Online Tools
Linux Commands - System Information
Command Code Notes
arch Display the processor architecture of the machine (1)
uname -m Displays the processor architecture of the machine (2)
uname -r Display the kernel version in use
dmidecode -q Show hardware system components - (SMBIOS / DMI)
hdparm -i /dev/hda List the architectural characteristics of a disk
hdparm -tT /dev/sda Performs a test read operation on a disk
cat /proc/cpuinfo Display information about CPU info
cat /proc/interrupts Display interrupts
cat /proc/meminfo Verify memory usage
cat /proc/swaps Shows which swaps are being used
cat /proc/version Show kernel version
cat /proc/net/dev Show network adapters and statistics
cat /proc/mounts Show loaded filesystems
lspci -tv List PCI devices
lsusb -tv Show USB devices
date Show system date
cal 2007 Show Calendar 2007
date 041217002007.00 Setting the Date and Time - Month Day Hour Minute Year. Seconds
clock -w Save time changes to BIOS
Linux Commands - System Shutdown (Shutdown, Reboot and Logout)
Command Code Explanation
shutdown -h now Shut down the system
init 0 Shuts down the system
telinit 0 Shuts down the system
shutdown -h hours:minutes & Shuts down the system at the scheduled time
shutdown -c Cancelling the scheduled shutdown of the system
shutdown -r now Reboot
reboot Reboot
logout Logout
Linux Commands - Files and Directories
Command Code Explanation
cd /home Go to '/ home' directory'
cd .. Return to the previous directory
cd ../.. Returns to the last two directories
cd Enter your home directory
cd ~user1 Go to your home directory
cd - Return to the last directory
pwd Show working path
ls Viewing files in a directory
ls -F Viewing files in a directory
ls -l Show file and directory details
ls -a Show hidden files
ls *[0-9]* Display file and directory names containing numbers
tree Displaying the tree structure of files and directories starting from the root directory
lstree Displaying 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 Create a directory tree
rm -f file1 Delete a file called 'file1''
rmdir dir1 delete a directory called 'dir1''
rm -rf dir1 Delete a directory called 'dir1' and its contents at the same time
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 in a directory to the current working directory.
cp -a /tmp/dir1 . Copy a directory to the current working directory
cp -a dir1 dir2 Copying a directory
ln -s file1 lnk1 Create a soft link to a file or directory
ln file1 lnk1 Create a physical link to a file or directory
touch -t 0712250000 file1 Modify the timestamp of a file or directory - (YYMMDDhhmm)
iconv -l List known encodings
iconv -f fromEncoding -t toEncoding inputFile > outputFile Change the encoding of a character
find . -maxdepth 1 -name *.jpg -print -exec convert Batch resize files in the current directory and send them to a thumbnail directory (requires conversion from ImageMagick)
Linux Commands - File Search
Command Code Note Explanation
find / -name file1 Search files and directories in the root file system starting from '/'.
find / -user user1 Search files and directories belonging to 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 that have not been used in the last 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 in '.rpm' and define their permissions
find / -xdev -name \*.rpm Search for files ending in '.rpm', ignoring removable devices such as CD-ROMs, JDs, etc.
locate \*.ps Search for files ending in '.ps' - run 'updatedb' first
whereis halt Show location of a binary file, source code or man
which halt Show the full path to a binary or executable file.
Linux Commands - Mounting a Filesystem
Command Code Explanation
mount /dev/hda2 /mnt/hda2 Mount a disk called hda2 - make sure the directory '/ mnt/hda2' already exists
umount /dev/hda2 Unmount a disc called hda2 - exit from mount point '/ mnt/hda2' first
fuser -km /mnt/hda2 Force uninstallation when device is busy
umount -n /mnt/hda2 Run the uninstall operation without writing to the /etc/mtab file - useful when the file is read-only or when the disc is written over
mount /dev/fd0 /mnt/floppy Mount a floppy disc
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
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 share
Linux Commands - Disk Space
Command Code Explanation
df -h Show the list of mounted partitions
ls -lSr |more Sort files and directories by size
du -sh dir1 Estimates the amount of space already used by the directory 'dir1'.
du -sk * | sort -rn Display files and directories by size.
rpm -q -a --qf '%10{SIZE}t%{NAME}n' | sort -k1,1n Show space used by installed rpm packages in order of size (fedora, redhat-like systems)
dpkg-query -W -f='${Installed-Size;10}t${Package}n' | sort -k1,1n Shows the space used by installed deb packages in order of size (ubuntu, debian-like systems).
