1. Basic Commands
uname -m # Display the machine's processor architecture
uname -r # Display the currently used kernel version
dmidecode -q # Display hardware system components (SMBIOS / DMI)
hdparm -i /dev/hda # List a disk's architectural features
hdparm -tT /dev/sda # Perform a test read operation on the disk
arch # Display the machine's processor architecture
uname -m # Display the machine's processor architecture
uname -r # Display the currently used kernel version
dmidecode -q # Display hardware system components - (SMBIOS / DMI)
hdparm -i /dev/hda # List a disk's architectural features
hdparm -tT /dev/sda # Perform a test read operation on the disk
cat /proc/cpuinfo # Display CPU information
cat /proc/interrupts # Display interrupts
cat /proc/meminfo # Check memory usage
cat /proc/swaps # Show which swap is being used
cat /proc/version # Display kernel version
cat /proc/net/dev # Display network adapters and statistics
cat /proc/mounts # Display loaded file systems
lspci -tv # List PCI devices
lsusb -tv # Display USB devices
date # Display system date
cal 2007 # Display the calendar for the year 2007
date 041217002007.00 # Set date and time - month day hour minute year.second
clock -w # Save the time modification to BIOS2. Shutdown
shutdown -h now # Shut down the system (1)
init 0 # Shut down the system (2)
telinit 0 # Shut down the system (3)
shutdown -h hours:minutes & # Shut down the system at a scheduled time
shutdown -c # Cancel the scheduled shutdown
shutdown -r now # Reboot (1)
reboot # Reboot (2)
logout # Log out3. Files and Directories
cd /home # Enter the '/home' directory
cd .. # Return to the previous directory
cd ../.. # Return to the two levels up directory
cd # Enter the user's home directory
cd ~user1 # Enter the home directory of user1
cd - # Return to the last directory
pwd # Display the working path
ls # View files in the directory
ls -F # View files in the directory
ls -l # Display detailed information about files and directories
ls -a # Display hidden files
ls *[0-9]* # Display files and directories containing numbers
tree # Display the tree structure of files and directories starting from the root directory (1)
lstree # Display the tree structure of files and directories starting from the root directory (2)
mkdir dir1 # Create a directory named 'dir1'
mkdir dir1 dir2 # Create two directories simultaneously
mkdir -p /tmp/dir1/dir2 # Create a directory tree
rm -f file1 # Delete a file named 'file1'
rmdir dir1 # Delete a directory named 'dir1'
rm -rf dir1 # Delete a directory named 'dir1' and its contents
rm -rf dir1 dir2 # Delete two directories and their contents simultaneously
mv dir1 new_dir # Rename/move a directory
cp file1 file2 # Copy a file
cp dir/* . # Copy all files from a directory to the current working directory
cp -a /tmp/dir1 . # Copy a directory to the current working directory
cp -a dir1 dir2 # Copy a directory
ln -s file1 lnk1 # Create a symbolic link to a file or directory
ln file1 lnk1 # Create a hard link to a file or directory
touch -t 0712250000 file1 # Modify a file or directory's timestamp - (YYMMDDhhmm)
file file1 # Outputs the mime type of the file as text
iconv -l # List known encodings
iconv -f fromEncoding -t toEncoding inputFile > outputFile # Creates a new file from the given input file by assuming it is encoded in fromEncoding and converting it to toEncoding
find . -maxdepth 1 -name *.jpg -print -exec convert "{}" -resize 80x60 "thumbs/{}" \; # Batch resize files in the current directory and send them to a thumbnails directory (requires convert from Imagemagick4. File Search
find / -name file1 # Search for files and directories starting from '/' in the root file system
find / -user user1 # Search for files and directories owned by user 'user1'
find /home/user1 -name *.bin # Search for files ending with '.bin' in the directory '/home/user1'
find /usr/bin -type f -atime +100 # Search for executable files not used in the last 100 days
find /usr/bin -type f -mtime -10 # Search for files created or modified in the last 10 days
find / -name *.rpm -exec chmod 755 '{}' \; # Search for files ending with '.rpm' and set their permissions
find / -xdev -name *.rpm # Search for files ending with '.rpm', ignoring removable devices like CD-ROMs and USB drives
locate *.ps # Find files ending with '.ps' - first run 'updatedb' command
