GIT External Diff / Merge tools

Occording to the GIT book, GIT supports these external Diff / Merge tools:

• [araxis] Araxis Merge - Commercial
• [bc3] Beyond Compare 3 - Commercial
• [diffuse] Diffuse - Open source
• [ecmerge] ECMerge - Commercial
• [emerge] Emerge (Emacs) - Open source
• [gvimdiff] gvimdiff - Open source
• [kdiff3] KDiff3 - Open source
• [meld] Meld merge - Open source
• [opendiff] opendiff - OS X Developer Tools
• [p4merge] P4Merge - Commercial
• [tkdiff] TkDiff - Open source
• [tortoisemerge] TortoiseMerge - Open source - [ Merge tool only ]
• [vimdiff] vimdiff - Open source
• [xxdiff] xxdiff - Open source
• [kompare] Kompare - Open source - [ Diff tool only ]

You can choose your prefered diff / merge tool by executing this command (Windows or Linux), in this case for my favorite kdiff3.

git config --global diff.tool kdiff3 

git config --global merge.tool kdiff3

The external diff is started using this command:

git difftool

You will probably get the error "The diff tool kdiff3 is not available as 'kdiff3'. external diff died, stopping at <filename>.", because GIT doesn't find your tool.
This can be resolved by adding your tool to the environment PATH variable, or by telling GIT where to find your tool(s):

git config --global difftool.kdiff3.path "C:/Program Files (x86)/KDiff3/kdiff3.exe"

git config --global mergetool.kdiff3.path "C:/Program Files (x86)/KDiff3/kdiff3.exe" 

Any configuration can be undone by executing:

git config --global <config item> --unset

e.g.

git config --global mergetool.kdiff3.path --unset