eg-253:unix7
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+ | ====== UNIX Tutorial Seven ====== | ||
+ | ===== 7.1 Compiling UNIX software packages | ||
+ | |||
+ | Most unix systems have many public domain and occassionally commercial | ||
+ | software packages installed, which are available to all | ||
+ | users. However, you are allowed to download and install small software | ||
+ | packages in your own home directory, software usually only useful to | ||
+ | you personally. | ||
+ | |||
+ | There are a number of steps needed to install the software. | ||
+ | |||
+ | * Locate and download the source code (which is usually compressed) | ||
+ | * Unpack the source code | ||
+ | * Compile the code | ||
+ | * Install the resulting executable | ||
+ | * Set paths to the installation directory | ||
+ | |||
+ | Of the above steps, probably the most difficult is the compilation stage. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ==== Compiling Source Code ==== | ||
+ | |||
+ | All high-level language code must be converted into a form the | ||
+ | computer understands. For example, C language source code is converted | ||
+ | into a lower-level language called assembly language. The assembly | ||
+ | language code made by the previous stage is then converted into object | ||
+ | code which are fragments of code which the computer understands | ||
+ | directly. The final stage in compiling a program involves linking the | ||
+ | object code to code libraries which contain certain built-in | ||
+ | functions. This final stage produces an executable program. | ||
+ | |||
+ | To do all these steps by hand is complicated and beyond the capability | ||
+ | of the ordinary user. A number of utilities and tools have been | ||
+ | developed for programmers and end-users to simplify these steps. | ||
+ | |||
+ | ==== make and the Makefile ==== | ||
+ | |||
+ | The '' | ||
+ | groups of programs. It aids in developing large programs by keeping | ||
+ | track of which portions of the entire program have been changed, | ||
+ | compiling only those parts of the program which have changed since the | ||
+ | last compilation. | ||
+ | |||
+ | The '' | ||
+ | called **Makefile** which resides in the same directory as the source | ||
+ | files. It contains information on how to compile the software, | ||
+ | e.g. the optimization level, whether to include debugging info in the | ||
+ | executable. It also contains information on where to install the | ||
+ | finished compiled binaries (executables), | ||
+ | dependent library files, configuration files, etc. | ||
+ | |||
+ | Some packages require you to edit the **Makefile** by hand to set the | ||
+ | final installation directory and any other parameters. However, many | ||
+ | packages are now being distributed with the GNU '' | ||
+ | |||
+ | ==== configure ==== | ||
+ | |||
+ | As the number of UNIX variants increased, it became harder to write | ||
+ | programs which could run on all variants. Developers frequently did | ||
+ | not have access to every system, and the characteristics of some | ||
+ | systems changed from version to version. The GNU configure and build | ||
+ | system simplifies the building of programs distributed as source | ||
+ | code. All programs are built using a simple, standardised, | ||
+ | process. The program builder need not install any special tools in | ||
+ | order to build the program. | ||
+ | |||
+ | The '' | ||
+ | various system-dependent variables used during compilation. It uses | ||
+ | those values to create a **Makefile** in each directory of the | ||
+ | package. | ||
+ | |||
+ | The simplest way to compile a package is: | ||
+ | |||
+ | - '' | ||
+ | - Type '' | ||
+ | - Type '' | ||
+ | - Optionally, type '' | ||
+ | - Type '' | ||
+ | | ||
+ | |||
+ | The '' | ||
+ | usually use the '' | ||
+ | for a particular configure script. | ||
+ | |||
+ | The only generic options you are likely to use are the '' | ||
+ | and '' | ||
+ | installation directories. | ||
+ | |||
+ | The directory named by the '' | ||
+ | independent files such as documentation, | ||
+ | |||
+ | The directory named by the '' | ||
+ | normally a subdirectory of the '' | ||
+ | machine dependent files such as executables. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ===== 7.2 Installing the development tools ===== | ||
+ | |||
+ | Many Linux distributions will include a set of development tools | ||
+ | (i.e. the '' | ||
+ | Desktop Distribution -- which is designed for non-technical users -- | ||
+ | does not! The development tools have to be installed separately, but | ||
+ | using the '' | ||
+ | |||
+ | You will need to install the **build-essential** package which | ||
+ | includes the C-compiler '' | ||
+ | libraries. To install **build-essential** type | ||
+ | < | ||
+ | |||
+ | Check that the essential tools have been installed as follows: | ||
+ | < | ||
+ | |||
+ | gcc: no input files | ||
+ | |||
+ | ubuntu@ubuntu: | ||
+ | |||
+ | make: *** No targets specified and no makefile found. Stop.</ | ||
+ | Now you are ready to proceed. | ||
+ | |||
+ | <note warning> | ||
+ | settings persistent, you will need to repeat the above procedure | ||
