How to use the Ubuntu Linux Terminal on your Dell Computer

The man command displays the manual for any command that is used in the Terminal.

Most shell commands accept various options. To get some information about a command and a list of the available options, use the man - short for manual command. Give the name of the command that you want to find more about as its argument. That is which command the man command works on.

Example: If you enter the command man who, the following output is displayed.

 WHO(1)                     User Commands                     WHO(1)

 NAME
    who - show who is logged on

 SYNOPSIS
    who [OPTION}... [ FILE | ARG1 ARG2 ]

 DESCRIPTION
    -a, --all
       same as -b -d --login -p -r -t -T -u

    -b, --boot
       time of last system boot

    -d, --dead
       print dead processes

    -H, --heading
       print line of column headings

    -i, --idle
       add idle time as HOURS:MINUTES, . or old (deprecated, use -u)

    -l, --login
       print system login processes

    --lookup
       attempt to canonicalize hostnames via DNS

    -m, only hostname and user associated with stdin

 Manual page who(1) line 1

Many of the manuals are several screens long. Use the cursor or ARROW keys or the Page Up and Page Down keys to navigate through the text. The spacebar key shows the next line of text. Pressing the q key quits the manual and returns to the shell.

We can see from the man page that we can use the -a option to display more information about the active user sessions.

      user@3[user]$ who -a
   

    user@3[user]$

It also reads help files for programs, the man command can also give information about shells, functions, and libraries.

If you are not sure how to use a specific command, run the command with the -h or –help switches. You see usage information and a list of options that you can use with the command.

Example: If you want to know how to use the wget command, type wget –help or wget -h.

      User@Ubuntu@#$ wget --help
 GNU Wget 1.12, a non-interactive network retriever.
 Usage: wget [OPTION]... [URL]...

 Mandatory arguments to long options are mandatory for short options t
 oo.

 Startup:
  -V, --version display the version of Wget and exit.
  -h, --help print this help.
  -b, --background go to background after startup.
  -e, --execute=COMMAND execute a '.wgetrc' -style command.

 Logging and input file:

This often prints a lot of information to the terminal. It can be unwieldy to scroll through. To read the output more easily, you can pipe it through the less command. Which allows you to scroll through it with the cursor or ARROW keys on your keyboard.

Example: wget -help | less

 GNU Wget 1.12, a non-interactive network retriever.
 Usage: wget [OPTION]... [URL]...

 Mandatory arguments to long options are mandatory for short options t
 oo.

 Startup:
  -V, --version display the version of Wget and exit.
  -h, --help print this help.
  -b, --background go to background after startup.
  -e, --execute=COMMAND execute a '.wgetrc' -style command.

 Logging and input file:
  -o, --output-file=FILE log messages to FILE.
 :

Press q to close the less utility when you are done.

To find a specific option, you can pipe the output through the grep command. (For example: Use the following command to search for options that contain the word proxy.)

wget -help | grep proxy

  User@ubuntu:~$ wget --help | grep proxy
  --no-proxy explicitly turn off proxy.
  --proxy-user=USER set USER as proxy username.
  --proxy-password=PASS set PASS as proxy password.
  User@Ubuntu:~$

Some commands are also documented inside the info system. The information here complements what the man command displays.

Example: Enter the command info ls, the following output is displayed.

   [support@support]$" info ls

You can now view a manual with important information about the ls command.

   File: coreutils.info, Node: ls invocation, Next: dir invocation, Up: Directory listing

  'ls': List directory contents
  =============================

   The 'ls' program lists information about files (of any type,
  including directories). Options and file arguments can be intermixed
  arbitrarily, as usual.

    For non-option command-line arguments that are directories, by
  default 'ls' lists the contents of directories, not recursively, and
  omitting files with name beginning with '.'. For other non-option
  arguments, be default 'ls' lists just the file name. If no non-option
  argument is specified, 'ls' operates on the current directory, acting
  as if it had been invoked with a single argument of '.'.

   By default, the output is sorted alphabetically, according to the
  locale settings in effect. (1) If standard output is a terminal, the
  output is in columns (sorted vertically) and control characters are
  output as question marks; otherwise, the output is listed one per line
  and control characters are output as-is.
  --zz-Info: (coreutils.info.gz)ls invocation, 48 lines --Top------------------
  Welcome to info version 4.3 Type C-h for help, m for menu item.

You can scroll down the page by pressing the spacebar key or by using the cursor/ARROW keys.

• For help, press H
• To quit, press Q
• To search for a menu item, press M

1. cd - Moves you back to your home, same as cd ~

2. cd.. - Takes you back one directory. Starting in /home/user/Desktop, cd.. puts you into /home/user. This can be expanded to cd ../../ which moves you back two directories to /home.

3. cd foldername/ - Move you forward to the given folder in your current folder.

4. cd /some/other/path - Takes you to the specified folder path. If you got the path right. Do not forget you can use the TAB key to autocomplete.

1. ls - Lists all your files in the current folder.

2. ls -l - Provides a longer list including owners, permissions, size, and date modified.

3. ls -a - Displays the hidden files and folders and the normal list.

4. ls -al - Combines two options to display both the hidden files and folders and do it in the long format.

