Linux Commands - System Information and Monitoring

Clear terminal screen

Clears the terminal screen, just like the shortcut Control + L.

clear

Reset terminal session

Resets the current terminal session.

reset

End terminal session

Closes the local or remote (SSH) terminal session and terminates initiated processes.

exit

Show running tasks

Displays a list of running tasks and their resource usage.

top

Show tasks with enhanced resources

Displays more detailed and visual information about running tasks.

htop

RAM status

Displays the status of RAM in megabytes.

free -h

List mounted partitions

Displays a list of the partitions mounted on the system.

df -h

View partition information on the system

Displays information about the partitions and their usage.

lsblk

Size of files and directories

Displays the size of files and directories sorted by size.

ls -lSr | more

Space used by a directory

Estimates the space used by the directory dir1.

du -sh directory

Size sorted of files and directories

Displays the size of files and directories sorted by size.

du -sk * | sort -rn

Data of connected users

Displays information about users connected to the system.

who -a

View CPU usage details

Displays CPU usage details for each core.

mpstat -P ALL

Reboot history

Displays the system’s reboot history.

last reboot

System architecture and version

Displays the architecture and version of Linux and the kernel.

uname -a

Loaded kernel

Displays the currently loaded kernel.

lsmod

System hardware components

Displays information about the system hardware.

dmidecode -q

List hard drive partitions

Displays the partitions configured on the system.

cat /etc/fstab

Hard drive features

Displays specific features of the hard drive.

hdparm -i /dev/hda

Show PCI devices

Displays a list of connected PCI devices.

lspci

Show USB devices

Lists the USB devices connected to the system.

lsusb

Kernel loading process events

Displays events during the kernel loading.

tail /var/log/dmesg

System events

Displays logged system events.

tail /var/log/messages

Open files by processes

Displays the list of open files by the current process.

lsof -p $$

Open files in a directory

Displays open files in a specific directory.

lsof /directory

System calls

Displays the system calls made by a process.

strace -c ls >/dev/null

Library calls

Displays the library calls of a specific process.

strace -f -e open ls >/dev/null

Real-time interrupts

Displays system interrupts in real time.

watch -n1 'cat /proc/interrupts'

Log out user

Ends the current user’s session.

logout

Shut down the system

Shuts down the system immediately.

shutdown now

Restart the system

Restarts the system immediately.

shutdown -r now

Scheduled shutdown

Schedules a shutdown for a specific hour and minute.

shutdown hours:minutes &

Cancel scheduled shutdown

Cancels a scheduled shutdown.

shutdown -c

Show system date

Displays the current system date.

date

Year calendar

Displays the calendar for a specific year.

cal year

Month and year calendar

Displays the calendar for a specific month and year.

cal month year