This page lists commonly used Linux commands to help those who are not very familiar with Linux command environment. I have been collecting and recording those from my experience.
I was once a beginner, so I can understand the pain for Linux beginners. I have not yet seen any post that has done comprehensive collection of commands on Linux, so I thought I could help this out. That is why you see this post. Here you go. Happy Learning!
You can see further reading list at the end of this post.
Note: Do not contain space in your filename or directory name, use underscore instead of space.
======Basic commands:
this command will goes back to the home directory of your account, no matter where your current directory is located in your terminal.
this command will go to the parent directory of your current directory in terminal
remove/delete an empty folder.
example:
first cd into the parent folder of the empty folder to remove
rmdir test
- rm -rf ./*
first cd to a directory, and this command will empty all of things under the current directory
list all the files and folders under current path
list all the files and folders with details like dates.
list files and folders ordered by time.
list all the csv files under the current directory in long format by time and in reverse order, the file size in human readable format (e.g., in mb, or gb, instead of byte size)
-l List in long format. If the output is to a terminal, a total sum for all the file sizes is output on a line before the long listing.-r Reverse the order of the sort to get reverse lexicographical order or the oldest entries first (or largest files last, if combined with sort by size.-t Sort by time modified (most recently modified first) before sorting the operands by lexicographical order.
list all the csv files under the current directory in long format by time and in reverse order, the file size in human readable format (e.g., in mb, or gb, instead of byte size)
find -name ‘*.jpg’ -exec cp {} ./test/ \;
Find all jpg files and then copy the found files to the folder test which is subfolder of current path.
Note that: the current path should be the path where the files to search are located. (i.e., use cd to locate to the directory where the files are in before type in the cmd below into terminal.)
-r means recursive, it will remove folders and subfolders and files within the folders and subfolders
-f means force
create new folder
example:
mkdir image
cp [filename] [new filename]
copy and rename file
cp [filename] [path/to/new/lotcation/filename]
copy the file to another location
if you use this commond to copy a directory, you would meet this error:
cp: omitting directory ...
The error notice means you told cp to copy files and not directories. The warning is about cp finding a directory and informing you it will be skipped.
cp -r [directory] [path/to/new/location/directory]
copy a directory to another location.
cp -r means recursive and this option will make cp also include sub-directories.
If you meet permission denied error, add sudo before the command, and it will ask your password.
- mv
[directory] [path/to/new/location/directory]
If you meet permission denied error, add sudo before the command, and it will ask your password.
- nano [new file name or /path/to/new file/new file name]
example:
nano myexample #it will create a new empty file named “myexample” under the current directory
If the file name already exists, it will open the file and you can edit it.
Note: Ctrl+O to save the file, and then hit Enter, and then Ctrl +X to close the file.
======More advanced commands:
- cd into directory without having permission
When cd into a directory and the following error occurs
bash: cd: your-dirctory: Permission denied
The solution is:
Enter super user mode, and cd into the directory that you are not permissioned to go into. Sudo requires administrator password.
sudo su
cd directory # you will notice that your prompt changes after your enter your root password. now you can cd to the directory.
# to exit "super user" mode, type exit.
check GPU information on Ubuntu
look for “VGA compatible controller:”…
check GPU info and GPU usage.
reboot a server from terminal
shut down a server from terminal
Note: If your Ubuntu Server 16.o4 LTS has Black Screen after reboot or shut down, try pressing (simultaneously) Ctrl + Alt + F2 to see whether you can switch to different console
This is a vncserver command. It is used to kill a port of a GUI by VNC server, where 1 is the port you would like to kill.
- vncviewer -via username@yourserver_hostname :1
connect to a server via vncviewer from a linux-based client. you need to change the port number 1 to yours.
echo is a built-in command in the bash and C shells that writes its arguments to standard output.
See here, and here, and herefor example usage of it.
See here for example usage of cat command.
see here for example usage of chmod command.
- check supercomputing Cluster’s Linux distribution and version
$ lsb_release -a
LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: RedHatEnterpriseServer
Description: Red Hat Enterprise Linux Server release 6.4 (Santiago)
Release: 6.4
Codename: Santiago
- show the list of top processes ordered by RAM and CPU use in descendant form
(remove the pipeline and head if you want to see the full list):
$ ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head
Brief explanation of the options used in the command above:
— The -o (or –format) option of ps allows us to specify the output format.
— the processes’ PIDs (pid), PPIDs (pid)
— the name of the executable file associated with the process (cmd), and
— the RAM and CPU utilization (%mem and %cpu, respectively).
We can use --sort to sort by either %mem or %cpu. By default, the output will be sorted in ascendant form, but usually we prefer to reverse that order by adding a minus sign in front of the sort criteria to make it list in descendant.
To add other fields to the output, or change the sort criteria, refer to the OUTPUT FORMAT CONTROL section in the man page of ps command.
======File Transfer: getting files to/from your account on a server
- On Linux generally the command line scp command.
Examples of using the command line are:
scp -p file_name username@yourserver_hostname:destination/directory
- or for a full directory tree:
scp -pr dir_name username@yourserver_hostname:destination/directory
Note that if you want to transfer files from server to your client computer, just reverse the directory.
e.g., scp -pr username@yourserver_hostname:source/directory dir_name_on_your_client
======download files
- wget (tool for downloading files) (pdf)
- See Linux wget command (pdf), which provides detailed and comprehensive different tags (options) to use with wget command.