Linux Commands - Users and Groups
Command Code Comments
groupadd group_name Creates a new user group
groupdel group_name Delete a usergroup
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 Creates a user belonging to the "admin" user group.
useradd user1 Create a new user
userdel -r user1 Delete a user ('-r' excludes home directories)
usermod -c "User FTP" -g system -d /ftp/user1 -s /bin/nologin user1 Modify user attributes
passwd Modify password
passwd user1 Modify a user's password (root only).
chage -E 2020-12-31 user1 Set the expiration date of a user's passphrase
pwck Check '/etc/passwd' for file format and syntax corrections, and existing users
grpck Check '/etc/passwd' for file formatting and syntax corrections and existing groups
newgrp group_name Log in to a new group to change the default group of the newly created file.
Linux Commands - File Permissions - Use "+" to set permissions, "-" to cancel them.
Command Code Explanation of comments
ls -lh Display permissions
ls /tmp | pr -T5 -W$COLUMNS Divide the terminal into 5 columns for display
chmod ugo+rwx directory1 Sets read (r), write (w) and execute (x) permissions for the owner (u), group (g) and others (o) of a directory.
chmod go-rwx directory1 Remove read, write, and execute permissions for groups (g) and others (o) on a directory.
chown user1 file1 Change the owner attribute of a file
chown -R user1 directory1 Change the owner attributes of a directory and change the attributes of all files in the directory.
chgrp group1 file1 Changing the group of a file
chown user1:group1 file1 Change the owner and group attributes of a file
find / -perm -u+s List all files on a system that are SUID controlled.
chmod u+s /bin/file1 Set the SUID bit of a binary file - the user running the file is given the same privileges as the owner
chmod u-s /bin/file1 Disable the SUID bit for a binary file
chmod g+s /home/public Set the SGID bit for a directory - similar to SUID, but directory-specific
chmod g-s /home/public Disable the SGID bit for a directory
chmod o+t /home/public Set the STIKY bit for a file - allows only legal owners to delete the file
chmod o-t /home/public Disable the STIKY bit for a directory
Linux Commands - Special Attributes of Files - Use "+" to set permissions, "-" to remove them.
Command Code Explanation of comments
chattr +a file1 Allow reading and writing to files only in append mode
chattr +c file1 Allows the file to be automatically compressed/decompressed by the kernel.
chattr +d file1 This file will be ignored by the dump program when making file system backups.
chattr +i file1 Set the file as immutable and cannot be deleted, modified, renamed or linked.
chattr +s file1 Allow a file to be securely deleted
chattr +S file1 As soon as an application performs a write operation on the file, cause the system to immediately write the result of the modification to disk.
chattr +u file1 If a file is deleted, the system will allow you to recover the deleted file at a later time.
lsattr Displaying Special Attributes
Linux Commands - Packing and Compressing Files
Command Code Explanation
bunzip2 file1.bz2 Unpacks a file called 'file1.bz2'.
bzip2 file1 Compress a file called 'file1
gunzip file1.gz Decompresses a file called 'file1.gz'.
gzip file1 Compresses 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 the directory 'dir1' at the same time
rar x file1.rar Decompress the rar package
unrar x file1.rar Decompressing a rar package
tar -cvf archive.tar file1 Create an uncompressed tarball
tar -cvf archive.tar file1 file2 dir1 Create an archive containing 'file1', 'file2' and 'dir1'.
tar -tf archive.tar Display the contents of a package
tar -xvf archive.tar Releasing a package
tar -xvf archive.tar -C /tmp Releases a tarball into the /tmp directory.
tar -cvfj archive.tar.bz2 dir1 Creates a bzip2 archive.
tar -jxvf archive.tar.bz2 Decompress a bzip2 archive
tar -cvfz archive.tar.gz dir1 Creates a gzip archive
tar -zxvf archive.tar.gz Decompress a gzip archive.
zip file1.zip file1 Create a zip archive
zip -r file1.zip file1 file2 dir1 Compresses several files and directories into a single zip archive.
unzip file1.zip Decompress a zip archive
Linux commands - RPM packages - (Fedora, Redhat and similar systems)
Command Code Explanation
rpm -ivh package.rpm Installing an rpm package
rpm -ivh --nodeeps package.rpm Installs an rpm package and ignores dependency warnings.
rpm -U package.rpm Update an rpm package without changing its configuration file.
rpm -F package.rpm Update an rpm package that is sure to be installed
rpm -e package_name.rpm Remove an rpm package
rpm -qa Show all installed rpm packages on the system
rpm -qa | grep httpd Show all rpm packages with the word "httpd" in their name.
rpm -qi package_name Get special information about an installed package
rpm -qg "System Environment/Daemons" Show rpm packages for a component
rpm -ql package_name Show the list of files provided by an installed rpm package
rpm -qc package_name Display a list of configuration files provided by an installed rpm package.