whereis halt # Show the location of a binary file, source, or man
which halt # Show the full path of a binary file or executable5. Mounting a File System
mount /dev/hda2 /mnt/hda2 # Mount a disk named hda2 - ensure the directory '/mnt/hda2' already exists
umount /dev/hda2 # Unmount a disk named hda2 - first exit from the mount point '/mnt/hda2'
fuser -km /mnt/hda2 # Force unmount when the device is busy
umount -n /mnt/hda2 # Run unmount operation without writing to /etc/mtab - useful when the file is read-only or when the disk is full
mount /dev/fd0 /mnt/floppy # Mount a floppy disk
mount /dev/cdrom /mnt/cdrom # Mount a CD-ROM or DVD-ROM
mount /dev/hdc /mnt/cdrecorder # Mount a CD-RW or DVD-ROM
mount /dev/hdb /mnt/cdrecorder # Mount a CD-RW or DVD-ROM
mount -o loop file.iso /mnt/cdrom # Mount a file or ISO image file
mount -t vfat /dev/hda5 /mnt/hda5 # Mount a Windows FAT32 file system
mount /dev/sda1 /mnt/usbdisk # Mount a USB flash drive or flash memory device
mount -t smbfs -o username=user,password=pass //WinClient/share /mnt/share # Mount a Windows network share6. Disk Space
df -h # Display a list of mounted partitions
ls -lSr | more # Sort files and directories by size
du -sh dir1 # Estimate the disk space used by directory 'dir1'
du -sk * | sort -rn # Display the size of files and directories in descending order
rpm -q -a --qf '%10{SIZE}t%{NAME}n' | sort -k1,1n # Display the space used by installed rpm packages sorted by size (Fedora, RedHat systems)
dpkg-query -W -f='${Installed-Size;10}t${Package}n' | sort -k1,1n # Display the space used by installed deb packages sorted by size (Ubuntu, Debian systems)7. Users and Groups
groupadd group_name # Create a new user group
groupdel group_name # Delete a user group
groupmod -n new_group_name old_group_name # Rename a user group
useradd -c "Name Surname" -g admin -d /home/user1 -s /bin/bash user1 # Create a user belonging to the "admin" user group
useradd user1 # Create a new user
userdel -r user1 # Delete a user ('-r' excludes the home directory)
usermod -c "User FTP" -g system -d /ftp/user1 -s /bin/nologin user1 # Modify user attributes
passwd # Change password
passwd user1 # Change a user's password (only allowed for root)
chage -E 2005-12-31 user1 # Set a user's password expiration date
pwck # Check the format and syntax of the '/etc/passwd' file and existing users
grpck # Check the format and syntax of the '/etc/group' file and existing groups
newgrp group_name # Log into a new group to change the default group for newly created files8. File Permissions, Use “+” to Set Permissions, Use “-” to Remove
chattr +a file1 # Allow file to be read and written only in append mode
chattr +c file1 # Allow this file to be automatically compressed/decompressed by the kernel
chattr +d file1 # Ignore this file during filesystem backups by the dump program
chattr +i file1 # Set as an immutable file, cannot be deleted, modified, renamed, or linked
chattr +s file1 # Allow a file to be securely deleted
chattr +S file1 # Once an application writes to this file, the system immediately writes the modified result to disk
chattr +u file1 # If the file is deleted, the system will allow you to recover the deleted file later
lsattr # Display special attributes9. Special File Attributes, Use “+” to Set Permissions, Use “-” to Remove
chattr +a file1 # Allow file to be read and written only in append mode
chattr +c file1 # Allow this file to be automatically compressed/decompressed by the kernel
chattr +d file1 # Ignore this file during filesystem backups by the dump program
chattr +i file1 # Set as an immutable file, cannot be deleted, modified, renamed, or linked
chattr +s file1 # Allow a file to be securely deleted
chattr +S file1 # Once an application writes to this file, the system immediately writes the modified result to disk
chattr +u file1 # If the file is deleted, the system will allow you to recover the deleted file later
lsattr # Display special attributes10. Packing and Compressing Files
bunzip2 file1.bz2 # Decompress a file named 'file1.bz2'
bzip2 file1 # Compress a file named 'file1'
gunzip file1.gz # Decompress a file named 'file1.gz'
gzip file1 # Compress a file named 'file1'
gzip -9 file1 # Maximum compression
rar a file1.rar test_file # Create a package named 'file1.rar'
