(Transfer) A complete collection of common Linux commands (very complete!!!)

system message

• arch Displays the processor architecture of the machine
• uname -m shows the processor architecture of the machine
• uname -r shows the kernel version in use
• dmidecode -q show hardware system components - (SMBIOS/DMI)
• hdparm -i /dev/hda lists the architectural properties of a disk
• hdparm -tT /dev/sda performs a test read on the disk
• cat /proc/cpuinfo display CPU info information
• cat /proc/interrupts shows interrupts
• cat /proc/meminfo check memory usage
• cat /proc/swaps shows which swaps are used
• cat /proc/version shows the version of the kernel
• cat /proc/net/dev displays network adapters and statistics
• cat /proc/mounts shows mounted filesystems
• lspci -tv list PCI devices
• lsusb -tv show usb devices
• date display system date
• cal 2007 displays the calendar for 2007
• date 041217002007.00 Set date and time - month day hour minute year.second
• clock -w save time modification to BIOS

Shutdown (shutdown, restart and logout of the system)

• shutdown -h now shut down the system
• init 0 shut down the system
• telinit 0 shut down the system
• shutdown -h hours:minutes & Shut down the system according to the scheduled time
• shutdown -c cancels shutting down the system at a scheduled time
• shutdown -r now restart
• reboot reboot
• logout

files and directories

• cd /home into the '/home' directory'
• cd ... Return to the previous directory
• cd …/… Return to the previous two directories
• cd into your home directory
• cd ~user1 enters the personal home directory
• cd - return to last directory
• pwd show working path
• ls View files in a directory
• ls -F View files in a directory
• ls -l displays detailed information about files and directories
• ls -a show hidden files
• ls [0-9] displays filenames and directory names containing numbers
• tree Displays the tree structure of files and directories starting from the root directory
• lstree displays the tree structure of files and directories starting from the root directory
• mkdir dir1 creates a directory called 'dir1'
• mkdir dir1 dir2 creates two directories at the same time
• mkdir -p /tmp/dir1/dir2 creates a directory tree
• rm -f file1 Delete a file called 'file1''
• rmdir dir1 removes a directory called 'dir1'
• rm -rf dir1 Delete a directory called 'dir1' and delete its contents
• rm -rf dir1 dir2 delete both directories and their contents
• mv dir1 new_dir rename/move a directory
• cp file1 file2 copies a file
• cp dir/* . Copy all files in 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 creates a soft link pointing to a file or directory
• ln file1 lnk1 creates a physical link to a file or directory
• touch -t 0712250000 file1 Modify the timestamp of a file or directory - (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 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 Imagemagick)

file search

• find / -name file1 starts from '/' to enter the root file system to search for files and directories
• find / -user user1 searches for files and directories belonging to user 'user1'
• find /home/user1 -name *.bin searches for files ending with '.bin' in directory '/home/user1'
• find /usr/bin -type f -atime +100 Search for executable files that have not been used in the past 100 days
• find /usr/bin -type f -mtime -10 Search for files created or modified within 10 days
• find / -name *.rpm -exec chmod 755 '{}' ; search for files ending with '.rpm' and define their permissions
• find / -xdev -name *.rpm Search for files ending with '.rpm', ignoring removable devices such as CD-ROMs and shortcuts
• locate *.ps finds files ending in '.ps' - run 'updatedb' first
• whereis halt shows the location of a binary, source or man
• which halt displays the full path to a binary or executable

mount a filesystem

• mount /dev/hda2 /mnt/hda2 mounts a disk called hda2 - make sure the directory '/mnt/hda2' already exists
• umount /dev/hda2 Unmount a disk called hda2 - first exit from the mount point '/mnt/hda2'
• fuser -km /mnt/hda2 Force unmount when device is busy
• umount -n /mnt/hda2 runs the unmount without writing the /etc/mtab file - 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 cdrom or dvdrom
• mount /dev/hdc /mnt/cdrecorder mount a cdrw or dvdrom
• mount /dev/hdb /mnt/cdrecorder mount a cdrw or dvdrom
• 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 shortcut or flash device
• mount -t smbfs -o username=user,password=pass //WinClient/share /mnt/share mount a windows network share

disk space

• df -h displays a list of mounted partitions
• ls -lSr |more Arrange files and directories by size
• du -sh dir1 Estimate the disk space used by the directory 'dir1'
• du -sk * | sort -rn Display the size of files and directories in order based on the size of the capacity
• rpm -q -a --qf '%10{SIZE}t%{NAME}n' | sort -k1,1n Display the space used by the installed rpm packages in turn based on size (fedora, redhat-like systems)
• dpkg-query -W -f=’$Installed-Size;10t$ {Package}n' | sort -k1,1n show space used by installed deb packages by size (ubuntu, debian-like systems)