rpm -q package_name --whatrequires Display a list of dependencies on an rpm package.
rpm -q package_name --whatprovides Shows the size of an rpm package
rpm -q package_name --scripts Show scripts executed during installation/removal.
rpm -q package_name --changelog Show the modification history of an rpm package
rpm -qf /etc/httpd/conf/httpd.conf Confirms which rpm package provided the given file.
rpm -qp package.rpm -l Display a list of files provided by an uninstalled rpm package.
rpm --import /media/cdrom/RPM-GPG-KEY Import public key digital certificates
rpm --checksig package.rpm Verify the integrity of an rpm package
rpm -qa gpg-pubkey Verify the integrity of all installed rpm packages
rpm -V package_name Checks file size, licence, type, owner, group, MD5 check and last modification time.
rpm -Va Check all installed rpm packages on the system - use with care!
rpm -Vp package.rpm Verify that an rpm package is not installed
rpm2cpio package.rpm | cpio --extract --make-directories *bin* Run an executable from an rpm package
rpm -ivh /usr/src/redhat/RPMS/`arch`/package.rpm Installing a built package from an rpm source code
rpmbuild --rebuild package_name.src.rpm Building an rpm package from an rpm source code
Linux Commands - YUM Package Updater - (Fedora, RedHat and similar systems)
Command Code Notes
yum install package_name Download and install an rpm package
yum localinstall package_name.rpm Will install an rpm package, using your own repository to resolve all dependencies for you
yum update package_name.rpm Updates all installed rpm packages on 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 on the system
yum search package_name Search for packages in the rpm repository
yum clean packages Clear rpm cache to remove downloaded packages
yum clean headers Remove all header files
yum clean all Remove all cached packages and headers
Linux Commands - DEB Packages (Debian, Ubuntu and similar systems)
Command Code Notes
dpkg -i package.deb Installs/updates a deb package
dpkg -r package_name Remove a deb package from the system
dpkg -l Show all installed deb packages on the system
dpkg -l | grep httpd Displays all deb packages whose names contain the word "httpd".
dpkg -s package_name Get information about a particular package already installed on the system
dpkg -L package_name Show the list of files provided by a deb package that is already installed on the system.
dpkg --contents package.deb Show the list of files provided by a package that has not yet been installed.
dpkg -S /bin/ping Confirms which deb package provides the given file.
Linux commands - APT Software Tools (Debian, Ubuntu and similar)
Command Code Explanation of comments
apt-get install package_name Install/update a deb package
apt-cdrom install package_name Install/update a deb package from a disc
apt-get update Upgrade packages in the list
apt-get upgrade Upgrade all installed software
apt-get remove package_name Remove a deb package from the system
apt-get check Confirm the correct repositories for dependencies
apt-get clean Clear cache from downloaded packages
apt-cache search searched-package Return the package name that contains the search string you want
Linux Commands - Viewing File Contents
Command Code Explanation
cat file1 View the contents of a file in the forward direction starting from the first byte.
tac file1 View the contents of a file in reverse from the last line.
more file1 View the contents of a long file
less file1 Similar to the 'more' command, but it allows the same reverse operation as the forward operation in a 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 View the contents of a file as it is added in real time.
Linux Commands - Text Processing
Command Code Annotate Description
cat file1 | command( sed, grep, awk, grep, etc...) > result.txt Merge the detailed description text of a file and write the description to a new file
cat file1 | command( sed, grep, awk, grep, etc...) >> result.txt Merges the text of a file's description and writes the description to an existing file.
grep Aug /var/log/messages Find the keyword "Aug" in the file '/var/log/messages'.
grep ^Aug /var/log/messages Look for words starting with "Aug" in the file '/var/log/messages'.
grep [0-9] /var/log/messages Select all lines in the file '/var/log/messages' that contain numbers
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" with "string2" in the example.txt file.
sed '/^$/d' example.txt Delete all blank lines from example.txt file
sed '/ *#/d; /^$/d' example.txt Remove all comments and blank lines from example.txt Remove all comments and blank lines from example.txt
echo 'esempio' | tr '[:lower:]' '[:upper:]' Merge top and bottom cells
sed -e '1d' result.txt Exclude the first line from the example.txt file
sed -n '/stringa1/p' View lines containing only the word "string1".
sed -e 's/ *$//' example.txt Remove blank characters at the end of each line
sed -e 's/stringa1//g' example.txt Remove only the word "string1" from the document and keep all the rest.