rar a file1.rar file1 file2 dir1 # Compress 'file1', 'file2', and directory 'dir1' simultaneously
rar x file1.rar # Decompress rar package
unrar x file1.rar # Decompress rar package
tar -cvf archive.tar file1 # Create an uncompressed tarball
tar -cvf archive.tar file1 file2 dir1 # Create an archive file containing 'file1', 'file2', and 'dir1'
tar -tf archive.tar # Display the contents of a package
tar -xvf archive.tar # Extract a package
tar -xvf archive.tar -C /tmp # Extract the compressed package to /tmp directory
tar -cvfj archive.tar.bz2 dir1 # Create a bzip2 format compressed package
tar -xvfj archive.tar.bz2 # Decompress a bzip2 format compressed package
tar -cvfz archive.tar.gz dir1 # Create a gzip format compressed package
tar -xvfz archive.tar.gz # Decompress a gzip format compressed package
zip file1.zip file1 # Create a zip format compressed package
zip -r file1.zip file1 file2 dir1 # Compress several files and directories into a zip format compressed package
unzip file1.zip # Decompress a zip format compressed package11. RPM Packages
rpm -ivh package.rpm # Install an rpm package
rpm -ivh --nodeps package.rpm # Install an rpm package while ignoring dependency warnings
rpm -U package.rpm # Update an rpm package without changing its configuration files
rpm -F package.rpm # Update a specified installed rpm package
rpm -e package_name.rpm # Remove an rpm package
rpm -qa # Display all installed rpm packages in the system
rpm -qa | grep httpd # Display all rpm packages with "httpd" in their name
rpm -qi package_name # Get special information about an installed package
rpm -qg "System Environment/Daemons" # Display the rpm package of a component
rpm -ql package_name # Display the list of files provided by an installed rpm package
rpm -qc package_name # Display the list of configuration files provided by an installed rpm package
rpm -q package_name --whatrequires # Display a list of packages that have dependencies on an rpm package
rpm -q package_name --whatprovides # Display the size occupied by an rpm package
rpm -q package_name --scripts # Display scripts executed during installation/removal
rpm -qf /etc/httpd/conf/httpd.conf # Confirm which rpm package provides the given file
rpm -qp package.rpm -l # Display the list of files provided by an uninstalled rpm package
rpm --import /media/cdrom/RPM-GPG-KEY # Import public key certificate
rpm --checksig package.rpm # Confirm the integrity of an rpm package
rpm -qa gpg-pubkey # Confirm the integrity of all installed rpm packages
rpm -V package_name # Check file size, permissions, type, owner, group, MD5 checksum, and last modification time
rpm -Va # Check all installed rpm packages in the system - use with caution
rpm -Vp package.rpm # Confirm an rpm package that has not been installed
rpm2cpio package.rpm | cpio --extract --make-directories # Extract executable files from an rpm package
rpm -ivh /usr/src/redhat/RPMS/`arch`/package.rpm # Install a built package from an rpm source
rpmbuild --rebuild package_name.src.rpm # Build an rpm package from an rpm source12. YUM Package Updater
yum install package_name # Download and install an rpm package
yum localinstall package_name.rpm # Install an rpm package, using your own software repository to resolve all dependencies
yum update package_name.rpm # Update all installed rpm packages in the current system
yum update package_name # Update an rpm package
yum remove package_name # Remove an rpm package
yum list # List all packages installed in the current system
yum search package_name # Search for software packages in the rpm repository
yum clean packages # Clean rpm cache and remove downloaded packages
yum clean headers # Remove all header files
yum clean all # Remove all cached packages and header files13. deb Packages
dpkg -i package.deb # Install/update a deb package
dpkg -r package_name # Remove a deb package
dpkg -l # Display all installed deb packages in the system
dpkg -l | grep httpd # Display all deb packages with "httpd" in their name
dpkg -s package_name # Get information about a specific package installed in the system
dpkg -L package_name # Display the list of files provided by an installed deb package
dpkg --contents package.deb # Display the list of files provided by an uninstalled package
dpkg -S /bin/ping # Confirm which deb package provides the given file
APT Software Tools (Debian, Ubuntu, and similar systems)
