HTTP request method comparison table, HTTP request method collection

Linux Commands — System Information

Command code	Notes
arch	Display the processor architecture of the machine (1)
uname -m	Display the processor architecture of the machine (2)
uname -r	Show the kernel version in use
dmidecode -q	Display hardware system components - (SMBIOS / DMI)
hdparm -i /dev/hda	List the architectural features of a disk
hdparm -tT /dev/sda	Perform test read operations on disk
cat /proc/cpuinfo	Display CPU info information
cat /proc/interrupts	Display interrupt
cat /proc/meminfo	Verify memory usage
cat /proc/swaps	Show which swaps are used
cat /proc/version	Show the kernel version
cat /proc/net/dev	Display network adapters and statistics
cat /proc/mounts	Show loaded file system
lspci -tv	List PCI devices
lsusb -tv	Show USB devices
date	Show system date
cal 2007	Show calendar for 2007
date 041217002007.00	Set date and time - month, day, time, year. seconds
clock -w	Save time modification to BIOS

Linux commands — system shutdown (shutdown, restart and logout)

Command code	Notes
shutdown -h now	Turn off the system
init 0	Turn off the system
telinit 0	Turn off the system
shutdown -h hours:minutes &	Turn off the system at the scheduled time
shutdown -c	Cancel shut down the system at the scheduled time
shutdown -r now	Restart
reboot	Restart
logout	Log out

Linux Commands — Files and Directories

Command code	Notes
cd /home	Go to the '/home' directory'
cd ..	Return to the previous directory
cd ../..	Return to the previous two-level directory
cd	Enter your personal home directory
cd ~user1	Enter your personal home directory
cd -	Return to the directory you were in the last time
pwd	Show work path
ls	View files in the directory
ls -F	View files in the directory
ls -l	Display detailed information of files and directories
ls -a	Show hidden files
ls [0-9]	Show file names 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	Create a directory called 'dir1'
mkdir dir1 dir2	Create 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 delete its contents at the same time
rm -rf dir1 dir2	Delete two directories and their contents at the same time
mv dir1 new_dir	Rename/move a directory
cp file1 file2	Copy a file
cp dir/* .	Copy all files in one 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 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 characters
find . -maxdepth 1 -name *.jpg -print -exec convert	Batch resize the file in the current directory and send it to the thumbnail directory (need to be converted from ImageMagick)

Linux Commands — File Search

Command code	Notes
find / -name file1	Starting from '/', enter the root file system to search for files and directories
find / -user user1	Search for files and directories belonging to user 'user1'
find /home/user1 -name \*.bin	Search for a file ending with '.bin' in directory '/home/user1'
find /usr/bin -type f -atime +100	Search for execution files that have not been used in the past 100 days
find /usr/bin -type f -mtime -10	Search for files that have been 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 optical drives and shortcuts
locate \*.ps	Looking for files ending with '.ps' - Run the 'updatedb' command first
whereis halt	Displays the location of a binary file, source code, or man
which halt	Shows the full path to a binary or executable file

Linux commands — Mount a file system

Command code	Notes
mount /dev/hda2 /mnt/hda2	Mount a disk called hda2 - Confirm the directory '/mnt/hda2' already exists
umount /dev/hda2	Uninstall a disk called hda2 - Exit from the mount point '/mnt/hda2'
fuser -km /mnt/hda2	Forced uninstall when the 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 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

Linux Commands — Disk Space

Command code	Notes
df -h	Shows the mounted partition list
ls -lSr \|more	Arrange files and directories by size
du -sh dir1	Estimate the disk space already used by directory 'dir1'
du -sk * \| sort -rn	Display the size of files and directories in sequence based on capacity size
rpm -q -a --qf '%10{SIZE}t%{NAME}n' \| sort -k1,1n	Display the space used by installed rpm packages in sequence based on size (fedora, redhat class system)
dpkg-query -W -f='${Installed-Size;10}t${Package}n' \| sort -k1,1n	Display the space used by the installed deb package based on size (ubuntu, debian system)

Linux Commands — Users and Groups

Command code	Notes
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' exclude home directory)
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 (only root is allowed to execute)
chage -E 2020-12-31 user1	Set the expiration period of user password
pwck	Check the file format and syntax correction of '/etc/passwd' and the existing users
grpck	Check the file format and syntax corrections of '/etc/passwd' and the existing groups
newgrp group_name	Log in to a new group to change the preset group of newly created files

Linux commands — file permissions - use "+" to set permissions, use "-" to cancel

