.TH USE 1 "$Date$" "Usepackage" "User Commands"
.SH NAME
usepackage \- 
.I Usepackage
Environment Manager
.SH SYNOPSIS
See 
.IR use(1) .
.SH DESCRIPTION
.I Usepackage
is an environment management program. It is based on the principle of
.I packages
\- collections of executables that share a common set of necessary
environment variables, such as PATH, MANPATH or LD_LIBRARY_PATH.
.PP
For each given
.IR package ,
.B use
sources the appropriate environment information into the current shell.
The environment information is specified in packages files, see
.IR PACKAGES .
.PP
The
.B usepackage
executable is the backend program used to generate environment information 
suitable for sourcing into a running shell. The
.B use
frontend should be invoked to actually effect changes to the environment,
see
.IR use(1) .
.SS OPTIONS
.TP
.I \-v
Output verbose information to the standard error stream.
.TP
.I \-s
Silence warnings for un-matched packages. This is useful in a shell
.I rc
script when a package is known not to be available on all architectures that 
the shell is used on, see
.IR PACKAGES .
.TP
.I \-c
Force
.I csh
style environment output.
.TP
.I \-b
Force bourne shell style environment output.
.TP
.I \-f file
Specify an alternate initial configuration file, see
.IR PACKAGES .
.TP
.I \-l
List available packages and groups, see
.IR ANNOTATIONS
and
.IR GROUPS .
.SH PACKAGES
.I Usepackage
reads package environment information from the configuration file as follows:
.SS LOAD ORDER
When
.I Usepackage
starts up, it loads an initial configuration file, the name of this file may 
be given on the command line (see
.IR OPTIONS ),
otherwise it defaults to the builtin name "usepackage.conf" (see
.IR FILES ).
This file is located by searching along a path which defaults to:
.PP
.nf
     @sysconfdir@:~:.
.fi
.PP
This path may be overridden with the PACKAGES_PATH environment variable
(see
.IR ENVIRONMENT ).
A packages file may contain inclusion directives which cause the sourcing of 
other files at given points. An inclusion directive looks like:
.PP
.nf
     (include file-name)
.fi
.PP
The same location mechanism is used to find "file-name" as for the initial
configuration file. A package file name may also be given as an absolute file 
name or may be shell-style user directory, tilde (~), relative.
.SS SYNTAX
A package file consists of comments, delimited by a leading hash (#), 
or package definitions of the form: 
.PP
.nf
     package [arch [os [version [host [shell]]]]]
          [<= requires ...] : setting [, setting ...] ;
.fi
.PP
The
.IR package ,
.IR arch ,
.IR os ,
.IR version ,
.IR host ,
and
.I shell
parts may be simple shell-style patterns of the form:
.TP 15
*
matches anything.
.TP
foo*
matches "foo", "foobar" etc.
.TP
{foo,bar}
matches "foo" or "bar".
.PP
The
.I requires
list specifies the names of other packages which must be sourced into the
environment before the settings for this package are processed.
.PP
A
.I setting
is either a variable definition, an alias definition (both described below)
or a section of text to be directly evaluated in the shell, delimited with
.IR <[
and
.IR ]> ,
for example:
.PP
.nf
     <[ /usr/local/bin/test-init ]>
.fi
.PP
When
.I Usepackage
searches for the definition for a particular package, it compares each line
in the packages file against the name of the package given (package) and
system-dependant information for the execution host, as obtained by
.IR uname (2).
This information is the hardware implementation (platform), the operating 
system name (os), the operating system version (version) and the hostname
(host). Comparisons are case-insensitive. If a match is obtained then the 
given variable definitions and script sections are processed to modify the
environment. A  variable definition may have one of the following forms:
.PP
.nf
     var-name = "string"
     var-name = path-list
     var-name += path-list
     var-name += "string"
     var-name =+ path-list
     var-name =+ "string"
.fi
.PP
The first sets the given variable to a literal string value, the
second sets the given variable to a path list, the third prepends the 
current value of a variable with the given path list, and the fourth 
interprets the literal string as a path list and prepends it to the current 
value of the variable. The fourth and fifth forms do the same, but append to
the current value of the variable. Path lists are colon (:) separated lists of 
directories and may contain shell-style tilde (~), user-relative, directories 
which will be expanded automatically (except when the path list is given as a 
literal string). When pre-pending paths to a variable, duplicate paths are 
removed from the original value first.
.PP
In addition,
.I Usepackage
can optionally test for the existence of paths before setting or adding them
to variables. This is done with the test form of the above operators:
.PP
.nf
     var-name ?= path-list
     var-name ?+= path-list
     var-name ?+= "string"
.fi
.PP
These operate as per the definitions above, but will ignore path components
that don't exist.
.PP
An alias definition has one of the following forms:
.PP
.nf
     alias name = name
     alias name = path
     alias name = "string"
.fi
.PP
These will define a matching shell alias.
.SS GROUPS
In addition to the package definitions in a packages file, there may also be
group definitions. These have the following syntax:
.PP
.nf
     group := package [, package ...] ;
.fi
.PP
.I Usepackage
searches for a given package name in the defined groups first, if the given
name matchs a group name then the packages defined as part of that group are
sourced into the environment together. A group definition may not reference
other groups and may not contain patterns.
.SS ANNOTATIONS
In order to give useful package information to the user, annotations may be
placed in the packages file that give summaries of packages. These annotations
have the form:
.PP
.nf
     >> name : "description" <<
.fi
.PP
.I Usepackage
collects these annotations together and displays them when called with the
.I -l
flag, see
.IR OPTIONS .
These annotations have no impact on the package mechanism and need not
necessarily be beside or correspond to the package definitions (although
this is the sensible way to arrange things).
.SS EXAMPLE
The following fragment of a packages file illustrates the main features:
.PP
.nf
     # GNU software is available everywhere:

