Although it may seem intimidating at first, using command line allows you to quickly perform tasks in a non-cumbersome way.
First navigate to the command line. If you are using a Mac, open Terminal (in Applications in the Utilities folder).
If you are using a windows machine, use Putty or another terminal emulator.
You should see a black window that has a command prompt that looks like this:
Usernames-Macbook-Pro:~ Username$
By typing man before the name of each command, you can get information about how to use them. The manual pages are a set of pages that explain every command available on your system including what they do, the specifics of how you run them and what command line arguments they accept. Some of them are a little hard to get your head around but they are fairly consistent in their structure so once you get the hang of it it’s not too bad.To search for something in the man pages, use / and then type the search term. To proceed to the next instance of the term, use n. To return to the command line, type q.
There are hundreds of different commands you can use to perform a variety of different functions (hold ESC and press the “y” key for a complete list), but here are a few of the most useful.
cd
Executed by itself will bring you to your home directory, while adding a path after cd will bring you to that directory. A directory is basically a folder that holds your files or other directories.
cd ..
Changes directory to one-up the directory hierarchy
ls
Lists the files and directories in the current directory.
ls -a
Lists the files and directories in the current directory including the hidden (dot) files. ls -al will show the files in long form (with their sizes and permissions). However, these sizes are only of the directory itself and do not say how big everything in a directory is. To see this information, use the command ls -shR.
pwd
Returns the path to the current directory
cp file_name path_to_new_directory
Copies a file from you current directory and places in a different directory.
mv file_name path_to_new_directory
Moves the file to a new directory.
cat
Concatenates files to standard output. Prints the contents of the file on the screen. cat file1.txt file2.txt > newfile.txt will concatenate 2 files into a third file.
head -100 filename
Prints the first 100 lines of filename to the terminal.
tail -10 filename
Prints the last 10 lines of filename to the screen.
less filename
Lets you view just a page at a time of a file. After entering this command, the following commands can be used to display a document:
space bar: display the next page,
b: display the previous page,
enter/return: display the next line,
k: display the previous line,
q: quit the viewer
rm
This will remove or delete a file (be careful–cannot undo).
mkdir
Makes a directory. This is what you call folders when you’re in the terminal
rm -rf
Removes a directory and all its contents
control c
Kills the current process
control z
Stops or pauses current process
fg
Resumes last stopped job in the foreground
tab: autocompletes while typing
tab tab: see available autocomplete
ls -ll
Lists the files in a directory as well as their dates and permissions
du -sh
This tells you the disk usage–what is taking up space in a directory
ls directory | wc -l
This lets you count the number of files in a directory
chmod
Change permissions
sed -i -e 's/something/else/g' myfile
This will replace every instance of “something” with “else” in myfile.
echo prints whatever is typed after it. Ex. echo "text" >file.txt prints “echo” to a file called file.txt
exit
Disconnect form Colonial One or current node
Once you feel comfortable with these commands and moving around using the command line, you can create and edit files using a text editor like vim or nano, or log onto Colonial One.
For another great tutorial, visit this site. For more advanced bash commands go here