4: Operating System Commands
- Page ID
- 469638
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Operating System Commands
date
date date +%m-%d-%y
df - free space
Display Partitions (free space)
To make the output easier to understand (in Kilobytes, Megabytes and Gigabytes), use the option -h (human-readable) with the df command
To know the storage usage of each folder, use the command:
df df -h
- Output:
-
du - disk usage
To know how much storage has been used from the disk, use the command:
- du : disk usage
-
du du/home/pi
for a specific directory (home/pi)
By using the du command by itself, be ready to get a big number of logs with all the files that exist on your disk!
We will be discussing the options to get precise outputs using the du command in the following part.
To know the storage usage of each folder, use the command:
du -h --max-depth=1 ./
- Output:
-
dmesg
displays kernel related messages about hardware, device drivers, initialization and bootup issues
In this activity we will check bootup processes and errors
dmesg
- Output:
-
free
To know how much RAM the server has, use the command:
- free
- free -b : b is for bytes
- free -k : k is for kilo-bytes
- free -m : m is for mega-bytes
- free -g : g is for giga_bytes
free free -b
- Output:
-
htop
Monitor running processes
In this activity we will check bootup processes and errors (you need to use ctrl c to terminate
htop
- Output:
-
kill/killall
kills a specific process by its process id, which you get with the ps command
ps kill ###(the process ID of the process you want to kill)
lscpu
list number of cpus
lscpu
- Output:
-
ps
To display the currently running processes, use the command:
- ps : process status: produces a snapshot of the running processes.
ps
- Output:
-
The output contains a list of the running processes under 4 columns:
- PID: the process identification number
- TTY: the terminal name
- TIME: the running time
- CMD: the name of the command that launches the process
Options that can be used with the ps command:
- ps -a : lists all the running processes of all the users
- ps -u : lists additional information (memory usage, CPU usage percentage, process state code, and process owner)
reboot
sudo reboot
shutdown
sudo shutdown -h now sudo shutdown -h 20:00
-h switch halts processes, and the 20:00 specifies the time for shutdown
top
resource-usage of processes
top
- Output:
-
Note
Unlike the ps command, the top command output updates periodically; You will see real-time updates for running times and CPU usage.
The output of the top command is a shell that allows the user to move through processes and interact with them.
Interacting with a process is done by the keys:
- k : kills the process
- M : sorts the list by memory usage
- N : sorts the list by the process identification numbers
- r : changes the priority of the process
- d : changes the refresh time interval
- c : displays the path of the process