     >> GNU : "The GNU project software" <<

     GNU :                     PATH += /usr/local/gnu/bin,
                               MANPATH += /usr/local/gnu/man ;

     # CVS requires RCS which is found in the GNU package, but
     # is only available on SPARC Solaris machines:

     >> CVS : "Concurrent Versions System revision control" <<

     CVS sun4* SunOS 5.* <= GNU :
                               CVSROOT = /usr/src/cvsroot,
                               CVSEDITOR = "vi",
                               PATH += /usr/local/cvs/bin,
                               MANPATH += /usr/local/cvs/man ;

     # User bin directories (Solaris will run SunOS 4 binaries):
     # (Only added to the path if the directories actually exist)

     >> user : "User's own programs" <<

     user sun4* SunOS :        PATH ?+= ~/bin/sun4 ;
     user sun4* SunOS 5.* :    PATH ?+= ~/bin/solaris ;
     user alpha OSF :          PATH ?+= ~/bin/alpha ;

     # Useful aliases:

     aliases : alias more = less,
               alias ls = "ls --color",
               alias cc = /usr/bin/gcc ;

     # Special function for zsh:
     
     >> zsh-function : "Special zsh function" <<
     
     zsh-function * * * * zsh :
           <[ hello() { echo "Hello World!"; } ]> ;

     # include standard packages:

     (include packages.standard)

     # security hole:

     dot :                     PATH += . ;

     # groups:

     user-setup := standard, user ;
     programmer-setup := standard, CVS, user, dot ;
.fi
.PP
Note the use of Operating System version numbers to distinguish between
SunOS 4 and Solaris (SunOS 5), the use of "sun4*" to match the multiple
different platform versions of SPARC machines (sun4m, sun4c, etc.) and the
fact that package "user" on a SPARC Solaris machine will match both of the 
first two lines of the "user" package section, resulting in the "solaris"
directory and the "sun4" directory being added into the PATH.
.PP
Assuming the appropriate shell setup script has been sourced - see
.IR use(1)
- then the following command will cause the CVS environment (including the
GNU environment) to be sourced:
.PP
.nf
     $ use CVS
.fi
.PP
Note that on a DEC Alpha machine, this will generate a warning like:
.PP
.nf
     $ use CVS
     warning: no match for package `CVS' on this host.
.fi
.PP
In a shell script which is executed on a number of different platforms (such
as the shell startup script). These warnings may be silenced (see
.IR OPTIONS ).
.SH FILES
.TP 15
.SB @pkgdatadir@/usepackage.conf
The default master packages file.
.TP
.SB @pkgdatadir@/use.csh
Shell setup for csh and derivatives.
.TP
.SB @pkgdatadir@/use.bsh
Shell setup for bourne shell and derivatives.
.TP
.SB @pkgdatadir@/use.ksh
Shell setup for ksh.
.TP
.SB @bindir@/usepackage
The underlying
.I Usepackage
executable.
.SH ENVIRONMENT
Other than the reading and re-definition of environment variables for package 
setup,
.B use
also uses the following environment variables for user configuration:
.TP 15
.SB PACKAGES_PATH
Colon-separated path list giving the directories to search for configuration
files. Shell-style tilde (~) user-directory escapes are expanded.
.TP
.SB HOME
If present in the environment, this is used to provide the expansion for
the tilde (~) user-directory.
.TP
.SB SHELL
If present in the environment, the last path component of this is used for
shell matching (see
.IR SYNTAX )
and detecting the style of environment output that should be used (see
.IR OPTIONS ).
.SH COPYRIGHT
.nf
Usepackage Environment Manager
Copyright (C) 1995-2015  Jonathan Hogg  <me@jonathanhogg.com>
.fi
.PP
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
.PP
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
.PP
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
.SH SEE ALSO
use(1), csh(1), sh(1), ksh(1), env(1), environ(5), getenv(3C), uname(1),
uname(2)