Ubuntu - Typical Tasks
This articles contains some information about handling a
Ubuntu system.
Table of Contents
- 1. Ubuntu
- 2. Unity
-
- 2.1. Overview
- 2.2. Adding entries to the launcher
- 2.3. Useful shortcuts
- 3. Using the console
-
- 3.1. Editor
- 3.2. Grep
- 3.3. Find files
- 3.4. Calculate the size of a folder
- 3.5. Remove files
- 3.6. Processes
- 3.7. Change owner of files and directories
- 3.8. Create new user via the console
- 4. Environment Variables
-
- 4.1. Add a directory to the path
- 5. Important files
- 6. Package Management
- 7. ShellScript
- 8. Network
-
- 8.1. Network commands
- 8.2. Http debugging with curl
- 8.3. IRC
- 8.4. Ftp
- 9. MySQL
- 10. Apache Tomcat
-
- 10.1. Important Files
- 10.2. Important Commands
- 11. PDF files
-
- 11.1. Command line tool pdftk
- 11.2. Converting .odp file to pdf in batch
- 12. Command line tools for adjusting images
- 13. Connection
-
- 13.1. Telnet / ssh client for Windows
- 13.2. Switch to Console mode from Graphical User Interface
- 14. Tips
-
- 14.1. Shortcut for a shell
- 15. Thank you
Ubuntu Linux is a full fledged Linux system trailed for the
desktop.
Ubuntu builds a unique user interface and offers the users a
solid choice of tools.
Unity is the default windows manager on Ubuntu. It introduced
the
launcher on the left side of Ubuntu and the
Dash
to start
programs.
Press the Windows key to start the Dash. Here you can type in commands to open programs and files.
2.2. Adding entries to the launcher
To add new entries to the launcher you can create an.desktop
file and drag file on the launcher. For example the following creates
an entry to start Eclipse with different shortcuts for different
workspaces.
[Desktop Entry] Icon=application-x-executable Name=eclipse Type=Application Exec=/home/vogella/Eclipse37/eclipse X-Ayatana-Desktop-Shortcuts=Docu;vogella;business [Docu Shortcut Group] Name=Docu Exec=/home/vogella/Eclipse37/eclipse -data /home/vogella/workspace/docu TargetEnvironment=Unity [vogella Shortcut Group] Name=vogella Exec=/home/vogella/Eclipse37/eclipse -data /home/vogella/workspace/vogella TargetEnvironment=Unity [business Shortcut Group] Name=business Exec=/home/vogella/Eclipse37/eclipse -data /home/vogella/workspace/business TargetEnvironment=Unity
The following lists a few useful shortcuts for the Unity window
manager.
Table 1. Window Shortcuts
| Long press on Super (Windows key) | Opens up help for the most common keyboard shortcuts |
|---|---|
| Alt+Left Mouse Click | Allows to moves the current window |
To open a console open the
Dash
and type in
Terminal. Alternatively you can use the shortcut
CTRL+Alt+T.
This will open a window which allow you
to issue commands.
Ubuntu offers several editors which are installed by default.
The most common command line editor is "vim". Start vim from the
command line. vim has two modes, one editing mode and other mode in
which you can move within the file. To
start editing the file use "i".
Once you want to save
press the
escape button and write ":wq". If you
want to exit without
saving use ":q!".
A simple editor with a graphical user interface is gedit.
A simple editor with a graphical user interface is gedit.
Grep is a command line tool to search for
regular expressions.
grep will print the
matching
line to the output and with the --color
flag
you can highlight the
matching strings.
echo "hallo hallo" | grep -P --color "h\w"The following example will search for the number of occurrence of string "abc" in the file "file.txt".
grep -c "abc" file.txt
grep is frequently used together with the find command. For
example the following will case-incentive search for the pattern
".*Legacy.*.xml".
through the content of all files
and list the files
which ends with
".java" and lists these files.
find . -name "*.java" -print0 | xargs -0 grep -i ".*Legacy.*xmi"Use the -r "recursive" option to search a directory and all files included within it.
# Search hello in all files and
# subdirectories of the current directory
grep -r "hello" .
The following demonstrates the usage of the find command.
Table 2.
| Command | Description |
|---|---|
| find dir -name "pattern" 2>/dev/null | Finds recursive all files which apply to the pattern "pattern" starting from the directory "dir". The 2> Send all error messages to the null device. |
| find . -name '*.java' -newer build.xml -print | Search for all java files newer then the file build.xml |
| find . -name '*.java' -mtime +7 -print | Search for all java files newer then 7 dates |
| find . -name '*.java' -mtime +7 -print0 | xargs -0 grep 'swt' | Search for all java files newer then 7 dates using "swt". The -0 options is used for files and folders with spaces. |
The following calculates the size (disk usage))of a folder
"folder1" in
megabyte.
du -sh folder1
Use the command "rm pattern"" to delete files. Be careful with
the usage of files.
# Remove all files which ends with .class in the current directory rm *.class # find all files which ends with .class recursive in all directories below the current one and delete them find . -type f -name "*.class" -exec rm -vf {} \;
To create a new user via the console use the following
commands. This will create the user, set his password and create a
home directory for the user and change this ownership of the
directory.
