</code>
<code>rpm -q package_name --scripts    Show install/remove scripts</code>
<code>rpm -q package_name --changelog    Show the package changelog</code>
<code>rpm -qf /etc/httpd/conf/httpd.conf    Find which package owns a file</code>
<code>rpm -qp package.rpm -l    List files in an uninstalled RPM</code>
<code>rpm --import /media/cdrom/RPM-GPG-KEY    Import a GPG key</code>
<code>rpm --checksig package.rpm    Verify package signature</code>
<code>rpm -V package_name    Verify file size, permissions, type, owner, MD5, timestamps</code>
<code>rpm -Va    Verify all installed RPMs (use with caution)</code>
<code>rpm -Vp package.rpm    Verify an uninstalled RPM</code>
<code>rpm2cpio package.rpm | cpio --extract --make-directories *bin*    Extract an executable from an RPM</code>
<code>rpm -ivh /usr/src/redhat/RPMS/`arch`/package.rpm    Install a built RPM from source</code>
<code>rpmbuild --rebuild package.src.rpm    Rebuild an RPM from source

12. YUM Package Manager (Fedora/RedHat)

yum install package_name    Download and install an RPM package</code>
<code>yum localinstall package.rpm    Install an RPM using local repositories to resolve dependencies</code>
<code>yum update package_name.rpm    Update all installed RPMs</code>
<code>yum update package_name    Update a specific package</code>
<code>yum remove package_name    Remove an RPM package</code>
<code>yum list    List all installed packages</code>
<code>yum search package_name    Search for a package in repositories</code>
<code>yum clean packages    Remove downloaded package files</code>
<code>yum clean headers    Remove header files</code>
<code>yum clean all    Clean all cached data

13. DEB Packages (Debian/Ubuntu)

dpkg -i package.deb    Install or upgrade a DEB package</code>
<code>dpkg -r package_name    Remove a DEB package</code>
<code>dpkg -l    List all installed DEB packages</code>
<code>dpkg -l | grep httpd    Find installed packages containing "httpd"</code>
<code>dpkg -s package_name    Show status information for a package</code>
<code>dpkg -L package_name    List files installed by a package</code>
<code>dpkg --contents package.deb    List contents of an uninstalled DEB</code>
<code>dpkg -S /bin/ping    Find which package provides a file</code>
<code>apt-get install package_name    Install or upgrade a DEB package</code>
<code>apt-cdrom install package_name    Install from a CD-ROM</code>
<code>apt-get update    Refresh package lists</code>
<code>apt-get upgrade    Upgrade all installed packages</code>
<code>apt-get remove package_name    Remove a DEB package</code>
<code>apt-get check    Verify that package dependencies are satisfied</code>
<code>apt-get clean    Clean the local repository of retrieved package files</code>
<code>apt-cache search term    Search package names and descriptions

14. Viewing File Contents

cat file1    Display the contents of a file</code>
<code>tac file1    Display a file in reverse line order</code>
<code>more file1    Page through a long file</code>
<code>less file1    Page through a file with forward and backward navigation</code>
<code>head -2 file1    Show the first two lines of a file</code>
<code>tail -2 file1    Show the last two lines of a file</code>
<code>tail -f /var/log/messages    Follow a file as it grows (e.g., logs)

15. Text Processing

cat file1 file2 ... | command > file1_out.txt    Pipe files through a command and redirect output</code>
<code>cat file1 | sed 's/string1/string2/g' > result.txt    Replace all occurrences of string1 with string2</code>
<code>grep Aug /var/log/messages    Search for the keyword "Aug" in a log file</code>
<code>grep ^Aug /var/log/messages    Find lines starting with "Aug"</code>
<code>grep [0-9] /var/log/messages    Find lines containing digits</code>
<code>grep Aug -R /var/log/*    Recursively search for "Aug" in /var/log</code>
<code>sed '/^$/d' example.txt    Delete all blank lines</code>
<code>sed '/ *#/d; /^$/d' example.txt    Delete comments and blank lines</code>
<code>tr '[:lower:]' '[:upper:]'    Convert lower‑case to upper‑case</code>
<code>awk 'NR%2==1' example.txt    Print odd‑numbered lines</code>
<code>awk '{print $1}'    Print the first column</code>
<code>paste file1 file2    Merge two files column‑wise</code>
<code>sort file1 file2 | uniq    Show unique lines</code>
<code>comm -1 file1 file2    Show lines unique to file2

