Java Reference
In-Depth Information
The single argument forms of
exec
are equivalent to passing
null
for
env
,
which means that the created process inherits the environment vari-
ables of its parent.
Environment variables are interpreted in a system-dependent way by
the child process's program. They can hold information such as the cur-
rent user name, the current working directory, search paths, or other
useful information that may be needed by a running program. The en-
vironment variables mechanism is supported because existing programs
on many different kinds of platforms understand them. You can get
the environment variables of the current runtime process from the
Sys-
tem.getenv
method, which returns an unmodifiable map of all the name/
value pairs. Individual values can be retrieved using the
System.getenv
method which takes a string argument representing the name of the en-
vironment variable. The preferred way to communicate between differ-
However, this remains the only means of querying and subsequently
modifying the environment when executing a non-Java program.
There remain two further forms of
exec
that allow the initial working dir-
ectory of the child process to be specified:
public Process
exec(String[] cmdArray, String[] env, File
dir)
throws IOException
public Process
exec(String command, String[] env, File dir)
throws IOException
The child process is given an initial working directory as specified by the
path of
dir
. If
dir
is
null
, the child process inherits the current working
directory of the parentas specified by the system property
user.dir
. The
one- and two-argument forms of
exec
are equivalent to passing
null
for
dir
.
