Extend Tramp FAQ

* doc/misc/tramp.texi (Frequently Asked Questions): Improve index.
Recommend `small-temporary-file-directory' for ssh sockets.

(cherry picked from commit 0d466151109f41e84ec4183ba47d88dba1eb360c)

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 8bf9c06a53a90c0d29d67950bc94608e72d012cf..98e52ce5be1dc31da5912abcd9491bd4b5c2f87a 100644 (file)
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -5760,6 +5760,7 @@ connection-local value.
 @end group
 @end lisp
 
+@vindex XDG_DATA_HOME@r{, environment variable}
 If Emacs is configured to use the XDG conventions for the trash
 directory, remote files cannot be restored with the respective tools,
 because those conventions don't specify remote paths.  Such files must
@@ -6177,6 +6178,36 @@ as above in your @file{~/.emacs}:
 @end lisp
 
 
+@item
+I get an error @samp{unix_listener: path
+"/very/long/path/.cache/emacs/tramp.XXX" too long for Unix domain
+socket} when connectiong via @option{ssh} to a remote host.
+
+@vindex small-temporary-file-directory
+By default, @value{tramp} uses the directory @file{~/.cache/emacs/}
+for creation of OpenSSH Unix domain sockets.  On GNU/Linux, domain
+sockets have a much lower maximum path length (currently 107
+characters) than normal files.
+
+You can change this directory by setting the user option
+@code{small-temporary-file-directory} to another name, like
+
+@lisp
+@group
+(unless small-temporary-file-directory
+  (customize-set-variable
+   'small-temporary-file-directory
+   (format "/run/user/%d/emacs/" (user-uid)))
+  (make-directory small-temporary-file-directory t))
+@end group
+@end lisp
+
+@vindex XDG_RUNTIME_DIR@r{, environment variable}
+@t{"/run/user/UID"} is the value of the environment variable
+@env{XDG_RUNTIME_DIR}, which you can use instead via @code{(getenv
+"XDG_RUNTIME_DIR")}.
+
+
 @item
 How to ignore errors when changing file attributes?