apt-get install package_name # Install/update a deb package
apt-cdrom install package_name # Install/update a deb package from a CD
apt-get update # Upgrade the list of software packages
apt-get upgrade # Upgrade all installed software
apt-get remove package_name # Remove a deb package
apt-get check # Confirm that the dependency software repository is correct
apt-get clean # Clean the cache from downloaded software packages
apt-cache search searched-package # Return the names of software packages containing the search string14. View File Contents
cat file1 # View the contents of a file from the first byte
tac file1 # View a file's contents in reverse from the last line
more file1 # View the contents of a long file
less file1 # Similar to 'more' command, but allows reverse operations in the file
head -2 file1 # View the first two lines of a file
tail -2 file1 # View the last two lines of a file
tail -f /var/log/messages # Real-time view of content added to a file15. Text Processing
cat file1 file2 ... | command <> file1_in.txt_or_file1_out.txt # General syntax for text manipulation using PIPE, STDIN and STDOUT
cat file1 | command( sed, grep, awk, grep, etc...) > result.txt # Merge detailed text from a file and write the summary to a new file
cat file1 | command( sed, grep, awk, grep, etc...) >> result.txt # Merge detailed text from a file and write the summary to an existing file
grep Aug /var/log/messages # Search for the keyword "Aug" in the file '/var/log/messages'
grep ^Aug /var/log/messages # Search for words starting with "Aug" in the file '/var/log/messages'
grep [0-9] /var/log/messages # Select all lines in the '/var/log/messages' file containing numbers
grep Aug -R /var/log/* # Search for the string "Aug" in the '/var/log' directory and subsequent directories
sed 's/stringa1/stringa2/g' example.txt # Replace "string1" with "string2" in example.txt
sed '/^$/d' example.txt # Delete all blank lines from example.txt
sed '/ *#/d; /^$/d' example.txt # Delete all comments and blank lines from example.txt
echo 'esempio' | tr '[:lower:]' '[:upper:]' # Merge upper and lower cell contents
sed -e '1d' result.txt # Exclude the first line from example.txt
sed -n '/stringa1/p' # View only lines containing the word "string1"
sed -e 's/ *$//' example.txt # Delete trailing whitespace from each line
sed -e 's/stringa1//g' example.txt # Remove the word "string1" from the document while keeping the rest
sed -n '1,5p;5q' example.txt # View content from the first to the fifth line
sed -n '5p;5q' example.txt # View the fifth line
sed -e 's/00*/0/g' example.txt # Replace multiple zeros with a single zero
cat -n file1 # Number the lines of the file
cat example.txt | awk 'NR%2==1' # Delete all even lines from example.txt
echo a b c | awk '{print $1}' # View the first column of a line
echo a b c | awk '{print $1,$3}' # View the first and third columns of a line
paste file1 file2 # Merge the contents of two files or columns
paste -d '+' file1 file2 # Merge the contents of two files or columns, separated by "+"
sort file1 file2 # Sort the contents of two files
sort file1 file2 | uniq # Get the union of two files (duplicate lines are kept only once)
sort file1 file2 | uniq -u # Delete the intersection, leaving other lines
sort file1 file2 | uniq -d # Get the intersection of two files (only keep files that exist in both files)
comm -1 file1 file2 # Compare the contents of two files, only delete content contained in 'file1'
comm -2 file1 file2 # Compare the contents of two files, only delete content contained in 'file2'
comm -3 file1 file2 # Compare the contents of two files, only delete the common parts of both files16. Character Settings and File Format Conversion
dos2unix filedos.txt fileunix.txt # Convert a text file format from MSDOS to UNIX
unix2dos fileunix.txt filedos.txt # Convert a text file format from UNIX to MSDOS
recode ..HTML < page.txt > page.html # Convert a text file to html
recode -l | more # Display all allowed conversion formats17. File System Analysis
badblocks -v /dev/hda1 # Check for bad blocks on disk hda1
fsck /dev/hda1 # Repair/check the integrity of the Linux file system on disk hda1
fsck.ext2 /dev/hda1 # Repair/check the integrity of the ext2 file system on disk hda1
e2fsck /dev/hda1 # Repair/check the integrity of the ext2 file system on disk hda1