Command code	Notes
ls -lh	Show permissions
ls /tmp \| pr -T5 -W$COLUMNS	Divide the terminal into 5 columns to display
chmod ugo+rwx directory1	Set permissions for everyone (u), group (g) and others (o) of the directory to read (r), write (w) and execute (x)
chmod go-rwx directory1	Delete group (g) and others (o) read and write execution permissions to directories
chown user1 file1	Change the properties of a file
chown -R user1 directory1	Change the properties of all files in a directory and change the properties of all files in the directory at the same time
chgrp group1 file1	Change the group of files
chown user1:group1 file1	Change the owner and group properties of a file
find / -perm -u+s	List all files in a system that use SUID control
chmod u+s /bin/file1	Set the SUID bit of a binary file - the user running the file is also given the same permissions as the owner
chmod u-s /bin/file1	Disable the SUID bit of a binary file
chmod g+s /home/public	Set the SGID bit of a directory - similar to SUID, but this is for the directory
chmod g-s /home/public	Disable the SGID bits of a directory
chmod o+t /home/public	Set the STIKY bit of a file - Only legal everyone can delete files
chmod o-t /home/public	Disable the STIKY bit of a directory

Linux commands — special properties of files - use "+" to set permissions, use "-" to cancel

Command code	Notes
chattr +a file1	Only read and write files in append mode are allowed
chattr +c file1	Allows this file to be automatically compressed/decompressed by the kernel
chattr +d file1	When performing file system backup, the dump program ignores this file
chattr +i file1	Files that are set to immutable cannot be deleted, modified, renamed or linked
chattr +s file1	Allow a file to be deleted safely
chattr +S file1	Once the application performs a write operation on 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 restore the deleted file in the future.
lsattr	Show special properties

Linux Commands - Packaging and Compressing Files

Command code	Notes
bunzip2 file1.bz2	Unzip a file called 'file1.bz2'
bzip2 file1	Compress a file called 'file1'
gunzip file1.gz	Unzip a file called 'file1.gz'
gzip file1	Compress a file called 'file1'
gzip -9 file1	Maximum compression
rar a file1.rar test_file	Create a package called 'file1.rar'
rar a file1.rar file1 file2 dir1	Compress 'file1', 'file2' and directory 'dir1' at the same time
rar x file1.rar	Unzip rar package
unrar x file1.rar	Unzip rar package
tar -cvf archive.tar file1	Create a non-compressed tarball
tar -cvf archive.tar file1 file2 dir1	Create an archive file containing 'file1', 'file2' and 'dir1'
tar -tf archive.tar	Show contents in a package
tar -xvf archive.tar	Release a package
tar -xvf archive.tar -C /tmp	Release the compressed package into /tmp directory
tar -cvfj archive.tar.bz2 dir1	Create a bzip2 format compressed package
tar -jxvf archive.tar.bz2	Unzip a compressed package in bzip2 format
tar -cvfz archive.tar.gz dir1	Create a gzip compressed package
tar -zxvf archive.tar.gz	Unzip a gzip 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 at the same time
unzip file1.zip	Unzip a zip format compressed package

Linux commands — RPM packages - (Fedora, Redhat and similar systems)

Command code	Notes
rpm -ivh package.rpm	Install a rpm package
rpm -ivh --nodeeps package.rpm	Install an rpm package and ignore dependency warning
rpm -U package.rpm	Update an rpm package without changing its configuration file
rpm -F package.rpm	Update a rpm package that is sure to have been installed
rpm -e package_name.rpm	Delete a rpm package
rpm -qa	Display all installed rpm packages in the system
rpm -qa \| grep httpd	Show all rpm packages with the word "httpd" in their names
rpm -qi package_name	Get special information about an installed package
rpm -qg "System Environment/Daemons"	Displays a component's rpm package
rpm -ql package_name	Shows 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	Shows 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/deletion
rpm -q package_name --changelog	Shows the modification history of an rpm package
rpm -qf /etc/httpd/conf/httpd.conf	Confirm which rpm package is provided by the given file
rpm -qp package.rpm -l	Shows a list of files provided by a rpm package that has not been installed yet
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	Check all installed rpm packages in the system - use with caution
rpm -Vp package.rpm	Confirm that a rpm package has not been installed yet
rpm2cpio package.rpm \| cpio --extract --make-directories bin	Run an executable from a rpm package
rpm -ivh /usr/src/redhat/RPMS/`arch`/package.rpm	Install a built package from a rpm source code
rpmbuild --rebuild package_name.src.rpm	Build an rpm package from a rpm source

Linux Commands — YUM Package Upgrade - (Fedora, RedHat and similar systems)

