Returns a string map view of this process builder's environment.
Whenever a process builder is created, the environment is
initialized to a copy of the current process environment (see
System.getenv()). Subprocesses subsequently started by
this object's start() method will use this map as
their environment.
The returned object may be modified using ordinary Map operations. These modifications will be
visible to subprocesses started via the start()
method. Two ProcessBuilder instances always
contain independent process environments, so changes to the
returned map will never be reflected in any other
ProcessBuilder instance or the values returned by
System.getenv.
If the system does not support environment variables, an empty map is returned.
The returned map does not permit null keys or values.
Attempting to insert or query the presence of a null key or
value will throw a NullPointerException.
Attempting to query the presence of a key or value which is not
of type String will throw a ClassCastException.
The behavior of the returned map is system-dependent. A
system may not allow modifications to environment variables or
may forbid certain variable names or values. For this reason,
attempts to modify the map may fail with
UnsupportedOperationException or
IllegalArgumentException
if the modification is not permitted by the operating system.
Since the external format of environment variable names and values is system-dependent, there may not be a one-to-one mapping between them and Java's Unicode strings. Nevertheless, the map is implemented in such a way that environment variables which are not modified by Java code will have an unmodified native representation in the subprocess.
The returned map and its collection views may not obey the
general contract of the Object.equals and
Object.hashCode methods.
The returned map is typically case-sensitive on all platforms.
If a security manager exists, its
checkPermission method
is called with a
RuntimePermission ("getenv.*") permission.
This may result in a SecurityException being thrown.
When passing information to a Java subprocess, system properties are generally preferred over environment variables.
SecurityException
| if a security manager exists and its
checkPermission
method doesn't allow access to the process environment |
Runtime.exec(String[],String[],java.io.File), System.getenv()
Diagram: Process