Multiple Lazarus

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Multiple Lazarus instances

You can have one directory with Lazarus in it on your system or more. These directories can contain the same or different versions of Lazarus and can be made to work independent of each other (see the section dealing with --primary-config-dir below). Because you don't have to install Lazarus and the versions may be the same, the concept of having more than one Lazarus directory on your system will be called "multiple instances" in this article.
Runthrough for Linux at DualLaz.


  • Make Backups of
    • Your primary config (e.g. ~/.lazarus under Unix)
    • Your projects *.lpi and *.lps

Who needs multiple Lazarus instances and who does not?

You need multiple Lazarus instances...

  • to have several versions of Lazarus
  • to have one Lazarus version compiled with several different versions of FPC

You don't need multiple instances...

The Lazarus directory

The Lazarus directory (i.e. the directory where the Lazarus application is) is overridable using --lazarusdir, this is useful when running Lazarus from e.g. USB sticks with varying mountpoints or driveletters.

The config directory

All IDE options for an instance are saved to a config directory. Under Linux, macOS and BSD the default config directory is ~/.lazarus. Note the beginning dot, which makes it a hidden directory.

On Windows, settings are saved to the User AppData folder, which maps to a different directory depending on the Windows version (and language, in Windows XP and earlier). See also information here: Windows. Note that you won't see the configuration directory in Windows unless you select to see hidden and system files. To view the directory, type:


in the Start/Run box or in the address bar of Windows Explorer, which should bring you to the Local Application Data directory. For default installs, the settings are stored in the Lazarus directory shown there.

Operating System Default location for the config directory Remarks
Linux, macOS, BSD, other UNIXes ~/.lazarus Hidden directory
Windows XP C:\Documents and Settings\<User name>\Local Settings\Application Data\lazarus English Windows; others may have different paths
Windows Vista and higher C:\Users\<User name>\AppData\Local\lazarus\ Regardless of selected language

The config directory can not be shared between different Lazarus versions. A newer Lazarus can read older configs and will update them automatically. There is no guarantee that an older version can read config files of a newer version. It is always a good idea to make a backup of your configs from time to time for time you might’ve change something weird and not know what it was.

Solution for separating instances using multiple config dirs

The config directory can be given on the command line with the --primary-config-path parameter (shorter version: --pcp). For example:

lazarus --primary-config-path=~/.lazarus2

will start an IDE using ~/.lazarus2 as config directory. This way you can have an arbitrary number of config directories and start several independent Lazarus instances. As Lazarus creates the settings files from default if they don't exist, you can specify empty directories if you want.

If you use this often, then a small shell script can be created:

/path/to/lazarus --primary-config-path=~/.lazarus2

In Windows you cannot use ~ so use instead, for example, a shortcut on the desktop with the following parameters to call Lazarus:

\path\to\lazarus.exe --primary-config-path=lazarusconf

This will place the lazarus configuration directory inside the lazarus directory.

Using lazarus.cfg file

Another way for setting config directory is using a “lazarus.cfg" file and putting it into the folder with the Lazarus executable and putting this line into it :


You can make a config folder any where you like and set it's path to the cfg file. After that Lazarus will use this lazarus.cfg file and there is no need to make a shell script or use shortcut file with the —-pcp parameter.

For example, for a Windows installation it will be like this : A config folder and a lazarus.cfg file near the Lazarus executable and put a value like this for example into the cfg file :


And run Lazarus. It will ask for some config values and after that you can make a simple shortcut for later use without any parameters.

Config directory files

See the Primary Config Path page.

lazarus.dci - stores the Lazarus Code Templates

editoroptions.xml - information about colors, fonts and other editor options

miscellaneousoptions.xml - packages information

environmentoptions.xml - stores the history of opened projects and files (Recent Opened Files and Projects)

The Lazarus files

The Lazarus source archive is contained in a single directory. You can simply compile Lazarus (eg, for Linux or for Windows ) and a lot of files and subdirectories will be created, but and all will be below that single subdirectory.

A Lazarus instance (sources and resources) is a single subdirectory. Just copy this directory and you get a whole new Lazarus instance.

You don't need to install Lazarus to be able to run it. But if you do indeed install Lazarus, you get some nice shortcuts on your desktop and some file types (e.g. lpk, lpi, pas) are associated with that Lazarus installation. These things are platform dependent. You can have only one formally installed Lazarus but secondary installs work just as well, typically you will start the one you want with a script or cd-ing to its own directory and starting it there. A formal install is typically added to your PATH so care might be needed, when using a secondary copy, that you don't get the 'on path' executable, some users prefer to have no formally installed copies for that reason, Lazarus, built from source works fine from its source directory.

Newer installers support installing Lazarus multiple times. Alternatively, You can also add another Lazarus instance manually quite easily. Of course, file associations etc. can only be linked to one single Lazarus instance.