Command code	Notes
yum install package_name	Download and install an rpm package
yum localinstall package_name.rpm	A rpm package will be installed and all dependencies will be resolved for you using your own repository
yum update package_name.rpm	Update all installed rpm packages in the current system
yum update package_name	Update a rpm package
yum remove package_name	Delete a rpm package
yum list	List all packages installed in the current system
yum search package_name	Search for packages in rpm repository
yum clean packages	Clean up rpm cache to delete downloaded packages
yum clean headers	Delete all header files
yum clean all	Delete all cached packages and header files

Linux commands — DEB packages (Debian, Ubuntu and similar systems)

Command code	Notes
dpkg -i package.deb	Install/update a deb package
dpkg -r package_name	Delete a deb package from the system
dpkg -l	Display all installed deb packages in the system
dpkg -l \| grep httpd	Show all deb packages with the word "httpd" in their names
dpkg -s package_name	Get information about a special package that has been installed in the system
dpkg -L package_name	Displays the file list provided by a deb package that has been installed in the system
dpkg --contents package.deb	Shows a list of files provided by a package that has not been installed yet
dpkg -S /bin/ping	Confirm which deb package is provided by the given file

Linux Commands — APT Software Tools (Debian, Ubuntu and similar systems)

Command code	Notes
apt-get install package_name	Install/update a deb package
apt-cdrom install package_name	Install/update a deb package from the disc
apt-get update	Upgrade the packages in the list
apt-get upgrade	Upgrade all installed software
apt-get remove package_name	Delete a deb package from the system
apt-get check	Confirm that the dependent repository is correct
apt-get clean	Clean cache from downloaded package
apt-cache search searched-package	Returns the package name containing the string you want to search for

Linux commands — view file content

Command code	Notes
cat file1	Starting from the first byte, the contents of the file are viewed forward
tac file1	Starting from the last line, view the contents of a file in reverse
more file1	View the contents of a long file
less file1	Similar to the 'more' command, but it allows reverse operations in 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 content added to a file in real time

Linux Commands — Text Processing

Command code	Notes
cat file1 \| command( sed, grep, awk, grep, etc...) > result.txt	Merge the detailed description text of a file and write the introduction into a new file
cat file1 \| command( sed, grep, awk, grep, etc...) >> result.txt	Merge the detailed description text of a file and write the introduction into an existing file
grep Aug /var/log/messages	Find keyword "Aug" in file '/var/log/messages'
grep ^Aug /var/log/messages	Find vocabulary starting with "Aug" in file '/var/log/messages'
grep [0-9] /var/log/messages	Select '/var/log/messages' all lines containing numbers in the file
grep Aug -R /var/log/*	Search 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 '/^$/d' example.txt	Remove all blank lines from example.txt file
sed '/ *#/d; /^$/d' example.txt from example.txt	Delete all comments and blank lines in the file
echo 'esempio' \| tr '[:lower:]' '[:upper:]'	Merge upper and lower cell contents
sed -e '1d' result.txt	Exclude the first line from the file example.txt
sed -n '/stringa1/p'	View lines that contain only the word "string1"
sed -e 's/ *$//' example.txt	Delete the last whitespace character of each line
sed -e 's/stringa1//g' example.txt	Remove only the vocabulary "string1" from the document and keep all remaining
sed -n '1,5p;5q' example.txt	View 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	Number of lines indicating the file
cat example.txt \| awk 'NR%2==1'	Delete all even lines in the 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 row
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, and use "+" to distinguish them 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 the duplicate lines)
sort file1 file2 \| uniq -u	Delete the intersection, leaving other lines
sort file1 file2 \| uniq -d	Take out the intersection of two files (leave only files that exist in both files at the same time)
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 shared by the two files.

Linux Commands — Character Settings and File Format Conversion

Command code	Notes
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	Show all allowed conversion formats

Linux Commands — File System Analysis

Command code	Notes
badblocks -v /dev/hda1	Check for bad blocks on disk hda1
fsck /dev/hda1	Fix/check the integrity of the linux file system on hda1 disk
fsck.ext2 /dev/hda1	Fix/check the integrity of ext2 file system on hda1 disk
e2fsck /dev/hda1	Fix/check the integrity of ext2 file system on hda1 disk
e2fsck -j /dev/hda1	Fix/check the integrity of ext3 file system on hda1 disk
fsck.ext3 /dev/hda1	Fix/check the integrity of ext3 file system on hda1 disk
fsck.vfat /dev/hda1	Fix/check the integrity of the fat file system on hda1 disk
fsck.msdos /dev/hda1	Fix/check the integrity of the dos file system on hda1 disk
dosfsck /dev/hda1	Fix/check the integrity of the dos file system on hda1 disk

Linux Commands — Initialize a file system

Command code	Notes
mkfs /dev/hda1	Create a file system in hda1 partition
mke2fs /dev/hda1	Create a linux ext2 file system in hda1 partition
mke2fs -j /dev/hda1	Create a linux ext3 (log type) file system in 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	Create a swap file system

