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1 files changed, 46 insertions, 2 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index 8d38601201..996d045aa3 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -10021,6 +10021,12 @@ In this example we see that the combination of the four packages takes
102.3@tie{}MiB in total, which is much less than the sum of each closure
since they have a lot of dependencies in common.
+When looking at the profile returned by @command{guix size}, you may
+find yourself wondering why a given package shows up in the profile at
+all. To understand it, you can use @command{guix graph --path -t
+references} to display the shortest path between the two packages
+(@pxref{Invoking guix graph}).
+
The available options are:
@table @option
@@ -10081,8 +10087,9 @@ directly to the @command{dot} command of Graphviz. It can also emit an
HTML page with embedded JavaScript code to display a ``chord diagram''
in a Web browser, using the @uref{https://d3js.org/, d3.js} library, or
emit Cypher queries to construct a graph in a graph database supporting
-the @uref{https://www.opencypher.org/, openCypher} query language.
-The general syntax is:
+the @uref{https://www.opencypher.org/, openCypher} query language. With
+@option{--path}, it simply displays the shortest path between two
+packages. The general syntax is:
@example
guix graph @var{options} @var{package}@dots{}
@@ -10235,6 +10242,29 @@ collected.
@end table
+@cindex shortest path, between packages
+Often, the graph of the package you are interested in does not fit on
+your screen, and anyway all you want to know is @emph{why} that package
+actually depends on some seemingly unrelated package. The
+@option{--path} option instructs @command{guix graph} to display the
+shortest path between two packages (or derivations, or store items,
+etc.):
+
+@example
+$ guix graph --path emacs libunistring
+emacs@@26.3
+mailutils@@3.9
+libunistring@@0.9.10
+$ guix graph --path -t derivation emacs libunistring
+/gnu/store/@dots{}-emacs-26.3.drv
+/gnu/store/@dots{}-mailutils-3.9.drv
+/gnu/store/@dots{}-libunistring-0.9.10.drv
+$ guix graph --path -t references emacs libunistring
+/gnu/store/@dots{}-emacs-26.3
+/gnu/store/@dots{}-libidn2-2.2.0
+/gnu/store/@dots{}-libunistring-0.9.10
+@end example
+
The available options are the following:
@table @option
@@ -10255,6 +10285,20 @@ List the supported graph backends.
Currently, the available backends are Graphviz and d3.js.
+@item --path
+Display the shortest path between two nodes of the type specified by
+@option{--type}. The example below shows the shortest path between
+@code{libreoffice} and @code{llvm} according to the references of
+@code{libreoffice}:
+
+@example
+$ guix graph --path -t references libreoffice llvm
+/gnu/store/@dots{}-libreoffice-6.4.2.2
+/gnu/store/@dots{}-libepoxy-1.5.4
+/gnu/store/@dots{}-mesa-19.3.4
+/gnu/store/@dots{}-llvm-9.0.1
+@end example
+
@item --expression=@var{expr}
@itemx -e @var{expr}
Consider the package @var{expr} evaluates to.