A B C D E F G H I J K L M N O P Q R S T U V W X Y Z & | ! ; > . \ $
addgroup add new group. See delgroup delete group.
adduser add new user. See deluser delete user.
apt high-level commandline interface for the package management system.
For example, sudo apt install packagename installs new packagename from
repository. Commands sudo apt update and sudo apt upgrade are
necessary for keepering your Ubuntu up to date.
apt-get similar to apt older version.
bash Bourne-Again SHell,
sh-compatible command language interpreter.
.bashrc hidden file in the user accoutn directory,
that initializes an interactive shell session.
bc command line calculator. To exit type quit.
cat concatenate files and print on the standard output.
Read files sequentially and write them to standard output.
cd change directory.
chfn change a user's finger information.
This information is stored in the file /etc/passwd,
and includes the user's real name, work room, work phone number,
and home phone number.
chgrp change group ownership
chmod change modification,
change permissions of files or directories,
chmod [ugoa][[+-=][rwxXstugo] file1][, file2, ...]
chown change user owner.
chsh change shell for the user.
clear clear console screen.
cp copy file or directory; -r recursively.
cp file1 file2 makes a copy of file1 and calls it file2.
CUPTI is a CUDA Profiling Tools Interface (CUPTI), enables the creation of profiling and tracing tools that target CUDA applications.
curl is a command line tool for transferring data with URL syntax.
Command URL (curl) transfers data from or to a server,
using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER,
HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP,
SFTP, SMTP, SMTPS, TELNET and TFTP).
The command is designed to work without user interaction.
curl offers a busload of useful tricks like proxy support,
user authentication, FTP upload, HTTP post, SSL connections, cookies,
file transfer resume, Metalink, and more.
<Ctrl>+<C> interrupts whatever is currently running.
It can get you out of trouble at embarrassing moments.
<Ctrl>+<Q> Resumes current terminal.
Continue a long running program in the terminal.
<Ctrl>+<S> suspends current terminal.
Pause a long running program in the terminal. Stop the job.
Continue job <Ctrl>+<Q>.
<Ctrl>+<Z> puts a foreground process into the background.
delgroup delete group.
deluser delete user.
df disk filesystem. Report file system disk space usage.
dmidecode DMI table decoder. Display hardware information.
For example, sudo dmidecode -t memory displays memory installed.
docker is a computer program that performs operating-system-level
virtualization, also known as "containerization". Docker is used to run
software packages called "containers". Containers are isolated from
each other and bundle their own application, tools, libraries and
configuration files; they can communicate with each other through
well-defined channels. All containers are run by a single operating
system kernel and are thus more lightweight than virtual machines.
dpkg -i similar to apt install (install package),
package manager for Debian.
sudo dpkg -i package.deb
du disk usage. Estimate file space usage.
eb - EasyBuild framework manages software
on High Performance Computing (HPC) systems in an efficient way.
echo display a line of text.
For true ; echo $? the output is 0, for false ; echo $? the output is 1.
emacs powerful Linux editor.
env list all environment variables or run a program in a modified environment.
find dirname -iname file1 search directory dirname and
subdirectories for file file1.
free check memory usage, -m in MBs, -g in GBs.
g++ GNU C++ compiler.
g++ compiler builds the object code from source code,
and it does not generate any intermediate C version of the program.
g++ is a complete compiler, but gcc requires the help of g++.
gcc GNU C compiler.
getfacl get file access control lists (ACL).
Displays the comment header, base ACL (access control list) entries,
and extended ACL entries, if there are any, for each file that is
specified. It also resolves symbolic links.
git version-control system for tracking changes in computer files and
coordinating work on those files among multiple people.
Use Git for savings on https://github.com web-site.
grep globally search a regular expression and print,
search plain-text data sets for lines that match a regular expression.
Same as ed command doing a global search with the regular expression
and printing all matching lines.
gsiscp the same as scp, but for GSI protocol.
gufw is a GUI for ufw, uncomplicated firewall.
gunzip file.txt.gz uncompress file file.txt.gz.
The uncompressed file will be called file.txt.
gzip file.txt compress file.txt.
The compressed file will be called file.txt.gz.
halt power off computer.
Without additional parameter -p user may safely hit the Power button
on his computer manually.
head -30 filename show the first 30 lines.
history 15 list last 15 commands and number them.
hostnamectl query (show) and change the system hostname and related settings.
htop lightweight text-mode interactive process viewer.
iptables is a firewall,
installed by default on all official Ubuntu distributions
(Ubuntu, Kubuntu, Xubuntu). When you install Ubuntu,
iptables is there, but it allows all traffic by default.