Linux Commands — SWAP File System

Command code	Notes
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 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	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 through ssh and compression
rsync -az -e ssh --delete /home/local ip_addr:/home/public	Synchronize local directories to remote directories via ssh and compression
dd bs=1M if=/dev/hda \| gzip \| ssh user@ip_addr 'dd of=hda.gz'	Perform a backup of local disks on a remote host via ssh
dd if=/dev/sda of=/tmp/file1	Backup disk contents to a file
tar -Puf backup.tar /home/user	Perform an interactive backup operation to 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 - )	Locally copy one directory to another place, 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 MBR (Master Boot Record) content to the floppy disk
dd if=/dev/fd0 of=/dev/hda bs=512 count=1	Recover MBR content from backups that have been saved to floppy disk

Linux commands — CD-ROM

Command code	Notes
cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force	Clear a rewriteable CD content
mkisofs /dev/cdrom > cd.iso	Create a disc's iso image file on disk
mkisofs /dev/cdrom \| gzip > cd_iso.gz	Create a compressed disc 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 for 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	Transcribing the audio track from a CD to a wav file
cd-paranoia -- "-3"	Transcribing the track from a CD disc to a wav file (parameter-3)
cdrecord --scanbus	Scan the bus to identify the scsi channel
dd if=/dev/hdc \| md5sum	Verify the md5sum encoding of a device, such as a CD

Linux Commands — Network - (Ethernet and WIFI wireless)

Command code	Notes
dhclient eth0	Enable 'eth0' network device in dhcp mode
ethtool eth0	Display traffic statistics of network card ‘eth0’
host www.example.com	Find the host name to resolve the name and IP address and image
hostname	Show host name
ifconfig eth0	Displays the configuration of an Ethernet card
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)
ifdown eth0	Disable an 'eth0' network device
ifup eth0	Enable an 'eth0' network device
ip link show	Displays the connection status of all network devices
iwconfig eth1	Displays the configuration of a wireless network card
iwlist scan	Show wireless network
mii-tool eth0	Shows the connection status of 'eth0'
netstat -tup	Show all enabled network connections and their PIDs
netstat -tup1	Displays all listening network services and their PIDs in the system
netstat -rn	Display routing table, similar to the "route -n" command
nslookup www.example.com	Find the host name to resolve the name and IP address and image
route -n	Show routing table
route add -net 0/0 gw IP Gateway	Control the preset gateway
route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1	Control static routes to the 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 loopbacks
whois www.example.com	Find in Whois database

Linux Commands — Microsoft Windows Network

Command code	Notes
mount -t smbfs -o username=user,password=pass //WinClient/share/mnt/share	Mount a Windows network share
nbtscan ip addr	Netbios name analysis
nmblookup -A ip addr	Netbios name analysis
smbclient -L ip addr/hostname	Show remote sharing of a windows host
smbget -Rr smb://ip addr/share	Like wget, you can download files from a windows host via smb

Linux commands — IPTABLES(firewall)

Command code	Notes
iptables -t filter -L	Show all links in the filter table
iptables -t nae -L	Show all links in the nat table
iptables -t filter -F	Clean all rules based on filter tables
iptables -t nat -F	Clean all rules based on nat table
iptables -t filter -X	Delete all links created by users
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 POP3 connections on forwarding links
iptables -t filter -A INPUT -j LOG --log-prefix	Record all the packets seized in the links
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE	Set a PAT (port address translation) to mask out packets in 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	Transfer packets sent to one host address to another host

Linux Commands — Monitoring and Debugging

Command code	Notes
free -m	List RAM status in megabytes
kill -9 process id	Forcefully close the process and end it
kill -1 process id	Force a process to overload its configuration
last reboot	Show restart history
lsmod	Kernel modules that list states
lsof -p process id	List a list of files opened by a process
lsof /home/user1	List the list of opened files in the given system path
ps -eafw	List Linux tasks
ps -e -o pid,args --forest	List Linux tasks in a hierarchical way
pstress	Show program in a tree diagram
smartctl -A /dev/hda	Monitor the reliability of hard drive devices by enabling SMART
smartctl -i /dev/hda	Check if SMART of a hard disk device is enabled
strace -c ls >/dev/null	List the system calls made and receive them with 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	List a list of commands that include program keywords, which is especially useful when you only know what the program does and don't remember commands.
chsh	Change shell command
chsh --list-shells	Good commands to find out if you have to connect to another machine remotely
gpg -c filel	Encrypt a file with GNU Privacy Guard
gpg filel.gpg	Decrypt a file using GNU Privacy Guard