See the instructions for Installing Lazarus from Source and repeat that as many times, each in a new directory, as you like. It often makes sense to use your distro provided version of FPC (as long as its up to date) and build your Lazarus from source. Don't bother to "install" Lazarus, its fine to just have it all in your own file space, cd into the desired directory and launch lazarus from the command line. Just make sure each Lazarus directory has its own config directory (and knows how to find it).

If you do decide to have one or more Lazarus "installs", its a good idea not to have a package installed version as well. They tend to cause some PATH confusion.

Find a 2015 run-through for Linux 64 bit at DualLaz.

Example 1 : A normally installed Lazarus instance plus the git version

Download and install the Lazarus debian- & .rpm - packages as normal.

Then download the Lazarus git archive to a directory of your choice, preferably somewhere in your home directory (e.g. ~/lazarus). See here Getting Lazarus from the GitLab server.

Start your secondary Lazarus with:

/home/you/lazarus/startlazarus --pcp=~/.lazarus2nd

Example 2 : A normally installed Lazarus instance plus a manual copy

i.e. you obtain two subdirectories:

/usr/lib/lazarus     original  copy     via debian install
/home/you/lazarus    secondary copy 

or you may look at:

/home/you/development/lazarus    original copy      via fpcUP install
/home/you/lazarus                secondary copy 

Download and install the Lazarus debian-packages as usual.

Then copy the Lazarus directory to your home directory and change the ownership of the files:

cp -a /usr/lib/lazarus $(HOME)/
chown $USER:$USER -R $(HOME)/lazarus

(Note: The chown line assumes that your group has the same name as your username. If not, replace $USER:$USER with your username:groupname)

Now change your Lazarus desktop/menu shortcut to start the secondary copy

/home/you/lazarus/startlazarus --pcp=~/.lazarus2nd

Then start the IDE and change the environment options: Tools -> Options -> Environment / Lazarus directory to the secondary subdir, namely /home/you/lazarus

In recent Lazarus versions, you are also given a screen to name the other important paths, so you would name the secondary sudirs in the 2ndary config.

Also, inside the /home/you/development/fpc/bin/x86_64-linux/fpc.cfg text file, all paths should rather point to your secondary copy. To make sure everything is fine, run startlazarus from within xterm and watch the errormessages. make sure all paths are found (very difficult currently).

You now have a secondary copy that which you can edit and recompile. Don't forget to close source files of the primary /usr/lib/lazarus.


Example 1: GIT and Release

This is to have both GIT and last release version of Lazarus.

1) Install Lazarus last release and check setup option 'create desktop shortcut', you will get 'Lazarus.lnk' on the desktop.

2) Get Lazarus from GIT and compile, then create a shortcut on your desktop for 'lazarus.exe' and rename it to 'Lazarus GIT.lnk'.

Then you can set the config dir for each version editing the shortcut path to the executable:

This is for release, because you don't change the primary config path parameter, the config will be saved in the default path:


For GIT, store the settings e.g. in the folder 'C:\lazgitcfg\':

C:\FPC\laz\startlazarus.exe --primary-config-path=C:\lazgitcfg

Installation of multiple Lazarus

Windows - Using the installer

On Windows the installer (Version 1.1) can create a secondary installation. And it will ask for a folder to store the config.

  • Install:
    • Make sure you back up ALL your existing configurations BEFORE you install.
    • AGAIN: Make sure you back up ALL your existing configurations BEFORE you install.
    • After install check that the correct config is used
      See the file "lazarus.cfg" in the installation directory. And Menu "View" > "IDE Internals" > "About IDE"
    • If you see a message about upgrading/downgrading the config, then the installation is incorrect. Press "Cancel"
  • Usage
    • Do not share packages between installations; rather you must have several independent copies of each package
    • Backup lpi and lps files (if you share projects). Ideally store sessions (lps) in the "IDE config directory"
      Menu: "Project" > "Project Options" > Session
  • Uninstall:
    • If you plan to uninstall: back up everything again
  • Update:
    • If you plan to update, back up everything again
    • After updating, check that the correct config is still being used
      See the file "lazarus.cfg" in the installation directory. And Menu "View" > "IDE Internals" > "About IDE"

The Windows Installer is able to create secondary installations, which allows you to have different versions installed that do not interfere with each other.

All you need to do is tick the checkbox "secondary installation" (when choosing the install directory), and follow the instructions. You will then be asked for a new empty folder where the config will be stored (this can be a subfolder in the install directory).

If you update an installation using the Windows Installer, it will detect when the selected directory contains a secondary install.

In order to always be able to quickly see which IDE you are using, and also to check that the correct config is loaded, it is advisable to make changes to some visual attributes. A possibility is to change the gutter color in the editor.

Windows - Adding a cross compiler install

The installation packages for cross compilers can be added to secondary installations, too. However, they will currently give a warning that the folder is not empty. This warning can be ignored.

Visually distinguish

To distinguish each Lazarus visually you can:

  • Set a different color for the gutter - the left column of the source editor where the line numbers and break points are shown.
  • Set the title of the IDE