======Save terminal output to a file
sudo command -option | tee logThis command will show output on terminal and save to a file at the same time.- Save terminal output to a fileredirect the output to a file:
someCommand > someFile.txt Or if you want to append data: someCommand >> someFile.txt If you want stderr too use this: someCommand &> someFile.txt or this to append: someCommand &>> someFile.txt
- Tail -f log.txt
Python related commands:
type python in terminal, and it will show python 2.7 version info and also enter into python 2 environment
- enter python 3 environment
python3
and it will show python 3 version info (e.g., python 3.5.2) and also enter into python 3 environment.
======Git related commands
- git clone the url to gitclone
for example:
first cd into the folder you want the models to be cloned to in your terminal, and then issue this command. it will clone the model foder from https://github.com/tensorflow/models under your current folder in your terminal.
git clone https://github.com/tensorflow/models
======Some useful shortcuts on linux
- you can open multiple terminals
open each terminal by pressing Ctrl + Alt + T.
- Shortcut to bring all open terminals to the front
After you bring one terminal window in the front, press Alt+~ to bring all other terminal windows in the front one by one:
- CTRL + C − terminate the current command.
======References and further reading list:
Linux and Unix top 10 command pages (See here for links to more commands intro)
Below is a listing of the top 10 Unix command pages by the amount of times they have been accessed on the Computer Hope server.
- Linux and Unix tar command help
- Linux and Unix chmod command help
- Linux and Unix ls command help
- Linux and Unix find command help
- Information about the Linux and Unix grep command
- Linux and Unix cp command help
- Linux and Unix vi command help
- Linux and Unix ifconfig command help
- Linux and Unix date command help
- Linux and Unix kill command help
======TOC of the nice tutorial: Linux Shell Commands: A Tutorial Quick Reference for Desktop Users
Table of Contents
1. A Short Intro to the Command Line
This chapter will acquaint you with the basics of the command line. To maximize your learning, you should follow along by typing in the example commands given. Every major Linux distribution has a menu item called “shell”, “console”, “terminal” or the like, which will give you a window with a command line interface. In this book, I assume that readers work in a graphical desktop environment and use the Bash shell in a terminal window. Bash is the default shell in all major Linux distributions.
2. Getting Information
The commands presented in this chapter provide valuable information on the state and configuration of your system.
3. Managing Files and Directories
The command line offers you great flexibility in creating, copying, moving and editing files and directories, as this chapter shows.
4. Managing Processes
Linux provides powerful tools for controlling the execution of your programs. Some of the most important tools are presented in this chapter.
5. Working with Text
Processing plain text files is a big strength of Linux. The commands presented in this chapter allow you to display particular parts of files (e.g. head, tail), reorder their contents (e.g. sort), carry out search/replace operations (e.g. grep, sed), and much more.
- cat (concatenate and output files) (pdf)
- cut (output columns from files) (pdf)
- diff (show differences between files) (pdf)
- grep (print lines matching a pattern) (pdf)
- head (output the first part of files) (pdf)
- less (view file by pages) (pdf)
- pdftk (manipulate PDF files) (pdf)
- sed (search and replace text) (pdf)
- sort (sort lines of text files) (pdf)
- tail (output the last part of files) (pdf)
- wc (count lines, words and characters) (pdf)
6. Being Productive
This chapter collects some commands that can help you accomplish everyday tasks quickly and efficiently. Many of the commands are faster or more reliable replacements for popular graphical applications. For example, wget can replace a graphical download manager.
======The end of the TOC of the nice tutorial: Linux Shell Commands: A Tutorial Quick Reference for Desktop Users
======apt-get usages
======curl command examples
cURL can be used in many different and useful ways. Using cURL, we can download, upload and manage files, check email address, or even update status on some of the social media websites or check the weather outside.
cURL is very useful command line tool to transfer data from / to a server. cURL supports various protocols, including FILE, HTTP, HTTPS, IMAP, IMAPS, LDAP, DICT, LDAPS, TELNET, FTP, FTPS, GOPHER, RTMP, RTSP, SCP, SFTP, POP3, POP3S, SMB, SMBS, SMTP, SMTPS, and TFTP.
This tutorial covers five of the most useful and basic uses of cURL tool:
–Check URL
One of the most common and simplest uses of cURL is typing the command itself, followed by the URL you want to check
curl https://example.com
#This command will display the content of the URL on your terminal
–Save the output of the URL to a file
The output of the cURL command can be easily saved to a file by adding the -o option to the command, as shown below
curl -o website https://example.com
#the output will be save to a file named ‘website’ in the current working directory
–Download files with cURL
curl -O https://example.com/file.zip
# the -O option used for saving files to current working directory without renaming
# e.g., the ‘file.zip’ zip archive will be downloaded to the current working directory.
curl -o archive.zip https://domain.com/file.zip
# the ‘file.zip’ archive will be downloaded and saved as ‘archive.zip’.
curl -O https://domain.com/file.zip -O https://domain.com/file2.zip
# cURL can be also used to download multiple files simultaneously
#cURL can be also used to download files securely via SSH
curl -u user sftp://server.domain.com/path/to/file
# Note that the full path of the file to be downloaded is required
–Get HTTP header information from a website
You can easily get HTTP header information from any website you want by adding the -I option (capital ‘i’) to cURL.
curl -I http://example.com
–Access an FTP server
# access your FTP server with cURL
curl ftp://ftp.domain.com --user username:password
# cURL will connect to the FTP server and list all files and directories in user’s home directory
curl ftp://ftp.domain.com/file.zip --user username:password
# download a file via FTP using curl
curl -T file.zip ftp://ftp.domain.com/ --user username:password
# upload a file to the FTP server
–check cURL manual page to see all available cURL options and functionalities
man curl
This post covers detailed and comprehensive explanation of different options to use with curl command.
Linux has the habit of caching lots of things for faster performance, so that memory can be freed and used if needed.
- $ cat /proc/meminfo
- $ vmstat -s