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 creates a new user
• userdel -r user1 delete a user ('-r' exclude home directory)
• usermod -c "User FTP" -g system -d /ftp/user1 -s /bin/nologin user1 Modify user attributes
• passwd Change password
• passwd user1 Modify a user's password (only root execution is allowed)
• chage -E 2005-12-31 user1 Set the expiration date of the user password
• pwck checks '/etc/passwd' for file format and syntax corrections and existing users
• grpck checks '/etc/passwd' for file format and syntax corrections and existing groups
• newgrp group_name Login into a new group to change the default group for newly created files

File Permissions - Use '+' to set permissions, '-' to cancel

• ls -lh show permissions
• ls /tmp | pr -T5 -W$COLUMNS Divide the terminal into 5 columns for display
• chmod ugo+rwx directory1 Set the directory owner (u), group (g) and others (o) to read (r), write (w) and execute (x) permissions
• chmod go-rwx directory1 delete group (g) and others (o) read, write and execute permissions on the directory
• chown user1 file1 Change the owner attribute of a file
• chown -R user1 directory1 Change the owner attribute of a directory and change the attributes of all files in the directory at the same time
• chgrp group1 file1 change the group of the file
• chown user1:group1 file1 Change the owner and group attributes of a file
• find / -perm -u+s lists all files in a system that use SUID control
• chmod u+s /bin/file1 sets the SUID bit of a binary file - the user running the file is also given the same permissions as the owner
• chmod us /bin/file1 disable SUID bit for a binary file
• chmod g+s /home/public Set a directory's SGID bit - like SUID, but for directories
• chmod gs /home/public disables the SGID bit for a directory
• chmod o+t /home/public Set a file's STIKY bit - allow only legal owners to delete files
• chmod ot /home/public disables the STIKY bit for a directory

File special attributes - use '+' to set permissions, '-' to cancel

• chattr +a file1 only allows reading and writing files in append mode
• chattr +c file1 allows this file to be automatically compressed/decompressed by the kernel
• chattr +d file1 When doing a file system backup, the dump program will ignore this file
• chattr +i file1 set to an immutable file that cannot be deleted, modified, renamed or linked
• chattr +s file1 allows a file to be safely deleted
• chattr +S file1 Once the application program writes to this file, the system immediately writes the modified result to the disk
• chattr +u file1 If the file is deleted, the system will allow you to restore the deleted file later
• lsattr displays special attributes

Pack and compress files

• bunzip2 file1.bz2 unzip a file called 'file1.bz2'
• bzip2 file1 compresses a file called 'file1'
• gunzip file1.gz decompresses a file called 'file1.gz'
• gzip file1 Compress a file called 'file1'
• gzip -9 file1 maximum compression
• rar a file1.rar test_file creates a package called 'file1.rar'
• rar a file1.rar file1 file2 dir1 compress 'file1', 'file2' and directory 'dir1' at the same time
• unrar x file1.rar decompress rar package
• tar -cvf archive.tar file1 creates an uncompressed tarball
• tar -cvf archive.tar file1 file2 dir1 Create an archive containing 'file1', 'file2' and 'dir1'
• tar -tf archive.tar displays the contents of a package
• tar -xvf archive.tar releases a package
• tar -xvf archive.tar -C /tmp release the compressed package to the /tmp directory
• tar -cvfj archive.tar.bz2 dir1 Create a compressed package in bzip2 format
• tar -jxvf archive.tar.bz2 decompress a compressed package in bzip2 format
• tar -cvfz archive.tar.gz dir1 Create a compressed package in gzip format
• tar -zxvf archive.tar.gz decompresses a compressed package in gzip format
• zip file1.zip file1 creates a compressed package in zip format
• zip -r file1.zip file1 file2 dir1 Compress several files and directories into a compressed package in zip format at the same time
• unzip file1.zip Unzip a compressed package in zip format

RPM package - (Fedora, Redhat and similar systems)