sed -n '1,5p;5q' example.txt View the content from line 1 to line 5
sed -n '5p;5q' example.txt View line 5
sed -e 's/00*/0/g' example.txt Replace multiple zeros with a single zero
cat -n file1 Mark the number of lines in the file
cat example.txt | awk 'NR%2==1' Delete all even lines in example.txt file
echo a b c | awk '{print $1}' View the first column of a row
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 two columns
paste -d '+' file1 file2 Merge the contents of two files or two columns, separated by a "+".
sort file1 file2 Sort the contents of two files
sort file1 file2 | uniq Take out the union of the two files (keep only one copy of the duplicate rows).
sort file1 file2 | uniq -u Delete the intersection, leaving the other lines
sort file1 file2 | uniq -d Remove the intersection of the two files (leaving only the files that exist in both files).
comm -1 file1 file2 Compare the contents of two files removing only the contents of 'file1'.
comm -2 file1 file2 Compare the contents of two files and delete only the contents of 'file2'.
comm -3 file1 file2 Comparing two files removes only the parts that are common to both files.
Linux Commands - Character Setting and File Format Conversion
Command Code Explanation
dos2unix filedos.txt fileunix.txt Converts the format of a text file from MSDOS to UNIX.
unix2dos fileunix.txt filedos.txt Converts a text file from UNIX to MSDOS.
recode ..HTML page.html Convert a text file to html
recode -l | more Show all allowed conversion formats
Linux Commands - File System Analysis
Command Code Explanation of comments
badblocks -v /dev/hda1 Check for bad blocks on disk hda1
fsck /dev/hda1 Repair/check integrity of linux filesystem on disk hda1
fsck.ext2 /dev/hda1 Repair/check integrity of ext2 file system on disk hda1
e2fsck /dev/hda1 Repair/check integrity of 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 integrity of ext3 file system on hda1 disc
fsck.vfat /dev/hda1 Repair/check integrity of fat file system on hda1 disc
fsck.msdos /dev/hda1 Repair/check integrity of dos file system on hda1 disc
dosfsck /dev/hda1 Repair/check the integrity of the dos filesystem on disk hda1
Linux Command - Initialise a File System
Command Code Notes
mkfs /dev/hda1 Create a file system on hda1 partition
mke2fs /dev/hda1 Create a linux ext2 filesystem on hda1 partition
mke2fs -j /dev/hda1 Creates a linux ext3 (journaling) file system on partition hda1.
mkfs -t vfat 32 -F /dev/hda1 Create a FAT32 file system
fdformat -n /dev/fd0 Format a floppy disc
mkswap /dev/hda3 Creating a swap filesystem
Linux Commands - SWAP Filesystem
Command Code Explanation
mkswap /dev/hda3 Create a swap file system
swapon /dev/hda3 Enables a new swap file system
swapon /dev/hda2 /dev/hdb3 Enable two swap partitions
Linux Commands - Backup
Command Code Notes
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 Synchronise the two directories
rsync -rogpav -e ssh --delete /home ip_address:/tmp rsync over SSH channel
rsync -az -e ssh --delete ip_addr:/home/public /home/local Sync a remote directory to a local directory via ssh and compression
rsync -az -e ssh --delete /home/local ip_addr:/home/public Sync 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 a local disc on a remote host via ssh
dd if=/dev/sda of=/tmp/file1 Backing up the contents of a disc 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' Copying the contents of a directory 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 to a remote directory via ssh
tar cf - . | (cd /tmp/backup ; tar xf - ) Locally copy a directory to another location, preserving permissions and links
find /home/user1 -name '*.txt' | xargs cp -av --target-directory=/home/backup/ --parents Find and copy all files ending in '.txt' from one directory to another directory
find /var/log -name '*.log' | tar cv --files-from=- | bzip2 > log.tar.bz2 Find all files ending in '.log' and make a bzip package of them
dd if=/dev/hda of=/dev/fd0 bs=512 count=1 Do a copy of the MBR (Master Boot Record) contents to a floppy disc
dd if=/dev/fd0 of=/dev/hda bs=512 count=1 Restore the MBR contents from a backup that has been saved to a floppy.