e2fsck -j /dev/hda1 # Repair/check the integrity of the ext3 file system on disk hda1
fsck.ext3 /dev/hda1 # Repair/check the integrity of the ext3 file system on disk hda1
fsck.vfat /dev/hda1 # Repair/check the integrity of the fat file system on disk hda1
fsck.msdos /dev/hda1 # Repair/check the integrity of the dos file system on disk hda1
dosfsck /dev/hda1 # Repair/check the integrity of the dos file system on disk hda118. Initializing a File System
mkfs /dev/hda1 # Create a file system on partition hda1
mke2fs /dev/hda1 # Create a Linux ext2 file system on partition hda1
mke2fs -j /dev/hda1 # Create a Linux ext3 (journaled) file system on partition hda1
mkfs -t vfat 32 -F /dev/hda1 # Create a FAT32 file system
fdformat -n /dev/fd0 # Format a floppy disk
mkswap /dev/hda3 # Create a swap file system19. SWAP File System
mkswap /dev/hda3 # Create a swap file system
swapon /dev/hda3 # Enable a new swap file system
swapon /dev/hda2 /dev/hdb3 # Enable two swap partitions20. Backup
dump -0aj -f /tmp/home0.bak /home # Create a full backup of the '/home' directory
dump -1aj -f /tmp/home0.bak /home # Create an interactive backup of the '/home' directory
restore -if /tmp/home0.bak # Restore an interactive backup
rsync -rogpav --delete /home /tmp # Synchronize directories on both sides
rsync -rogpav -e ssh --delete /home ip_address:/tmp # Synchronize a remote directory via SSH
rsync -az -e ssh --delete ip_addr:/home/public /home/local # Synchronize a remote directory to a local directory via ssh and compression
rsync -az -e ssh --delete /home/local ip_addr:/home/public # Synchronize a local directory to a remote directory via ssh and compression
dd bs=1M if=/dev/hda | gzip | ssh user@ip_addr 'dd of=hda.gz' # Perform a backup of the local disk on a remote host via ssh
dd if=/dev/sda of=/tmp/file1 # Backup disk content to a file
tar -Puf backup.tar /home/user # Perform an interactive backup operation on the '/home/user' directory
( cd /tmp/local/ && tar c . ) | ssh -C user@ip_addr 'cd /home/share/ && tar x -p' # Copy a directory's content to a remote directory via ssh
( tar c /home ) | ssh -C user@ip_addr 'cd /home/backup-home && tar x -p' # Copy a local directory's content to a remote directory via ssh
tar cf - . | (cd /tmp/backup ; tar xf - ) # Locally copy a directory to another place, preserving original permissions and links
find /home/user1 -name '*.txt' | xargs cp -av --target-directory=/home/backup/ --parents # Find and copy all files ending with '.txt' to another directory
find /var/log -name '*.log' | tar cv --files-from=- | bzip2 > log.tar.bz2 # Find all files ending with '.log' and create a bzip package
dd if=/dev/hda of=/dev/fd0 bs=512 count=1 # Copy the MBR (Master Boot Record) content to a floppy disk
dd if=/dev/fd0 of=/dev/hda bs=512 count=1 # Restore MBR content from a saved floppy backup21. CD-ROM
cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force # Clear the contents of a rewritable CD
mkisofs /dev/cdrom > cd.iso # Create an ISO image file of a CD on disk
mkisofs /dev/cdrom | gzip > cd_iso.gz # Create a compressed ISO image file of a CD on disk
mkisofs -J -allow-leading-dots -R -V "Label CD" -iso-level 4 -o ./cd.iso data_cd # Create an ISO image file of a directory
cdrecord -v dev=/dev/cdrom cd.iso # Burn an ISO image file
gzip -dc cd_iso.gz | cdrecord dev=/dev/cdrom - # Burn a compressed ISO image file
mount -o loop cd.iso /mnt/iso # Mount an ISO image file
cd-paranoia -B # Transcribe audio tracks from a CD to wav files
cd-paranoia -- "-3" # Transcribe audio tracks from a CD to wav files (parameter -3)
cdrecord --scanbus # Scan the bus to identify SCSI channels
dd if=/dev/hdc | md5sum # Check the md5sum encoding of a device, such as a CD22. Networking (Ethernet and WIFI)
ifconfig eth0 # Display the configuration of an Ethernet card
ifup eth0 # Enable an 'eth0' network device
ifdown eth0 # Disable an 'eth0' network device
ifconfig eth0 192.168.1.1 netmask 255.255.255.0 # Control IP address
ifconfig eth0 promisc # Set 'eth0' to promiscuous mode to sniff packets (sniffing)
dhclient eth0 # Enable 'eth0' in DHCP mode
route -n # Show routing table
route add -net 0/0 gw IP_Gateway # Configure default gateway
route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1 # Configure static route to reach network '192.168.0.0/16'