• rpm -ivh package.rpm install an rpm package
• rpm -ivh --nodeeps package.rpm install an rpm package and ignore dependency warnings
• rpm -U package.rpm updates an rpm package without changing its configuration file
• rpm -F package.rpm update a confirmed installed rpm package
• rpm -e package_name.rpm delete a rpm package
• rpm -qa displays all installed rpm packages in the system
• rpm -qa | grep httpd displays all rpm packages with "httpd" in their name
• rpm -qi package_name Get specific information about an installed package
• rpm -qg "System Environment/Daemons" displays the rpm package of a component
• rpm -ql package_name displays a list of files provided by an installed rpm package
• rpm -qc package_name displays a list of configuration files provided by an installed rpm package
• rpm -q package_name --whatrequires displays a list of dependencies with an rpm package
• rpm -q package_name --whatprovides shows the volume occupied by an rpm package
• rpm -q package_name --scripts show scripts executed during installation/removal
• rpm -q package_name --changelog displays the modification history of an rpm package
• rpm -qf /etc/httpd/conf/httpd.conf Confirm which rpm package provides the given file
• rpm -qp package.rpm -l displays a list of files provided by an rpm package that has not been installed
• rpm --import /media/cdrom/RPM-GPG-KEY import public key digital 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, permission, type, owner, group, MD5 check and last modification time
• rpm -Va checks all installed rpm packages on the system - use with care
• rpm -Vp package.rpm Confirm that an rpm package is not installed
• rpm2cpio package.rpm | cpio --extract --make-directories bin Run executables from an rpm package
• rpm -ivh /usr/src/redhat/RPMS/ arch/package.rpm installs a built package from an rpm source
• rpmbuild --rebuild package_name.src.rpm build an rpm package from an rpm source

YUM Package Upgrader - (Fedora, RedHat and similar)

• yum install package_name download and install an rpm package
• yum localinstall package_name.rpm will install an rpm package, using your own software repository to resolve all dependencies for you
• yum update package_name.rpm updates all installed rpm packages in the current system
• yum update package_name updates an rpm package
• Yum remove package_name deletes an rpm package
• yum list lists all packages installed in the current system
• yum search package_name searches for packages in the rpm repository
• yum clean packages to clean up rpm cache and delete downloaded packages
• yum clean headers delete all header files
• yum clean all removes all cached packages and header files

DEB package (Debian, Ubuntu and similar)

• dpkg -i package.deb install/update a deb package
• dpkg -r package_name removes a deb package from the system
• dpkg -l displays all deb packages installed in the system
• dpkg -l | grep httpd displays all deb packages with "httpd" in their name
• dpkg -s package_name Get information about a particular package already installed on the system
• dpkg -L package_name displays a list of files provided by a deb package already installed in the system
• dpkg --contents package.deb display a list of files provided by a package that is not yet installed
• 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 installs/updates a deb package
• apt-cdrom install package_name install/update a deb package from CD
• apt-get update upgrades packages in the list
• apt-get upgrade upgrades all installed software
• apt-get remove package_name removes a deb package from the system
• apt-get check confirms that the dependent software warehouse is correct
• apt-get clean cleans the cache from downloaded packages
• apt-cache search searched-package returns the package name containing the searched string

view file content

• cat file1 looks forward through the contents of the file starting from the first byte
• tac file1 view the contents of a file in reverse, starting from the last line
• more file1 view the contents of a long file
• less file1 similar to the 'more' command, but it allows reverse operations on files as well as forward operations
• 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 View what is added to a file in real time

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 Combine the detailed text of a file and write the introduction into a new file
• cat file1 | command( sed, grep, awk, grep, etc…) >> result.txt Combine the detailed text of a file and write the introduction into an existing file
• grep Aug /var/log/messages looks for the keyword "Aug" in the file '/var/log/messages'
• grep ^Aug /var/log/messages Find words starting with "Aug" in the file '/var/log/messages'
• grep [0-9] /var/log/messages selects all lines containing numbers in the '/var/log/messages' file
• grep Aug -R /var/log/* Search for the string "Aug" in the directory '/var/log' and subsequent directories
• sed 's/stringa1/stringa2/g' example.txt Replace "string1" in the example.txt file with "string2"
• sed '/^$/d' example.txt removes all blank lines from the example.txt file
• sed '/ *#/d; /^$/d' example.txt removes all comments and blank lines from the example.txt file
• echo 'esempio' | tr '[:lower:]' '[:upper:]' Merge the contents of the upper and lower cells
• sed -e '1d' result.txt excludes the first line from the file example.txt
• sed -n '/stringa1/p' View only lines containing the word "string1"
• sed -e 's/ *$//' example.txt deletes the last blank character of each line
• sed -e 's/stringa1//g' example.txt removes only the word "string1" from the document and keeps the rest
• sed -n '1,5p;5q' example.txt View the content from the first line to the fifth line
• sed -n '5p;5q' example.txt View line 5
• sed -e 's/00*/0/g' example.txt replaces multiple zeros with a single zero
• cat -n file1 indicates the number of lines in the file
• cat example.txt | awk 'NR%2==1' deletes all even-numbered lines in the example.txt file
• echo abc | awk '{print $1}' View the first column of a line
• echo abc | awk '{print $1,$3}' View the first and third columns of a line
• paste file1 file2 Merge the contents of two files or two columns
• paste -d '+' file1 file2 Merge the contents of two files or two columns, separated by "+" in the middle
• sort file1 file2 Sort the contents of two files
• sort file1 file2 | uniq Take out the union of two files (only one copy of duplicate lines is kept)
• sort file1 file2 | uniq -u remove intersection, leave other lines
• sort file1 file2 | uniq -d Take out the intersection of two files (leave only files that exist in both files)
• comm -1 file1 file2 Compare the contents of two files and delete only the contents contained in 'file1'
• comm -2 file1 file2 Compare the contents of two files and delete only the contents contained in 'file2'
• comm -3 file1 file2 Compare the contents of two files and delete only the parts common to both files