Ubuntu comes with ufw --
a program for managing the iptables firewall easily.
ipython or Interactive Python is a command shell for interactive
computing in multiple programming languages, originally developed for the
Python programming language. Command ipython is used for old 2.x version
of Python.
ipython3 new 3.x version of IPython.
jupyter spun-off from IPython in 2014 by Fernando Pérez, project Jupyter
supports execution environments in several dozen languages.
The name is a reference to the three core programming languages supported
by Jupyter, which are Julia, Python and R.
jupyter notebook starts Jupyter in the browser.
kill pid kill (stop) process with the given PID.
killall kill processes by name.
ldconfig configure dynamic linker run-time bindings.
Creates the necessary links and cache (for use by the run-time linker, ld.so)
to the most recent shared libraries found in the directories specified
on the command line, in the file /etc/ld.so.conf,
and in the trusted directories (/usr/lib and /lib).
Command sudo ldconfig restarts /etc/ld.so.conf file and
/etc/ld.so.conf.d/ directory after update.
less similar to more, but allows both forward and backward navigation
through the file.
ln -s target linkname create hard link by default,
or symbolic ("soft") link if the -s (--symbolic) option is specified.
When creating hard links, each TARGET must exist.
Symbolic link mean link to another link, so if remove TARGET file
the data it contained will no longer be accessible with LINKNAME.
link creates only hard links, while ln can create symbolic link.
locate reads through the mlocate.db database file which contains
all file paths in your system.
ls list files and directories.
lsb_release -cs returns the name of your Ubuntu distribution,
such as bionic.
lsb_release -a check Ubuntu version, it gives LSB (Linux Standard Base) and
distribution-specific information on the CLI.
lsmod show which loadable kernel modules are currently loaded.
make clean && make clean previous compilation recompile automatically
large program.
man retrieve the information in the manual and
display it as text output on the screen.
If unsure which manual item to read, use a keyword search
man -k keyword | more.
mc call Midnight Commander file manager.
mkdir -p dirname1/dirname2 make new directory.
module - command interface to the Modules package.
more view (but not modify) the contents of a text file one screen at a time.
less is a similar command with the extended capability of allowing both
forward and backward navigation through the file.
mv file1 file2 move (rename) file1 to file2.
nano file.txt small and friendly text editor.
When Midnight Commander is opened <Ctrl>+<O> keystoke doesn't save,
but switch to MC.
npm node.js javascript package manager.
nvcc NVIDIA's CUDA Compiler,
it hides the intricate details of CUDA compilation from developers.
nvidia-smi check NVIDIA driver version.
passwd change user password.
pip package manager
used to install and manage software packages written in Python 2.x.
pip3 package manager for Python 3.x.
pipenv automatically creates and manages a virtualenv,
as well as package manager.
While pip can install Python packages, pipenv is recommended as
it’s a higher-level tool that simplifies dependency management for
common use cases.
printenv print all or part of environment.
ps list of user processes (programs) that are running,
along with their process ID (PID).
Report a snapshot of the current processes.
pwd print working directory, show current directory.
pycharm-community & is python IDE for professional developers
by JetBrains company.
python programming language, high-level and general-purpose.
Command python is used for old 2.x version, use python3 instead
for new 3.x version.
python3 new 3.x version of Python programming language.
reboot reboot computer.
rm remove file or directory.
rmdir dirname remove directory.
Option -r recursively removes directory and subdirectories.
rsync is a fast, versatile, remote (and local) file-copying tool.
Its basic command syntax is similar to scp.
sbatch - Submit a batch script to Slurm.
setfacl set file access control lists (ACL).
Sets (replaces), modifies, or removes the access control list (ACL).
It also updates and deletes ACL entries for each file and directory
that was specified by path.
scp file user@machine: secure copy file to the home directory
of user on machine. Note the colon!
sftp machine interactive secure FTP
(file transfer protocol) with machine.
sh standard command language interpreter.
srun - Run a parallel job on cluster managed by Slurm.
If necessary, srun will first create a resource allocation
in which to run the parallel job.
ssh connection via SSH protocol.
ssh user@machine -p 22 login securely as user into machine
via port 22.
shutdown -h now power off computer immediately. The same as halt -p
and poweroff.
Additionally it send an ACPI command to signal the power supply unit to
disconnect the main power. This prevents you from having to physically
push the Power button on your computer.
sleep suspend program execution for a specified time.
For example, sleep 3600 && systemctl suspend processname
auto sleep after one hour.
snap tool to interact with snaps.
