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4.11 Selecting config files for user/host name completion

The variable tramp-completion-function-alist is intended to customize which files are taken into account for user and host name completion (see Filename completion). For every method, it keeps a set of configuration files, accompanied by a Lisp function able to parse that file. Entries in tramp-completion-function-alist have the form (method pair1 pair2 ...).

Each pair is composed of (function file). function is responsible to extract user names and host names from file for completion. There are two functions which access this variable:

— Function: tramp-get-completion-function method

This function returns the list of completion functions for method.

Example: 

          (tramp-get-completion-function "rsh")
          
               ⇒ ((tramp-parse-rhosts "/etc/hosts.equiv")
                   (tramp-parse-rhosts "~/.rhosts"))
— Function: tramp-set-completion-function method function-list

This function sets function-list as list of completion functions for method.

Example: 

          (tramp-set-completion-function "ssh"
           '((tramp-parse-sconfig "/etc/ssh_config")
             (tramp-parse-sconfig "~/.ssh/config")))
          
               ⇒ ((tramp-parse-sconfig "/etc/ssh_config")
                   (tramp-parse-sconfig "~/.ssh/config"))

The following predefined functions parsing configuration files exist:

tramp-parse-rhosts
This function parses files which are syntactical equivalent to ~/.rhosts. It returns both host names and user names, if specified.
tramp-parse-shosts
This function parses files which are syntactical equivalent to ~/.ssh/known_hosts. Since there are no user names specified in such files, it can return host names only.
tramp-parse-sconfig
This function returns the host nicknames defined by Host entries in ~/.ssh/config style files.
tramp-parse-shostkeys
SSH2 parsing of directories /etc/ssh2/hostkeys/* and ~/ssh2/hostkeys/*. Hosts are coded in file names hostkey_portnumber_host-name.pub. User names are always nil.
tramp-parse-sknownhosts
Another SSH2 style parsing of directories like /etc/ssh2/knownhosts/* and ~/ssh2/knownhosts/*. This case, hosts names are coded in file names host-name.algorithm.pub. User names are always nil.
tramp-parse-hosts
A function dedicated to /etc/hosts style files. It returns host names only.
tramp-parse-passwd
A function which parses /etc/passwd like files. Obviously, it can return user names only.
tramp-parse-netrc
Finally, a function which parses ~/.netrc like files. This includes also ~/.authinfo-style files.

If you want to keep your own data in a file, with your own structure, you might provide such a function as well. This function must meet the following conventions:

— Function: my-tramp-parse file

file must be either a file name on your host, or nil. The function must return a list of (user host), which are taken as candidates for user and host name completion.

Example: 

          (my-tramp-parse "~/.my-tramp-hosts")
          
               ⇒ ((nil "toto") ("daniel" "melancholia"))