16. Character Set Conversion

dos2unix filedos.txt fileunix.txt    Convert a file from DOS to UNIX line endings</code>
<code>unix2dos fileunix.txt filedos.txt    Convert a file from UNIX to DOS line endings</code>
<code>recode ..HTML < page.txt > page.html    Convert a text file to HTML</code>
<code>recode -l    List all supported conversions

17. File System Checks

badblocks -v /dev/hda1    Scan for bad blocks on a disk</code>
<code>fsck /dev/hda1    Check and repair a Linux file system</code>
<code>fsck.ext2 /dev/hda1    Check/repair an ext2 file system</code>
<code>e2fsck -j /dev/hda1    Check/repair an ext3 file system (with journal)</code>
<code>fsck.vfat /dev/hda1    Check/repair a FAT file system

18. Initializing a File System

mkfs /dev/hda1    Create a generic file system</code>
<code>mke2fs /dev/hda1    Create an ext2 file system</code>
<code>mke2fs -j /dev/hda1    Create an ext3 (journaled) file system</code>
<code>mkfs -t vfat -F 32 /dev/hda1    Create a FAT32 file system</code>
<code>fdformat -n /dev/fd0    Format a floppy disk</code>
<code>mkswap /dev/hda3    Create a swap area

19. Swap File System

mkswap /dev/hda3    Create a swap partition</code>
<code>swapon /dev/hda3    Enable a swap partition</code>
<code>swapon /dev/hda2 /dev/hdb3    Enable two swap partitions

20. Backup

dump -0aj -f /tmp/home0.bak /home    Full backup of /home</code>
<code>dump -1aj -f /tmp/home0.bak /home    Interactive backup of /home</code>
<code>restore -if /tmp/home0.bak    Restore an interactive backup</code>
<code>rsync -rogpav --delete /home /tmp    Synchronize two directories</code>
<code>rsync -az -e ssh --delete user@host:/home/public /home/local    Sync remote to local via SSH with compression</code>
<code>dd if=/dev/sda of=/tmp/file1    Copy raw disk data to a file</code>
<code>tar -Puf backup.tar /home/user    Incremental backup of a directory</code>
<code>( cd /tmp/local && tar c . ) | ssh -C user@host "cd /home/share && tar x -p"    Copy a directory to a remote host over SSH</code>
<code>tar cf - . | (cd /tmp/backup ; tar xf - )    Copy a directory locally while preserving permissions</code>
<code>find /home/user1 -name '*.txt' | xargs cp -av --target-directory=/home/backup/ --parents    Find and copy all .txt files preserving directory structure</code>
<code>dd if=/dev/hda of=/dev/fd0 bs=512 count=1    Copy the MBR to a floppy</code>
<code>dd if=/dev/fd0 of=/dev/hda bs=512 count=1    Restore the MBR from a floppy

21. Optical Discs

cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force    Blank a rewritable CD</code>
<code>mkisofs /dev/cdrom > cd.iso    Create an ISO image of a disc</code>
<code>mkisofs -J -allow-leading-dots -R -V "Label CD" -iso-level 4 -o ./cd.iso data_cd    Create an ISO with volume label</code>
<code>cdrecord -v dev=/dev/cdrom cd.iso    Burn an ISO image to CD</code>
<code>mount -o loop cd.iso /mnt/iso    Mount an ISO image</code>
<code>cd-paranoia -B    Rip audio tracks from a CD to WAV files</code>
<code>dd if=/dev/hdc | md5sum    Compute MD5 checksum of a CD

