CDE/cde/doc/C/guides/man/man4/dtspcden.sgm

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<!-- (c) Copyright 1995 Hewlett-Packard Company. -->
<!-- (c) Copyright 1995 International Business Machines Corp. -->
<!-- (c) Copyright 1995 Sun Microsystems, Inc. -->
<!-- (c) Copyright 1995 Novell, Inc. -->
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<RefEntry Id="CDEMX.MAN87.rsml.1">
<RefMeta>
<RefEntryTitle>dtspcdenv</RefEntryTitle>
<ManVolNum>special file</ManVolNum>
</RefMeta>
<RefNameDiv>
<RefName><Filename>dtspcdenv</Filename></RefName>
<RefPurpose>environment Variable File for the CDE Subprocess Control Service
</RefPurpose>
</RefNameDiv>
<!-- *************************************************************************-->
<!-- **  (c) Copyright 1994 Hewlett-Packard Company-->
<!-- **  (c) Copyright 1994 International Business Machines Corp.-->
<!-- **  (c) Copyright 1994 Sun Microsystems, Inc.-->
<!-- **  (c) Copyright 1994 Novell, Inc.-->
<!-- *************************************************************************-->
<RefSect1>
<Title>DESCRIPTION</Title>
<Para>The CDE Subprocess Control service provides the
ability for a process running on one system to
invoke another process on a different system.
By default, the environment variables of the
parent process are passed unmodified to the
child process (on the remote host);
however, there are some environment
variables that are given special handling.
In
addition, the user or system administrator can
specify environment variables that should be
modified when they are passed to the child process.
</Para>
<Para>The system-wide environment files are:
<Filename>/etc/dt/config/dtspcdenv</Filename> and
<Filename>/usr/dt/config/dtspcdenv</Filename>
and the user-specific environment file is:
<Filename>$HOME/.dt/dtspcdenv</Filename>.
The file
<Filename>/usr/dt/config/dtspcdenv</Filename> is created
when CDE is installed.
This file may be overwritten
by subsequent CDE installations.
Consequently, local
variable definitions should be placed in the file
<Filename>/etc/dt/config/dtspcdenv</Filename> because this file is not
overwritten during installation.
</Para>
<Para>The environment variable files are evaluated in the following order:
</Para>
<ProgramListing>local host: <Filename>/usr/dt/config/dtspcdenv</Filename>
local host: <Filename>/etc/dt/config/dtspcdenv</Filename>
local host: <Filename>$HOME/.dt/dtspcdenv</Filename>
remote host: <Filename>/usr/dt/config/dtspcdenv</Filename>
remote host: <Filename>/etc/dt/config/dtspcdenv</Filename>
remote host: <Filename>$HOME/.dt/dtspcdenv</Filename>
</ProgramListing>
<Para>The precedence occurs in the reverse order of
evaluation.
Thus, variables in the remote
host's
<Filename>$HOME/.dt/dtspcdenv</Filename> file have the highest
precedence and variables in the local host's
<Filename>/etc/dt/config/dtspcdenv</Filename> file have the lowest
precedence.
In this context, the local host is the
host where a CDE client is running and
the remote host is the host where a remote
process will be started (on behalf of
the local client).
</Para>
<Para>Lines beginning with a numer symbol (#) are considered
comments and are not processed.
</Para>
<Para>The syntax for a non-commented line is:
</Para>
<InformalExample Remap="indent">
<ProgramListing>VAR_NAME=some_value
</ProgramListing>
</InformalExample>
<Para>where
<Emphasis>VAR_NAME</Emphasis> is the name of an
environment variable and
<Emphasis>some_value</Emphasis> is the value assigned to the variable.
</Para>
<Para>If
<Emphasis>some_value</Emphasis> contains a variable reference,
the reference will be replaced by the variable's
value.