route del 0/0 gw IP_gateway # Remove static route
echo "1" > /proc/sys/net/ipv4/ip_forward # Activate IP routing
hostname # Show the hostname of the system
host www.example.com # Lookup hostname to resolve name to IP address and vice versa (1)
snlookup www.example.com # Lookup hostname to resolve name to IP address and vice versa (2)
ip link show # Show link status of all interfaces
mii-tool eth0 # Show link status of 'eth0'
ethtool eth0 # Show statistics of network card 'eth0'
netstat -tup # Show all active network connections and their PID
netstat -tupl # Show all network services listening on the system and their PID
tcpdump tcp port 80 # Show all HTTP traffic
iwlist scan # Show wireless networks
iwconfig eth1 # Show configuration of a wireless network card
hostname # Show hostname
host www.example.com # Lookup hostname to resolve name to IP address and vice versa
nslookup www.example.com # Lookup hostname to resolve name to IP address and vice versa
whois www.example.com # Lookup on Whois database23. Listing Directory Contents
ls -a: # Display all files (including hidden files);
ls -l: # Display detailed information;
ls -R: # Recursively display subdirectory structure;
ls -ld: # Display directory and link information;
ctrl+r: # Search command in history (input any character in the command);
# Files starting with . in Linux are hidden files;
pwd: # Display current directory24. View File Type
file: # View file type25. Copy Files and Directories
1. cp: # Copy files and directories
cp source_file (folder) target_file (folder). Common parameters: -r: # Recursively copy the entire directory tree;
-v: # Display detailed information;
# When copying folders, add the -r parameter after the cp command:
# Example: cp -r source_folder target_folder.2. touch + filename: # Create the corresponding file when it does not exist; modify the creation time of the file when it exists.
# Function: Generate an empty file or modify the access/modification time record value of the file;
touch * : # Modify the file time to the current system time;
touch -d 20040210 test: # Change the date of the test file to 20040210;
touch abc: # If the abc file exists, modify it to the current system time; if it does not exist, generate an empty file with the current time.3. mv file target_directory: # Move or rename files or directories (if a file name is specified, it can rename the file).
# You can move files and directories to another directory or change the names of files and directories.
# Format: mv [parameters] <source directory="" file="" or=""/> <target directory="" file="" or="">
mv a.txt ../: # Move a.txt file to the upper directory
mv a.txt b.txt: # Rename a.txt to b.txt
mv dir2 ../: # Move dir2 directory up one level</target>4. rm: # Delete files
Common parameters: -i: # Interactive -r: # Recursively delete all contents including directories.5. mkdir + folder name: # Create a folder6. rm -r + folder name: # Delete a folder (both empty and non-empty folders can be deleted);
rmdir folder name: # Delete a folder (can only delete empty folders).7. mkdir -p dir1/dir2: # Create dir1 directory under the current directory, and create dir2 directory under dir1 directory, i.e., create two directories consecutively (dir1/ and dir1/dir2).8. rmdir -p dir1/dir2: # Delete dir2 directory under dir1, if dir1 is empty, delete it as well.9. rm * : # Delete all files in the current directory10. -f parameter: # Force delete files
rm -f *.txt: # Force delete all files with the suffix .txt.11. -i parameter: # Ask when deleting files
rm -i * : # Deleting all files in the current directory will prompt:
# rm: backup: is a directory
# When encountering a directory, it will be skipped
# rm: remove ‘myfiles.txt’ ? Y # When deleting files, it will ask, you can press Y or N to allow or refuse to delete files.12. -r parameter: # Recursively delete (delete subdirectories as well, this is a very common parameter).
rm -r test : # Delete the test directory (including all files and subdirectories under the test directory);
rm -r *: # Delete all files (including all files in the current directory, all subdirectories, and files under subdirectories)
# Generally, when deleting directories, use r and f together to avoid trouble;
rm -rf test : # Force delete without asking.13. grep: # Function: Search for matching characters in a file and output.