Linux Commands - CD-ROM
Command Code Explanation
cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force Empties the contents of a rewritable disc
mkisofs /dev/cdrom > cd.iso Creates an iso image of the disc on the disk.
mkisofs /dev/cdrom | gzip > cd_iso.gz Creates a compressed iso image of a disc on a disk.
mkisofs -J -allow-leading-dots -R -V "Label CD" -iso-level 4 -o ./cd.iso data_cd Creates an iso image 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 Extract audio tracks from a CD disc to a wav file
cd-paranoia -- "-3" Extract tracks from a CD disc to a wav file (parameter -3)
cdrecord --scanbus Scan the bus to identify scsi channels
dd if=/dev/hdc | md5sum Verify the md5sum encoding of a device, e.g. a CD
Linux commands - network - (Ethernet and WIFI wireless)
Command code Note Explanation
dhclient eth0 Enable 'eth0' network device in dhcp mode
ethtool eth0 Show traffic statistics for network card 'eth0'
host www.example.com Find hostnames to resolve names with IP addresses and mirrors
hostname Display hostnames
ifconfig eth0 Display the configuration of an Ethernet card
ifconfig eth0 192.168.1.1 netmask 255.255.255.0 Controlling IP Addresses
ifconfig eth0 promisc Set 'eth0' to promiscuous mode for packet sniffing
ifdown eth0 Disable an 'eth0' network device
ifup eth0 Enable an 'eth0' network device
ip link show Display the connection status of all network devices
iwconfig eth1 Display the configuration of a wireless card
iwlist scan Show wireless networks
mii-tool eth0 Show the connection status of 'eth0'
netstat -tup Show all enabled network connections and their PIDs
netstat -tup1 Show all listening network services on the system and their PIDs.
netstat -rn Display the routing table, similar to the "route -n" command.
nslookup www.example.com Finds hostnames to resolve names and IP addresses and mirrors them.
route -n Display the routing table
route add -net 0/0 gw IP Gateway Controlling Predefined Gateways
route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1 Control static routes to network '192.168.0.0/16'.
route del 0/0 gw IP gateway Delete static routes
echo “1”> /proc/sys/net/ipv4/ip_foward Activate IP Forwarding
tcpdump tcp port 80 Show all HTTP loops
whois www.example.com Lookup in Whois database
Linux Commands - Microsoft Windows Network
Command Code Note Explanation
mount -t smbfs -o username=user,password=pass //WinClient/share/mnt/share Mount a windows network share
nbtscan ip addr netbios name resolution
nmblookup -A ip addr netbios name resolution
smbclient -L ip addr/hostname Show remote share of a windows host
smbget -Rr smb://ip addr/share Download files from a windows host via smb like wget.
Linux Commands - IPTABLES(firewall)
Command Code Explanation
iptables -t filter -L Displays all links in the filter table
iptables -t nae -L Displays all links in the nat table
iptables -t filter -F Clean up all rules based on the filter table
iptables -t nat -F Clears all rules based on the nat table
iptables -t filter -X Delete all links created by the user
iptables -t filter -A INPUT -p tcp --dport telnet -j ACCEPT Allow telnet access
iptables -t filter -A OUTPUT -p tcp --dport telnet -j DROP Block telnet access
iptables -t filter -A FORWARD -p tcp --dport pop3 -j ACCEPT Allow forwarding of POP3 connections on links
iptables -t filter -A INPUT -j LOG --log-prefix Log all packets blocked on the link
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE Set up a PAT (Port Address Translation) to mask outgoing packets at eth0
iptables -t nat -A POSTROUTING -d 192.168.0.1 -p tcp -m tcp --dport 22-j DNAT --to-destination 10.0.0.2:22 Divert packets destined for one host address to other hosts
Linux Commands - Monitoring and Debugging
Command Code Notes
free -m List RAM status in megabytes
kill -9 process id Force a process to shut down and end it
kill -1 process id Force a process to reload its configuration
last reboot Show reboot history
lsmod List the status of kernel modules
lsof -p process id List a list of files opened by a process
lsof /home/user1 List opened files in the given system paths
ps -eafw List linux tasks
ps -e -o pid,args --forest List linux tasks in a hierarchical way.
pstress Display processes in a tree view
smartctl -A /dev/hda Monitor the reliability of a hard disc device by enabling SMART.
smartctl -i /dev/hda Checks whether SMART is enabled for a hard disc device.
strace -c ls >/dev/null List system calls made and received by a process
strace -f -e open ls >/dev/null List library calls
tail /var/log/dmesg Display internal events during kernel boot
tail /val/log/messages Show system events
top List the linux tasks that use the most CPU resources
watch -nl ‘cat /proc/interrupts’ List real-time interrupts
Linux commands - other common commands
Command Code Notes
alias hh='history' Set an alias for the command history.
apropos ...keyword Make a list of commands with program keywords, especially useful if you only know what the program does and don't remember the commands
chsh Changing shell commands
chsh --list-shells A nice command for finding out if you have to connect remotely to another machine.
gpg -c filel Encrypt a file with GNU Privacy Guard
gpg filel.gpg Decrypt a file with GNU Privacy Guard.
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