22. Network

ifconfig eth0    Show Ethernet interface configuration</code>
<code>ifup eth0    Bring up the eth0 interface</code>
<code>ifdown eth0    Bring down the eth0 interface</code>
<code>ifconfig eth0 192.168.1.1 netmask 255.255.255.0    Set static IP address</code>
<code>ifconfig eth0 promisc    Enable promiscuous mode for packet sniffing</code>
<code>dhclient eth0    Obtain an IP address via DHCP</code>
<code>route -n    Show the routing table</code>
<code>route add -net 0/0 gw IP_Gateway    Add a default gateway</code>
<code>route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1    Add a static route</code>
<code>echo "1" > /proc/sys/net/ipv4/ip_forward    Enable IP forwarding</code>
<code>hostname    Show the system hostname</code>
<code>host www.example.com    Resolve a hostname to an IP address</code>
<code>nslookup www.example.com    DNS lookup</code>
<code>ip link show    Show status of all network interfaces</code>
<code>netstat -tup    Show active TCP/UDP connections with PIDs</code>
<code>tcpdump tcp port 80    Capture HTTP traffic</code>
<code>iwlist scan    Scan for wireless networks</code>
<code>whois www.example.com    Query the WHOIS database

23. Listing Directory Contents

ls -a    Show all files, including hidden ones</code>
<code>ls -l    Show detailed file information</code>
<code>ls -R    Recursively list sub‑directories</code>
<code>ls -ld    Show directory and link information</code>
<code>pwd    Print the current working directory

24. Determine File Type

file file1    Identify the file type

25. Copying Files and Directories

cp source destination    Copy a file or directory</code>
<code>cp -r source_dir dest_dir    Recursively copy a directory tree</code>
<code>touch file1    Create an empty file or update its timestamp</code>
<code>mv old_name new_name    Rename or move a file/directory</code>
<code>rm -f file1    Force delete a file</code>
<code>rmdir dir1    Remove an empty directory</code>
<code>rm -rf dir1    Recursively delete a directory and its contents

26. Common System Commands

date    Show or set the current date and time</code>
<code>hwclock    Show the hardware clock (requires root)</code>
<code>cal    Display a calendar</code>
<code>uptime    Show how long the system has been running</code>
<code>echo "text"    Print text to the terminal or a file</code>
<code>cat file    Display file contents</code>
<code>head -n file    Show the first n lines of a file</code>
<code>tail -n file    Show the last n lines of a file</code>
<code>tail -f file    Follow a file as it grows</code>
<code>more file    Page forward through a file</code>
<code>less file    Page forward and backward through a file</code>
<code>iostat, vmstat, free, dmesg    Various system diagnostics

27. VIM Editor

VIM is a powerful command‑line text editor. Launch it with vim followed by a file path. If the file exists, it opens for editing; otherwise, a new file is created. :q Quit VIM VIM has three modes:

Command mode – default mode for navigation and issuing commands.

Insert mode – press i to insert text; press Esc to return to command mode.

Ex mode – press : to enter command‑line mode for saving, quitting, etc.

Common command‑mode shortcuts: i – Insert before the cursor. o – Open a new line below. dd – Delete the current line. yy – Yank (copy) the current line. nyy – Yank n lines. p – Paste after the cursor. u – Undo the last change. /pattern – Search for a pattern.

Ex‑mode commands: :w – Write (save) changes. :q – Quit. :q! – Quit without saving. :x – Save and quit (equivalent to :wq). :set number – Show line numbers. :! command – Execute a shell command. :sh – Drop to a shell; Ctrl‑D returns to VIM.

28. RPM Package Management Commands

rpm -ivh package.rpm    Install a package (show progress with #)</code>
<code>rpm -e package    Remove a package (does not delete modified config files)</code>
<code>rpm -Uvh package.rpm    Upgrade a package to a newer version</code>
<code>rpm -Fvh package.rpm    Refresh (reinstall) a package</code>
<code>rpm -q package    Query information about an installed package</code>
<code>rpm -ql package    List files installed by a package

29. Additional Notes

The article concludes with a reminder to follow the author’s public account for updates and to give the post a like.