Character setting and file format conversion

• dos2unix filedos.txt fileunix.txt converts 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 converts a text file into html
• recode -l | more show all allowed conversion formats

file system analysis

• badblocks -v /dev/hda1 Check for bad blocks on disk hda1
• fsck /dev/hda1 repair/check the integrity of the linux filesystem on the hda1 disk
• fsck.ext2 /dev/hda1 Repair/check the integrity of the ext2 filesystem on the hda1 disk
• e2fsck /dev/hda1 Repair/check the integrity of the ext2 filesystem on the hda1 disk
• e2fsck -j /dev/hda1 Repair/check the integrity of the ext3 filesystem on the hda1 disk
• fsck.ext3 /dev/hda1 Repair/check the integrity of the ext3 filesystem on the hda1 disk
• fsck.vfat /dev/hda1 Repair/check the integrity of the fat file system on the hda1 disk
• fsck.msdos /dev/hda1 repair/check the integrity of the dos file system on the hda1 disk
• dosfsck /dev/hda1 repair/check integrity of dos filesystem on disk hda1

initialize a file system

• mkfs /dev/hda1 creates a file system on the hda1 partition
• mke2fs /dev/hda1 creates a linux ext2 file system in the hda1 partition
• mke2fs -j /dev/hda1 Create a linux ext3 (journal) file system in the hda1 partition
• mkfs -t vfat 32 -F /dev/hda1 Create a FAT32 file system
• fdformat -n /dev/fd0 format a floppy disk
• mkswap /dev/hda3 creates a swap file system

SWAP file system

• mkswap /dev/hda3 creates a swap file system
• swapon /dev/hda3 enables a new swap filesystem
• swapon /dev/hda2 /dev/hdb3 enable two swap partitions

backup

• dump -0aj -f /tmp/home0.bak /home Make a full backup of the '/home' directory
• dump -1aj -f /tmp/home0.bak /home Make an interactive backup of the '/home' directory
• restore -if /tmp/home0.bak restore an interactive backup
• rsync -rogpav --delete /home /tmp to synchronize the directories on both sides
• rsync -rogpav -e ssh --delete /home ip_address:/tmp rsync via SSH channel
• 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 local directory to remote directory via ssh and compression
• dd bs=1M if=/dev/hda | gzip | ssh user@ip_addr 'dd of=hda.gz' Perform an operation of backing up the local disk on the remote host through ssh
• dd if=/dev/sda of=/tmp/file1 backup disk contents to a file
• tar -Puf backup.tar /home/user Perform an interactive backup of the '/home/user' directory
• ( cd /tmp/local/ && tar c . ) | ssh -C user@ip_addr 'cd /home/share/ && tar x -p' Copy a directory content in a remote directory via ssh
• ( tar c /home ) | ssh -C user@ip_addr 'cd /home/backup-home && tar x -p' Copy a local directory in a remote directory via ssh
• tar cf - . | (cd /tmp/backup ; tar xf - ) Copy a directory to another place locally, retaining the 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' from one directory to another
• find /var/log -name '*.log' | tar cv --files-from=- | bzip2 > log.tar.bz2 Find all files ending with '.log' and make a bzip package
• dd if=/dev/hda of=/dev/fd0 bs=512 count=1 Do an action to copy the content of MBR (Master Boot Record) to the floppy disk
• dd if=/dev/fd0 of=/dev/hda bs=512 count=1 restore MBR content from backup already saved to floppy

CD

• cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force Empty 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 CD-ROM iso image file 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
• mount -o loop cd.iso /mnt/iso Mount an ISO image file
• cd-paranoia -B rip tracks from a CD to wav files
• cd-paranoia - "-3" rip tracks from a CD disc to wav files (parameter -3)
• cdrecord --scanbus scan the bus to identify scsi channels
• dd if=/dev/hdc | md5sum Verify the md5sum encoding of a device, such as a CD

Network - (Ethernet and WIFI Wireless)

• ifconfig eth0 shows 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 configura 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 hostname of system
• host www.example.com lookup hostname to resolve name to ip address and viceversa
• nslookup www.example.com lookup hostname to resolve name to ip address and viceversa
• 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 viceversa
• nslookup www.example.com lookup hostname to resolve name to ip address and viceversa
• whois www.example.com lookup on Whois database

For details, please refer to the official sun documentation: Linux commands