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4.15 How TRAMP finds and uses programs on the remote host

TRAMP depends on a number of programs on the remote host in order to function, including ls, test, find and cat.

In addition to these required tools, there are various tools that may be required based on the connection method. See Inline methods and External methods for details on these.

Certain other tools, such as perl (or perl5) and grep will be used if they can be found. When they are available, they are used to improve the performance and accuracy of remote file access.

User Option: tramp-remote-path

When TRAMP connects to the remote host, it searches for the programs that it can use. The variable tramp-remote-path controls the directories searched on the remote host.

By default, this is set to a reasonable set of defaults for most hosts. The symbol tramp-default-remote-path is a place holder, it is replaced by the list of directories received via the command getconf PATH on your remote host. For example, on Debian GNU/Linux this is /bin:/usr/bin, whereas on Solaris this is /usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/SUNWspro/bin. It is recommended to apply this symbol on top of tramp-remote-path.

It is possible, however, that your local (or remote ;) system administrator has put the tools you want in some obscure local directory.

In this case, you can still use them with TRAMP. You simply need to add code to your .emacs to add the directory to the remote path. This will then be searched by TRAMP when you connect and the software found.

To add a directory to the remote search path, you could use code such as:

;; We load TRAMP to define the variable.
(require 'tramp)
;; We have perl in "/usr/local/perl/bin"
(add-to-list 'tramp-remote-path "/usr/local/perl/bin")

Another possibility is to reuse the path settings of your remote account when you log in. Usually, these settings are overwritten, because they might not be useful for TRAMP. The place holder tramp-own-remote-path preserves these settings. You can activate it via

(add-to-list 'tramp-remote-path 'tramp-own-remote-path)

TRAMP caches several information, like the Perl binary location. The changed remote search path wouldn’t affect these settings. In order to force TRAMP to recompute these values, you must exit Emacs, remove your persistency file (see Connection caching), and restart Emacs.

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