5. ls -h - Shows file sizes in human readable format KB, MB, GB, file sizes instead of bytes. It is most often used with the -l flag.

6. You can view files in directories you are not even in. If I am in /home/user/Desktop and I want to view a file in /home/user, I can do ls ../ which lists the files one directory back.

1. cp file /path/to/folder - Copies the specified file to the given path.

2. cp -r folder /path/to/folder - Copies repeatedly the contents of the folder to another folder.

3. cp *.extension /path/to/folder - Copies the files matching the given extension to the new folder. To copy all .doc files, it becomes cp *.doc /path/to/folder and the folder must exist.

4. cp name* /path/to/folder - Copies all the files starting with name to the given folder. To copy all files starting with example, it becomes cp example* /path/to/folder and the folder must already exist.

1. The syntax of mv is similar to the example above with cp exempt for example #2. mv does not take the -r flag since moving a folder also moves its contents. The syntax is not exact in all instances, but works with the above examples. Consult your manpages for more details.

1. Removing files using rm is permanent. It does not use the Trash bin. Use this with caution and ensure that you are deleting exactly what you want, before you press the Enter key. If you overcomplicate your delete commands, it never ends well.

2. rm file - Remove that specific file from the computer.

3. rm -r folder - Remove that specific folder from the computer.

4. rm -rf folder - Removes that specific folder forcefully from the computer. This command can mess up your configuration if it is used incorrectly.

1. You can edit files using nano in a terminal to do quick and rough files all the way up to full configurations. It can be useful, but it handles plain text files and programming files, so things like Microsoft Word documents do not open properly.

2. If the root owns a file, a regular user cannot edit it. nano must be prefixed with sudo; in order to save changes. It opens in read-only mode otherwise.

3. nano newfile.whatever of the specified name and opens it for editing.

4. nano existing_file - opens the existing file for editing.

5. From inside nano

6. Save the file by pressing the CTRL+O keys together and either change the name or press the Enter key to keep the same name. This saves the file.

7. Exit nano by using the CTRL+X keys together. If you have unsaved changes, then it asks if you want to save them.

1. mkdir folder_name - Creates the folder with the specified name

2. mkdir -p /path/to/folder/name - Creates each folder as necessary. To create a folder /home/user/1stfolder/2ndfolder, and only /home/user exists, using mkdir -p makes both directories 1stfolder, and 2ndfolder.

1. ps aux - Lists all the processes in detail running on the computer. This includes user, Process ID PID, and name of the process. Using this you can view the process list and if necessary you can kill unnecessary or stalled processes.

1. kill PID - PID is a number referencing the offending process. You should obtain the PID from a command like ps aux. If a process refuses to die, you can also specify kill -9 PID which should terminate the process by any means.

2. killall program - Killall kills by name all instances of the listed program. If there are for example 3 Firefox Internet browser sessions open, killall Firefox does exactly that, kill all Firefox sessions. kill would take the specified PID of the offending Firefox process that you want to kill and kill that one only.

3. xkill is a user interface way to click and kill windows. Typing in xkill should bring up a skull-and-crossbones icon and the next window clicked is killed.

1. Pipes are shown as a straight bar, otherwise known as the | key.

2. It is a rarely used key in Windows, but it is often found on the backslash key.

3. These are used to link commands together. Pipes take the output of one command and route it to be used as input for a second command when they are chained together.

4. Consult online resources for more information about pipes and their use as there are volumes that are written on them.

1. > is used to overwrite the existing files contents by replacing them with the output from the new command.

2. >> is used to append information to the existing files. This is useful for logging actions.

3. Example: ps aux > processes.log sends the output of ps aux to the file processes.log for viewing the command output in a text editor and overwrites the current contents of the file.

1. tee is used along with a | in order to take the command output and send it somewhere else. This is useful if there are errors which you miss. This way whatever goes on the screen is also captured to a file.

2. Example: dmesg| tee boot.txt would run the command dmesg which shows the initial boot info. The | sends the output of dmesg to tee, which then does its job by sending it to the terminal and to the log file boot.txt.

1. Do you want to run a file in the current directory after it is marked executable? The ./ operator can run the file as a normal user provided you do not need root rights. ./ literally means in the current directory so it does not work on files outside of the present directory.

2. If you want to run a file not in the current directory, then you must pass the path to the proper running program. If it is a python program, it is python /path/to/file and if it is a shell file, it is sh /path/to/file as an example. There are other programs, but these are the most common.

3. If you want to run a file with root rights because you received operation not permitted?. You must prefix the command with sudo. As with the above example, sudo python /path/to/file runs the script with root rights.

4. If you want to run a user interface program from the terminal, then type the program name - case sensitive! and it launches. This renders the current terminal unusable. Closing the terminal while the program is open kills the program as well. A better way is to background the program, using program_name and then typing the word exit at the terminal to close it and keep the process running.

5. If you want to run a user interface program with root rights from the terminal, then prefix it with gksudo or gksu and not sudo. Using sudo to launch user interface applications is a bad habit and should be avoided.

6. Do not use sudo only because something brings up Operation not permitted. Keep in mind that you can destroy computers by running commands in the wrong place with root rights. Ensure that your files come from reputable sources.