Careful: This command will allow the user also to execute sudo commands (root).
sudo useradd newuser sudo passwd newuser sudo mkdir /home/newuser sudo chown newuser /home/newuser sudo chgrp newuser /home/newuser
Careful: This command will allow the user also to execute sudo commands (root).
sudo adduser vogella admin
Table 4.
| Command | Description |
|---|---|
| echo $VARIABLE | Prints the content of the environment variable |
| sudo /etc/init.d/tomcat5 start/stop | Start / stops the tomcat server |
| sudo -i | Switches to root |
The
PATH
environment variable is where the system will look for
executable
files. To temporary add the
/home/vogella/bin
directory
to the
PATH
use the following command.
export PATH=$PATH:/home/vogella/binIf you want to add a directory permanently to the path you can edit / create the file
.bashrc
and add the following line to
the
file. Every new directory in the path
must start with
:.
PATH=$PATH:path_to_new_directoryOpen a new shell to make the changes in the
.bashrc
file active.
Table 5.
| File | Description |
|---|---|
| /etc/issue | Contains the Ubuntu version you are running |
| lsb_release -a | Prints out the Ubuntu version you are running |
| /etc/apt/sources.list | Contains the available sources for software installation |
| /usr/share/tomcat | Installation directory for tomcat |
| /var/www/vhosts/domain1 | Contains on my v-server the user directory for a specific domain which is hosted on this server |
6. Package Management
On the command line Ubuntu allows to install / remove and search for packages via the following commands.
Table 6.
| Command | Description |
|---|---|
| sudo apt-get install paketname | Installs a package |
| sudo apt-cache search openjdk | Search for all packages which contain openjdk. The found package can get installed via the "apt-get install" command. |
| aptitude purge | Removes a package and orphaned dependencies and its configuration files |
| aptitude update | Update the local package list |
| aptitude upgrade | Updates any installed packages for which an update is available |
| aptitude clean | Deletes downloaded files which were necessary for installation |
| aptitude show | Show details about a package name |
| aptitude dist-upgrade | Updates the Ubuntu system to the next version |
| dpkg -L packagename | Lists all files and their location in a package |
| sudo updatedb; locate javac | Updates the installation database and locates the javac command. |
To search for the installed packages use the following command.
cat /var/log/dpkg.log | grep "\ install\ "
Shell scripts are short programs that are written in a shell
programming language and interpreted by a shell process in the
console. You can create these programs via a text editor and execute
them in a terminal window.
Create for example the following text file.
Create for example the following text file "yourScript".
Now you can call the shell script via
Create for example the following text file.
chmod 777 yourScript
You also have to make this file executable via:Create for example the following text file "yourScript".
#!/bin/bash
clear
echo "Hello, world."
Now you can call the shell script via
./yourScript. It should print "Hello, world" to the console.
The following commands give you an overview of your network
connections.
curl is a command line tool to issue and receive http (and
other) request. For example if you want to see the HTTP output of a
webpage use the following command.
If you want to the HTTPrequest header (including the HTTP status codes use the following command. This is for example nice to see if your server deliver a 404 return code for your self-defined error page.
curl http://www.vogella.com // Or curl -G http://www.vogella.com
If you want to the HTTPrequest header (including the HTTP status codes use the following command. This is for example nice to see if your server deliver a 404 return code for your self-defined error page.
curl -I http://www.vogella.comYou can set HTTP header information with the -h flag. For example to request a certain MIME type use the -H'Accept:MIME' option.
curl -I http://www.vogella.com -H'Accept:text/plain'To use curl behind a proxy.
curl -x proxy:8080 -G http://www.vogella.com
Tip
curl is also available for Windows. Please see curl for Windows.
For IRC communication you can use the tool xchat. To install it
use "sudo apt-get install xchat".
For a description of MySQL and its installation in Ubuntu see
MySQL - Tutorial
10. Apache Tomcat
Table 8.
| File | Description |
|---|---|
| /usr/share/tomcat5/ | Installation directory of Tomcat |
| psa-webapps | Installation directory for webapps in a vhost environment |
| /usr/share/tomcat5/conf | Configuration Directory for Tomcat |
| /etc/default/tomcat5 | Contains default settings for tomcat. Most important the used java version (jdk). |
| /var/log/tomcat5 | Log files of tomcat |
The "pdftk" command line tool allows to rework existing pdf
files, e.g. extract pages or change the orientation of the pdf file.
You can install it via the following command.
You can install it via the following command.
sudo apt-get install pdftkFor example to extract pages from an pdf document you can use the "cat" option.
# Extract certain pages from a pdf document # "dont_ask" will override existing files without warning pdftk Eclipse4book-20120429.pdf cat 25-27 87-91 95 output Eclipse4-Exercise.pdf dont_ask
ImageMagick allows to convert images in batch see
ImageMagick Command line Options.
For example the following adjusts the DPI size of images to 300.
For example the following adjusts the DPI size of images to 300.
convert -units PixelsPerInch -density 300 input.png output.png
To connect to your Linux system via telnet or via ssh from windows
you can use putty
Putty download page
In case your Linux system is runnig under a graphical user
interface (KDE, Gnome,...) and you need access to the console, use
the Ctrl-Alt-F1 shortcut keys to switch to the first console. To
switch back to Desktop mode, use the Ctrl-Alt-F7 shortcut keys.
Ubuntu 11.10 ships with Unity which has a nice quick starter
menu. To edit this menu you can install the menu manager via:
In the panel click and hold Alt to quick switch/launch apps.
sudo apt-get install alacarteTo open this type "Menu Manager" in the Dash. Choose "programming" in the left panel. Press "New item" button then. Choose name, command, icon
In the panel click and hold Alt to quick switch/launch apps.
For example you can assign the hotkey "Ctrl+Alt+X" to "Open a terminal" via the following entry.