+ | every-time you reboot from the Ubuntu live CD((Of course if you are by | ||
+ | now running from an installed Ubuntu system, your installation will be | ||
+ | permanent)).</ | ||
+ | ===== 7.3 Downloading source code ===== | ||
+ | |||
+ | For this example, we will download a piece of free software that | ||
+ | converts between different units of measurements. | ||
+ | |||
+ | First create a **downloads** directory | ||
+ | < | ||
+ | |||
+ | Then click on this package file {{: | ||
+ | to save it to your new **downloads** directory. | ||
+ | |||
+ | |||
+ | ===== 7.4 Extracting the source code ===== | ||
+ | |||
+ | Go into your **downloads** directory and list the contents. | ||
+ | < | ||
+ | ubuntu@ubuntu: | ||
+ | . .. units-1.85.tar.gz</ | ||
+ | |||
+ | As you can see, the filename ends in '' | ||
+ | |||
+ | First unzip the file using the '' | ||
+ | < | ||
+ | |||
+ | Then extract the contents of the tar file: | ||
+ | < | ||
+ | |||
+ | Again, list the contents of the download directory, then go to the **units-1.85** sub-directory. | ||
+ | |||
+ | < | ||
+ | ubuntu@ubuntu: | ||
+ | |||
+ | < | ||
+ | < | ||
+ | The '' | ||
+ | |||
+ | |||
+ | |||
+ | ===== 7.5 Configuring and creating the Makefile ===== | ||
+ | |||
+ | The first thing you should do is carefully read the **README** and **INSTALL** text files (use the '' | ||
+ | |||
+ | The **units** package uses the GNU configure system to compile the source code. We will need to specify the installation directory, since the default will be the main system area which you will not have write permissions for. We need to create an install directory in your home directory. | ||
+ | |||
+ | < | ||
+ | |||
+ | Then run the '' | ||
+ | < | ||
+ | |||
+ | < | ||
+ | < | ||
+ | to show the contents of this variable. We will learn more about // | ||
+ | |||
+ | If '' | ||
+ | |||
+ | |||
+ | ===== 7.6 Building the package | ||
+ | |||
+ | Now you can go ahead and build the package by running the '' | ||
+ | < | ||
+ | |||
+ | After a minute or two (depending on the speed of the computer), the executables will be created. You can check to see everything compiled successfully by typing | ||
+ | < | ||
+ | |||
+ | If everything is okay, you can now install the package. | ||
+ | < | ||
+ | |||
+ | This will install the files into the **~/ | ||
+ | |||
+ | |||
+ | ===== 7.7 Running the software ===== | ||
+ | |||
+ | Assuming everything worked, you are now ready to run the software: | ||
+ | < | ||
+ | ubuntu@ubuntu: | ||
+ | |||
+ | If you list the contents of the **units185** directory, you will see a number of subdirectories. | ||
+ | |||
+ | | '' | ||
+ | | '' | ||
+ | | '' | ||
+ | | '' | ||
+ | |||
+ | To run the program, change to the **bin** directory and type | ||
+ | |||
+ | < | ||
+ | |||
+ | As an example, convert 6 feet to metres. | ||
+ | |||
+ | < | ||
+ | You want: metres | ||
+ | |||
+ | * 1.8288 </ | ||
+ | |||
+ | If you get the answer 1.8288, congratulations, | ||
+ | |||
+ | To view what units it can convert between, view the data file in the **share** directory (the list is quite comprehensive). | ||
+ | |||
+ | To read the full documentation, | ||
+ | |||
+ | < | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ===== 7.8 Stripping unnecessary code ===== | ||
+ | |||
+ | When a piece of software is being developed, it is useful for the programmer to include debugging information into the resulting executable. This way, if there are problems encountered when running the executable, the programmer can load the executable into a debugging software package and track down any software bugs. | ||
+ | |||
+ | This is useful for the programmer, but unnecessary for the user. We can assume that the package, once finished and available for download has already been tested and debugged. However, when we compiled the software above, debugging information was still compiled into the final executable. Since it is unlikely that we are going to need this debugging information, | ||
+ | |||
+ | What we are going to do is look at the before and after size of the binary file. First change into the **bin** directory of the **units185** installation directory. | ||
+ | |||
+ | < | ||
+ | ubuntu@ubuntu: | ||
+ | |||
+ | As you should see, the file is over 100 kbytes in size. You can get more information on the type of file by using the file command. | ||
+ | |||
+ | < | ||
+ | |||
+ | units: ELF 32-bit LSB executable, Intel 80386, version 1, dynamically linked (uses shared libs), not stripped</ | ||
+ | |||
+ | To strip all the debug and line numbering information out of the binary file, use the '' | ||
+ | |||
+ | < | ||
+ | ubuntu@ubuntu: | ||
+ | |||
+ | As you should see, the file should now be around 36 kbytes -- a third of its original size. Two thirds of the binary file was debug code!!! | ||
+ | |||
+ | Check the file information again. | ||
+ | |||
+ | < | ||
+ | |||
+ | units: ELF 32-bit LSB executable, Intel 80386, version 1, dynamically linked (uses shared libs), stripped</ | ||
+ | |||
+ | Sometimes you can use the '' | ||
+ | |||
+ | |||
+ | ---- | ||
+ | |||
+ | [[eg-253: | ||
+ | |||
+ | --- // |