Snaps are packages that are mainly designed to be sandboxed and isolated
from other system software, secure, and easily installable, upgradeable,
degradable, and removable irrespective of its underlying system.
snapd is the service which runs on your machine and keeps track of your
installed snaps, interacts with the store and provides the snap command
for you to interact with it.
sort filename sort strings from file.
ls | sort sort files in directory.
su username login as another user. Check login with whoami command.
To run just a single command as another user
sudo -u username command
sudo from "superuser do" execute a command
as another user, superuser by default, similar to su
systemctl introspect and control the state of the systemd system
and Service Manager. Show status of the system systemctl status.
systemd system and service manager.
tail -25 filename show the last 25 lines.
tail -f filename show the last few lines and keep updating
as the file grows.
tar xvzf file.tar.gz un-gzip and un-tar *.tar.gz file.
tee read from standard input and write to standard output and files.
top show the top few processes sorted according to CPU usage.
Once top is running, type <M> to sort by memory usage,
and <Q> to quit.
touch change file timestamps and / or create file touch file.txt.
tty print the file name of the terminal connected to standard input.
tty command shows the device node of the terminal in which it is running
or prints "not a tty" if it is not running inside a terminal.
Ubuntu is a Linux operating system.
ufw uncomplicated firewall.
The default firewall configuration tool for Ubuntu is ufw.
Developed to ease iptables firewall configuration,
ufw provides a user friendly way to create an IPv4 or IPv6
host-based firewall. By default ufw is disabled.
gufw is a GUI that is available as a frontend.
umask return or set the value of the system's file mode creation mask.
For the root user default is umask 022, so any new files will,
by default, have the permissions 644 (666 - 022).
Likewise, any new directories will, by default,
be created with the permissions 755 (777 - 022).
umask is inverse of chmod.
uname print certain system information like kernel name, hostname,
operating system, etc.
unzip file.zip -d destination_folder un-zip *.zip file.
usermod modify a user account.
Modify or change any attributes of a already created user account
via command line.
sudo usermod -a -G groupname username add user username
to the group groupname.
--version option print information about program version and then exit.
vim clone of vi screen-oriented text editor.
virtualenv tool to create isolated Python environments.
visudo edits the sudoers file in a safe fashion, analogous to vipw.
visudo locks the sudoers file against multiple simultaneous edits,
provides basic sanity checks, and checks for parse errors.
If the sudoers file is currently being edited you will receive a message
to try again later.
vmstat -s show memory usage statistics.
wc filename counts lines, words and characters in a file.
which identify the location of executables (which command).
who show who is logged in on the system.
whoami print current user ID.
wget retrieve content from web servers. Download via HTTP, FTP, etc.
xargs build and execute command lines from standard input.
command & run command in background.
command &> /dev/null run command in background without output on console.
command &> ~/Documents/output.log run command in background and
re-write, create new output.log file
which is in the $HOME/Documents directory.
command &>> ~/Documents/output.log run command in background and
write, append output to the end of the file output.log
which is in the $HOME/Documents directory.
command1 && command2 logical AND, run command2 only
if command1 has no errors (zero exit code echo $?).
command1 | command2 is a pipeline, which sends output of the
command1 to the input of the command2.
command1 || command2 logical OR, run command2 only
if command1 has error (non-zero exit code echo $?).
command1 ; command2 separator between two commands.
!! repeat your last Unix command. See history command.
!42 repeat command numbered 42.
!wh repeat the last command beginning with "wh".
!!addtext appends "addtext" to previous command line.
^string1^string2 substitute string2 for string1
in previous command.
command > output.log create or re-write output.log file
with command output, previous info of the file will be lost.
command >> output.log create or append to the end of output.log file
command output, previous info of the file will remain.
command < input.log takes input for command from input.log.
. current directory.
For example, ls . lists files in the current directory.
.. parent directory.
For example, ls .. lists files in the parent directory.
./command run the command in the local directory.
~ home directory, equivalent to $HOME.
For example, ls ~ lists $HOME directory.
command1 ;\
command2 backslash ignores next symbol like new line or
executes special action sign like \a bell or \t tab.
$HOME similar to ~ contains path to your home directory.
$LD_LIBRARY_PATH environment variable tells the shell which directories
to search for general libraries.
Since Ubuntu 9.04, LD_LIBRARY_PATH cannot be set in $HOME/.profile,
/etc/profile, nor /etc/environment files. You must use
/etc/ld.so.conf.d/.conf configuration files instead.
$PATH environment variable is a colon-delimited list of directories
that your shell searches through when you enter a command.
echo $PATH to find out what your path is.