For example, if a CDE client has the
following definition in its environment:
</Para>
<InformalExample Remap="indent">
<ProgramListing>PATH=/bin:/sbin:/usr/local/bin
</ProgramListing>
</InformalExample>
<Para>and the following definition occurs in one of the
environment files:
</Para>
<InformalExample Remap="indent">
<ProgramListing>PATH=/opt/foo/bin:$PATH
</ProgramListing>
</InformalExample>
<Para>then before the remote process is executed,
<SystemItem Class="EnvironVar">PATH</SystemItem>
will be expanded to:
</Para>
<InformalExample Remap="indent">
<ProgramListing>PATH=/opt/foo/bin:/bin:/sbin:/usr/local/bin
</ProgramListing>
</InformalExample>
<Para>The environment variable names may consist of
letters, digits or underscores and may be
enclosed in curly braces.
The environment variable files may contain
"unset &lt;variable_name>" commands to prevent
an environment variable from being propagated
to the remote process.
For example, the following line would
prevent the variable
<Emphasis>LIB_PATH</Emphasis> from being
propagated to the remote process:
</Para>
<InformalExample Remap="indent">
<ProgramListing>unset LIB_PATH
</ProgramListing>
</InformalExample>
</RefSect1>
<RefSect1>
<Title>ENVIRONMENT VARIABLES</Title>
<Para>The
<Command>dtspcd</Command> daemon treats the following variables specially:
</Para>
<VariableList>
<VarListEntry>
<Term><SystemItem Class="EnvironVar">DISPLAY</SystemItem></Term>
<ListItem>
<Para>If
<SystemItem Class="EnvironVar">DISPLAY</SystemItem> is set to "unix:&lt;n>", "local:&lt;n>" or ":&lt;n>"
(where &lt;n> is the screen number), then before the
remote process is executed,
<SystemItem Class="EnvironVar">DISPLAY</SystemItem> is changed to the name of the local host and
the screen number is preserved.
</Para>
</ListItem>
</VarListEntry>
<VarListEntry>
<Term><SystemItem Class="EnvironVar">HOME</SystemItem></Term>
<ListItem>
<Para>Before the remote process is executed,
<SystemItem Class="EnvironVar">HOME</SystemItem> is set
to the value of the user's home directory in
the password file on the remote host.
</Para>
</ListItem>
</VarListEntry>
<VarListEntry>
<Term><SystemItem Class="EnvironVar">SHELL</SystemItem></Term>
<ListItem>
<Para>If
<SystemItem Class="EnvironVar">SHELL</SystemItem> is not in the parent processes environment,
<SystemItem Class="EnvironVar">SHELL</SystemItem> is set to the value of the user's shell in
the password file on the remote host.
</Para>
</ListItem>
</VarListEntry>
<VarListEntry>
<Term><SystemItem Class="EnvironVar">PWD</SystemItem></Term>
<ListItem>
<Para>The variable
<SystemItem Class="EnvironVar">PWD</SystemItem> is not propagated to
the remote host.
Note that the above variables will be
overridden by their corresponding definitions
in an environment file.
</Para>
</ListItem>
</VarListEntry>
</VariableList>
</RefSect1>
<RefSect1>
<Title>EXAMPLES</Title>
<Para>The following definition sets the variable
<Emphasis>FOO_BIN_PATH</Emphasis> to the value
<Filename>/var/foo/bin</Filename>: <Literal>FOO_BIN_PATH=/var/foo/bin</Literal></Para>
</RefSect1>
<RefSect1>
<Title>FILES</Title>
<VariableList>
<VarListEntry>
<Term><Filename>/usr/dt/config/dtspcdenv</Filename></Term>
<ListItem>
<Para>System-wide, installed environment variable definitions
used when a process is executed
</Para>
</ListItem>
</VarListEntry>
<VarListEntry>
<Term><Filename>/etc/dt/config/dtspcdenv</Filename></Term>
<ListItem>
<Para>System-wide, locally defined environment variable definitions
used when a process is executed
</Para>
</ListItem>
</VarListEntry>
<VarListEntry>
<Term><Filename>$HOME/.dt/dtspcdenv</Filename></Term>
<ListItem>
<Para>User-specific environment variable definitions used
when a process is executed
</Para>
</ListItem>
</VarListEntry>
</VariableList>
</RefSect1>
<RefSect1>
<Title>SEE ALSO</Title>
<Para>&cdeman.dtspcd;.
</Para>
</RefSect1>
</RefEntry>
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