# Format: grep [parameters] <string find="" to=""> <source file="" search="" to=""/>
grep linux test.txt: # Search for the string linux in the test.txt file and output.</string>14. ln command function: # Establish links between files and directories
# Format: ln [parameters] <source directory="" file="" or=""/> <target directory="" file="" or="">
# Links are divided into "soft links" and "hard links"
1. Soft link: ln -s /usr/share/do doc : # Create a link file doc, pointing to directory /usr/share/do
2. Hard link: ln /usr/share/test hard: # Create a hard link file hard, at this time, for the test file corresponding storage area, there is another file pointing to it.</target>26. Common System Commands
1. Display Commands
date: # View or set the current system time:
# Format the display time: +%Y--%m--%d;
date -s: # Set the current system time;
hwclock(clock): # Display hardware clock time (requires administrator privileges);
cal: # View calendar;
# Format cal [parameters] month year;
cal: # Display the current month's calendar
cal 4 2004 : # Display the calendar for April 2004;
cal -y 2003: # Display the calendar for the year 2003;
uptime: # View system uptime2. Output Viewing Commands
echo: # Display input content Append to file
echo "liuyazhuang" >> liuyazhuang.txt
cat: # Display file contents, can also merge several files into one file;
# Format: cat [parameters] <filename>
cat test.txt: # Display the contents of test.txt file;
cat test.txt | more : # Display the contents of test.txt file page by page;
cat test.txt >> test1.txt : # Append the contents of test.txt to test1.txt;
cat test.txt test2.txt > readme.txt : # Merge test.txt and test2.txt files into readme.txt file;
head: # Display the first few lines of a file (default 10 lines) -n: # Specify the number of lines to display; format: head -n filename;
tail: # Display the last few lines of a file (default 10 lines) -n: # Specify the number of lines to display -f: # Track and display file updates (generally used to view logs, the command will not exit, but will continuously display new content added);
# Format: tail [parameters] <filename>
tail -10 /etc/passwd : # Display the last 10 lines of the /etc/passwd file;
tail +10 /etc/passwd : # Display the contents of the /etc/passwd file from the 10th line to the end;
more: # Used to display file contents page by page (can only scroll down);
# The more command is generally used when the content to be displayed exceeds one screen length. To avoid the content flashing by instantly, users can use the more command, allowing the screen to pause when it is full. You can press the space bar to continue displaying the next screen, or press Q to stop displaying;
ls -al | more: # Display the file list in the etc directory in long format, pausing when the screen is full, you can press the space bar to continue displaying the next screen, or press Q to exit;
less: # Page display file contents (with up and down scrolling) press the up key to page, press q to exit;
# The less command is similar to the more command, but also allows scrolling up and down. When you want to end browsing, just press Q at the prompt of the less command.</filename></filename>3. View Hardware Information
lspci: # View PCI devices -v: # View detailed information
lsusb: # View USB devices -v: # View detailed information
lsmod: # View loaded modules (drivers)4. Shutdown, Reboot
shutdown # Shut down, reboot the computer
shutdown [shutdown, reboot] time -h # Shut down the computer -r: # Reboot the computer
# Example: Shut down immediately: shutdown -h now
# Shut down after 10 minutes: shutdown -h +10
# Shut down at 23:30: shutdown -h 23:30
# Reboot immediately: shutdown -r now
poweroff: # Shut down the computer immediately
reboot: # Reboot the computer immediately5. Archiving, Compressing
zip: # Compress files zip liuyazhuang.zip myfile # Format: "zip compressed zip file name"
unzip: # Decompress files unzip liuyazhuang.zip
gzip: # Compress files gzip filename
tar: # Archive files
tar -cvf out.tar liuyazhuang # Pack an archive (pack the file "liuyazhuang" into an archive)
tar -xvf liuyazhuang.tar # Extract an archive (extract liuyazhuang.tar archive)
tar -cvzf backup.tar.gz /etc -z parameter will compress the archived file using gzip to reduce size.
-c: # Create a new tar file
-v: # Display the running process information
-f: # Specify file name
-z: # Call gzip compression command for compression
-t: # View the contents of the compressed file
-x: # Unpack the tar file
tar -cvf test.tar *: # Pack all files into test.tar, the extension .tar must be added manually
tar -zcvf test.tar.gz *: # Pack all files into test.tar, then compress with gzip command
tar -tf test.tar : # View which files are included in the test.tar file
tar -xvf test.tar # Unpack test.tar
tar -zxvf foo.tar.gz # Decompress gzip
# Each gzip command does not require any parameters
gzip test.txt : # Compress files
# gzip -l test.txt.gz: # Display compression rate6. Search
locate: # Quickly find files, folders: locate keyword
# This command requires a pre-established database, the database is updated once a day by default, you can use the updatedb command to manually establish or update the database.
