The Most Complete Linux Command Cheat Sheet

1. Basic System Commands

uname -m               # display machine architecture
uname -r               # display kernel version
dmidecode -q           # display hardware components
hdparm -i /dev/hda     # list disk characteristics
hdparm -tT /dev/sda    # perform read test on disk
cat /proc/cpuinfo      # show CPU information
cat /proc/interrupts   # show interrupts
cat /proc/meminfo      # show memory usage
cat /proc/swaps        # show swap usage
cat /proc/version      # show kernel version
cat /proc/net/dev      # show network interfaces and statistics
cat /proc/mounts       # show mounted filesystems
lspci -tv              # list PCI devices
lsusb -tv              # list USB devices
date                   # display system date
cal 2007               # display calendar for year 2007
clock -w               # write system time to BIOS

2. Shutdown and Reboot

shutdown -h now               # immediate shutdown
shutdown -r now               # immediate reboot
shutdown -h +10              # shutdown after 10 minutes
shutdown -h 23:30            # shutdown at 23:30
init 0                        # alternative shutdown command
telinit 0                     # alternative shutdown command
shutdown -c                  # cancel scheduled shutdown

3. File and Directory Operations

cd /home                     # change to /home directory
cd ..                        # go up one level
cd ../..                     # go up two levels
cd ~user1                    # change to user1's home directory
cd -                         # return to previous directory
pwd                          # print working directory
ls                           # list files
ls -F                        # list files with type indicators
ls -l                        # detailed list
ls -a                        # include hidden files
ls *[0-9]*                   # list files containing numbers
tree                         # display directory tree
mkdir dir1                   # create directory dir1
mkdir -p /tmp/dir1/dir2      # create nested directories
rm -f file1                  # force delete file1
rm -r dir1                   # recursively delete directory dir1
mv dir1 new_dir               # rename or move directory
cp file1 file2               # copy file1 to file2
cp -a /tmp/dir1 .            # copy directory preserving attributes
ln -s file1 link1            # create symbolic link
ln file1 hardlink1           # create hard link
chmod ugo+rwx directory1     # set read/write/execute for all
chmod go-rwx directory1       # remove group and others permissions
chown user1 file1            # change file owner
chgrp group1 file1           # change file group
chmod +t file1               # set sticky bit

4. File Search

find / -name file1                 # search for file1 from root
find /home/user1 -name "*.bin"    # search for .bin files in a directory
find /usr/bin -type f -atime +100 # files not accessed in last 100 days
find /usr/bin -type f -mtime -10  # files modified in last 10 days
locate *.ps                        # quickly locate files ending with .ps (requires updatedb)
whereis halt                       # locate binary, source, and man page for halt
which halt                         # show full path of executable

5. Mounting Filesystems

mount /dev/hda2 /mnt/hda2               # mount partition
umount /dev/hda2                       # unmount partition
fuser -km /mnt/hda2                   # force unmount if busy
mount -o loop file.iso /mnt/iso        # mount ISO image
mount -t vfat /dev/hda5 /mnt/hda5      # mount FAT32 filesystem
mount -t cifs -o username=user,password=pass //WinClient/share /mnt/share  # mount Windows share

6. Disk Space and Filesystem Checks

df -h                                 # show mounted partitions with sizes
du -sh dir1                           # estimate disk usage of dir1
badblocks -v /dev/hda1               # check for bad blocks
fsck /dev/hda1                        # check and repair filesystem
e2fsck -j /dev/hda1                  # check ext3 filesystem
fsck.vfat /dev/hda1                   # check FAT filesystem

7. User and Group Management

groupadd group_name                  # create a new group
groupdel group_name                  # delete a group
groupmod -n new_name old_name        # rename a group
useradd -c "Name Surname" -g admin -d /home/user1 -s /bin/bash user1  # create user with details
userdel -r user1                    # delete user and home directory
usermod -c "User FTP" -g system -d /ftp/user1 -s /sbin/nologin user1   # modify user
passwd user1                         # change user password
chage -E 2005-12-31 user1            # set password expiration date

8. File Permissions

chmod ugo+rwx file1                  # give read/write/execute to everyone
chmod go-rwx file1                  # remove group and others permissions
chmod u+s file1                     # set SUID bit
chmod g+s directory1                # set SGID bit on directory
chmod o+t file1                     # set sticky bit

9. Special File Attributes (chattr)

chattr +a file1      # allow only append writes
chattr +i file1      # make immutable (cannot delete or modify)
chattr +c file1      # enable automatic compression
chattr -i file1      # remove immutable flag

10. Archiving and Compression

tar -cvf archive.tar file1               # create tar archive
tar -xvf archive.tar                     # extract tar archive
tar -cvzf backup.tar.gz /etc            # create gzip‑compressed archive
gzip file1                               # compress file
gunzip file1.gz                          # decompress file
bzip2 file1                              # compress with bzip2
bunzip2 file1.bz2                        # decompress bzip2 file
zip file1.zip file1                     # create zip archive
unzip file1.zip                          # extract zip archive

11. Package Management (RPM)

rpm -ivh package.rpm                     # install package
rpm -Uvh package.rpm                     # upgrade package
rpm -e package_name                      # remove package
rpm -qa                                 # list all installed RPMs
rpm -q package_name                      # query package information
rpm -ql package_name                     # list files provided by package

12. Package Management (YUM)

yum install package_name                 # install package and resolve dependencies
yum update package_name                 # update specific package
yum remove package_name                  # remove package
yum list all                            # list all packages
yum search keyword                      # search for packages
yum clean all                           # clean all cached data

13. Debian/Ubuntu Package Management (APT)

apt-get install package_name             # install package
apt-get update                           # update package list
apt-get upgrade                          # upgrade all packages
apt-get remove package_name              # remove package
apt-cache search keyword                 # search package cache

14. Network Commands

ifconfig eth0               # show Ethernet configuration
ifup eth0                    # enable interface
ifdown eth0                  # disable interface
dhclient eth0               # obtain IP via DHCP
route -n                    # display routing table
netstat -tup                # list active connections with PIDs
tcpdump -i eth0 port 80    # capture HTTP traffic
hostname                     # show system hostname
host www.example.com        # DNS lookup
nslookup www.example.com    # DNS lookup with details

15. System Monitoring

top                         # interactive process viewer
ps aux                      # snapshot of current processes
free -h                     # display memory usage
uptime                      # show system uptime
dmesg                       # kernel ring buffer messages

16. Text Processing

grep "pattern" file.txt               # search for pattern
sed 's/old/new/g' file.txt            # replace text
awk '{print $1}' file.txt             # process columns
sort file.txt                         # sort lines
uniq file.txt                         # filter duplicate lines
head -n 10 file.txt                   # first 10 lines
tail -f /var/log/messages             # follow log file

17. Miscellaneous Utilities

who                         # show logged‑in users
w                           # detailed user activity
chmod +x script.sh          # make script executable
chmod -x script.sh          # remove execute permission
file file1                  # determine file type
tar -cf - . | ssh user@host 'tar -xf - -C /dest'   # copy directory over SSH