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All distributions support Jconsole and JHS. Some include the Qt desktop, which can also be installed separately, see Qt IDE.


J and the Qt desktop have been tested and are supported on the following platforms:

  • Windows 32 - XP or later
  • Windows 64 - 7 or later
  • Mac 64 OSX - 10.6.8 or later
  • Linux 32/64 - Red Hat 6 or other distribution with Qt 4.8 (most popular distributions)
  • Raspberry Pi - any version with Raspbian OS

Note: both Windows XP and OSX 10.6.8 are no longer supported by their vendors and no longer receive security updates. Future support of J on those platforms is not guaranteed.


Download the appropriate file from j802/install. Some files are zips or tars that can be unzipped and moved anywhere on your machine. Others are installers that create a default installation.

The default J install folder is under HOME, and is j802 for 32 bit, or j64-802 for 64 bit systems.

Before running J, you should check that the profile script in the bin subdirectory points to the correct directories. To make changes, copy the profilex_template.ijs script to a new profilex.ijs script, and update that script.

Admin privilege is not required for a standard install or for web updates.

User and temp files are in HOME folder j802-user or j64-802-user.

Doing the install in a protected folder path such as "Program Files..." or /usr/... requires admin privilege and will require admin privilege for web updates. Installing in other than HOME can be a nuisance and has no compelling benefit with the possible exception of an install for Multiple Users.

JE (J Engine) is a shared library that executes J sentences and is the system core. JE is j.dll in Windows, in Linux, and libj.dylib in Mac.

JFE (J Front End) is a user interface to JE.

Jconsole is a console JFE. It is jconsole.exe in Windows and jconsole in Linux and Mac.

Unix hardlinks to JFE are not supported and symlinks must have an absolute path.

Folder Summary


  jinstall: j802          or j64-802
  juser:    j802-user     or j64-user-802


  Vista or later: \Users\name
  XP:             \Documents and Settings\name
  Linux:          /home/name
  Mac:            /Users/name


  J32 on Win 32: C:\Program Files
  J64 on Win 64: C:\Program Files
  J32 on Win 64: C:\Program Files (x86)
  Unix:          /usr/...

standard install:


system install:


custom install:


custom install with profilex.ijs:



If using the installer, this creates J folder j802 and Program Group j802 (j64-802 for Windows64).

Yellow J icon interrupts a running J program.

Gray J icon runs Jconsole (Ctrl+D exits).

Windows XP: HOME is "\Documents and Settings\username".

Linux and Raspberry Pi

Unzip and move to the target directory, usually ~/j802 or ~/j64-802.

Run Jconsole:

...> ~/j802/

To start Jconsole from any directory, create a symbolic link to the binary in a folder in PATH. For example,

...$ ln -s ~/j802/bin/jconsole jc
...$ sudo mv jc /usr/bin/jc


Standard install is to use Finder to copy j802 folder from the zip to your home folder.

Copy does a complete replace of an existing J folder and you need extra steps if there are files you want to protect or carry forward.

  • Green jqt icon runs JQt (if installed)
  • Grey jcon icon runs Jconsole
  • Red jhs icon runs the JHS server
  • Yellow jbrk icon interrupts a running J program.

To start Jconsole from any directory, create a symbolic link to the binary in a folder in PATH. For example,

...$ ln -s ~/j802/bin/jconsole jc
...$ sudo mv jc /usr/bin/jc

An option is to copy the j802 folder to Applications. This requires admin privilege for the install and for subsequent web updates. An Applications install can be used by other users.

Another option, for casual use, is to just run J from the mounted disk image.

Multiple Users

Multiple users can share a single J install. Different users automatically get their own user and temp folders in their HOME folder.You can share a standard install with the J folder in the HOME directory of the user who is primarily responsible for J and updates and maintenance.

Alternatively you can do the install (or move an existing install) to a folder you feel is more appropriate. If you move a Windows install you have to manually edit the jsoftware-j802 icon properties to reference the new location.

You will want to provide users a convenient way to run J and this varies across platforms.


To allow all users to see the jsoftware-j802 Program Group, copy it from your HOME Programs folder to the public Programs folder:

1. right click Start button and click Open 1. right click jsoftware-j802 and click copy 1. right click Start button and click Open All Users 1. right click Programs folder and click paste


Create desktop launch icons and symlinks as appropriate.


If you put j802 in Applications, the J icons are already there in the j802 folder. If J is somewhere else you can create alias links for the J icons in Applications as follows:

1. in J folder press ctrl, click red J icon, click Make Alias 1. drag j802 alias to Applications 1. rename alias to just be j802 1. repeat steps for yellow J icon if desired

Create symlinks as appropriate.

Customized User Folder

The normal folder for user and temp files is HOME j802-user (or j64-802-user). Override this by creating profilex.ijs in your J bin folder.

bin\profilex_template.ijs is a template of what you want in profilex.ijs for the override. Study profilex_template.ijs before making your profilex.ijs file. Backup and be careful as errors may prevent J from starting properly.

USB Memory Stick

You can copy a J folder to a USB memory stick for a complete and portable J system. If you want the J user folders to be on the memory stick you need to create a profilex.ijs file in the memory stick J bin folder. See Customized User Folder for more information. You will want to edit profilex.ijs to have user in the install folder.

If you don't put profilex.ijs in the J folder on the memory stick, the J system will use HOME for the user folder.


Uninstall a J system by deleting the install folder, user folder(s), launch commands, icons, and shortcuts.

If you aren't sure where the J folders are, run J to get the information:


Don't delete the user folder if you want to keep those files for a new J install.

A multi-user install will have user folders in each users home folder.


Delete the J program group by clicking Start|All Programs then right clicking the J program group and selecting delete.

If you registered J as a COM server you can unregister it by running

....> regsvr32 /u [path to J install folder]\j.dll