We begin with some commands to get system information: kernel features and architecture.
arch # architecture uname -m # architecture uname -r # kernel version uname -a #complete information cat /etc/issue # distribution name
Recall that in Linux, everything is stored in files, so if we want to see a detailed system information, "/proc" directory will be of much help, because it contains the files hierarchy that shows the current state of the kernel. Within this directory you can find a lot of information about the hardware and any processes running. If you enter to this directory, and you see that files have 0 bytes, do not worry it's normal, because the "/proc" directory contains another file type called virtual files, unlike the known types: text and binary files, that you will be more familiarized. Here are some examples:
cat /proc/cpuinfo # CPU information cat /proc/interrupts # show interruptions cat /proc/meminfo # verify memory usage cat /proc/mounts # show mounted filesystem cat /proc/swaps # show swap cat /proc/version # kernel version cat /proc/net/dev # show network adapters and statistics lspci -tv # show PCI devices lsusb -tv # show USB devices
On the other hand, if you want a real-time monitor system, the following command is the indicated. When you are using it you can type some options: h - help, u – user, p - PID, q - exit.
top # show Linux tasks
For dates, schedules and time, also we have two useful commands:
date # show system date date 041217002011.00 # set date and time cal 2011 # show 2011 schedule cal 02 2009 # show february 2009 schedule clock -w # save date changes in BIOS
To view the disk space consumption, directories or files, we can use different commands like "ls", "df" and "du". Below we combine them with other commands to optimize viewing:
ls -lSr | more # show file and directories sorted by size df -h # partitions list du -sh dir1 # used space by dir1 du -h --max-depth=1 | sort -nr # show size of all subdirectories in the current location in descending order du -sk * | sort -rn # show file and directories sorted by size
Finally, shutdown, restart or log off:
shutdown -h 23:17 # scheduled shutdown at 23:17 shutdown -c # cancel a scheduled shutdown shutdown -h now # shutdown shutdown -r now # restart halt # shutdown poweroff # shutdown reboot # restart logout # log out
- Red Hat Enterprise Linux: Reference Manual