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This section gives some standard operations on host objects, and some procedures that return some useful pathnames.
This variable has as its value the host object that describes the local host's file system.
Returns #t if object is a pathname host; otherwise returns
#f.
procedure+: host=? host1 host2
Returns #t if host1 and host2 denote the same
pathname host; otherwise returns #f.
procedure+: init-file-pathname [host]
Returns a pathname for the user's initialization file on host.
The host argument defaults to the value of local-host. If
the initialization file does not exist this procedure returns #f.
Under unix, the init file is called `.scheme.init'; under Windows
and OS/2, the init file is called `scheme.ini'. In either case, it
is located in the user's home directory, which is computed by
user-homedir-pathname.
procedure+: user-homedir-pathname [host]
Returns a pathname for the user's "home directory" on host. The
host argument defaults to the value of local-host. The
concept of a "home directory" is itself somewhat
implementation-dependent, but it should be the place where the user
keeps personal files, such as initialization files and mail.
Under unix, the user's home directory is specified by the HOME
environment variable. If this variable is undefined, the user name is
computed using the getlogin system call, or if that fails, the
geteuid system call. The resulting user name is passed to the
getpwnam system call to obtain the home directory.
Under OS/2, the user's home directory is specified by the HOME
environment variable. If this variable is undefined, but the
USERDIR and USER environment variables are defined, then
the user's home directory is `%USERDIR%\%USER%'. If only
USERDIR is defined, then the user's home directory is
`%USERDIR%\nouser'. If none of these variables is defined, then
the home directory is the root directory of the current drive.
Under Windows, the user's home directory is computed by examining
several environment variables, in the following order. If
HOMEPATH is defined, the home directory is
`%HOMEDRIVE%%HOMEPATH%'. If HOME is defined, the home
directory is `%HOMEDRIVE%%HOME%'. If USERDIR and
USERNAME are defined, the home directory is
`%USERDIR%\%USERNAME%'. If USERDIR and USER are
defined, the home directory is `%USERDIR%\%USER%'. If
USERDIR is defined, the home directory is
`%USERDIR%\nouser'. If none of these variables is defined, then
the home directory is the root directory of the current drive.
procedure+: system-library-pathname pathname
Locates pathname in MIT Scheme's system library directory. An
error of type condition-type:file-operation-error is signalled if
pathname cannot be located on the library search path.
(system-library-pathname "compiler.com")
=> #[pathname 45 "/usr/local/lib/mit-scheme/compiler.com"]
procedure+: system-library-directory-pathname pathname
Locates the pathname of a MIT Scheme system library directory. An error
of type condition-type:file-operation-error is signalled if
pathname cannot be located on the library search path.
(system-library-directory-pathname "options")
=> #[pathname 44 "/usr/local/lib/mit-scheme/options/"]
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