find: # Find location
# Search parameters:
find . -name *liuyazhuang* # Find files containing "liuyazhuang" in the current directory
find / -name *.conf # Find files with the suffix .conf in the root directory (entire hard drive)
find / -perm 777 # Find all files with permission 777
find / -type d # Return all directories in the root directory
find . -name "a*" -exec ls -l {} \; # Find function: used to find files or directories
# Format: find [<path>] [matching conditions]
find / -name httpd.conf # Search for the file named httpd.conf in the system root directory</path>7. ctrl+c : Terminate the current command
8. who or w command
who or w command function: # View which users are logged into the current system
# Format: who/w [parameters]9. dmesg command
dmesg command function: # Display system diagnostic information, operating system version number, physical memory size, and other information.10. df command
df command function: # Used to view the usage of each partition of the file system.11. du command
du command function: # View the disk space used by each level of subdirectories in a directory. Format: du [parameters] <directory name=""></directory>12. free command
free command function: # Used to view the size and usage of system memory and virtual memory (swap space).27. VIM
VIM is a powerful command-line text editor, which can be started in Linux using the vim command.
Generally, use vim + target file path to use vim
If the target file exists, vim opens the target file; if the target file does not exist, vim creates and opens that file.
:q: # Exit vim editor
VIM Modes
vim has three modes:
(1) Command Mode (Normal Mode)
After vim starts, it enters command mode by default, any mode can return to command mode by pressing the esc key (you can press it multiple times), in command mode you can type different commands to complete selection, copy, paste, undo, etc.
Common commands in command mode are as follows:
i : # Insert text before the cursor
o: # Insert a new line below the current line
dd: # Delete the entire line
yy: # Put the content of the current line into the buffer (copy the current line)
n+yy : # Put the content of n lines into the buffer (copy n lines)
p: # Paste the text from the buffer after the cursor
u: # Undo the last operation
r: # Replace the current character
/ # Search for keywords(2) Insert Mode
Press the ” i ” key in command mode to enter insert mode, in insert mode you can input and edit text content, use the esc key to return to command mode.
(3) ex Mode
Press the “:” key in command mode to enter ex mode, the cursor will move to the bottom, where you can save changes or exit vim.
Common commands in ex mode are as follows:
:w # Save the current changes
:q # Exit
:q! # Force exit, save changes
:x # Save and exit, equivalent to :wq
:set number # Display line numbers
:! # System command # Execute a system command and display the result
:sh # Switch to command line, use ctrl+d to switch back to vim28. Software Package Management Commands (RPM)
1. Software Package Installation
1. Software Package Installation
Using the RPM command's installation mode, you can place all components of the software package in the correct path in the system, the command to install the software package is:
rpm –ivh wu-ftpd-2.6.2-8.i386.rpm
# i: # Effect of rpm's installation mode
# v: # Verify file information
# h: # Display installation progress with #2. Software Package Deletion
2. Software Package Deletion
The deletion mode will remove all contents of the specified software package, but does not include modified configuration files, the command to delete an RPM software package is:
rpm –e wu-ftpd
# Note: Here you must use the software name "wu-ftpd" or "wu-ftpd-2.6.2-8" instead of using the package name used during installation "wu-ftpd-2.6.2-8.i386.rpm"3. Software Package Upgrade
3. Software Package Upgrade
The upgrade mode will install the updated version specified by the user and remove the same software package already installed in the system, the command to upgrade the software package is:
rpm –Uvh wu-ftpd-2.6.2-8.i386.rpm –Uvh: # Upgrade parameter.4. Software Package Update
4. Software Package Update
In update mode, the rpm command will check whether the specified software package in the command line is newer than the original software package in the system. If so, the rpm command will automatically update the specified software package; otherwise, if there is no older version of the specified software package in the system, the rpm command will not install this package. In upgrade mode, regardless of whether there is an older version in the system, the rpm command will install the specified software package.
rpm –Fvh wu-ftpd-2.6.2-8.i386.rpm -Fvh: # Update parameter5. Software Package Query
5. Software Package Query
If you want to get information about the RPM software package, you can use the query mode. Use the -q parameter to query the content of an installed software package.
rpm –q wu-ftpd # Query the installed location of the software package:
rpm –ql package-name
rpm –ql xv (l parameter: # Display file list)29. Finally:
Due to my own level, there are errors in it, I hope everyone can give guidance, Han Xin points soldiers – the more the better, thank you all, see you again in the rivers and lakes!!!
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