These functions and data items provide information and operate on the
current process and user.
environ
A mapping object representing the string environment. For example,
environ['HOME'] is the pathname of your home directory (on some
platforms), and is equivalent to getenv("HOME") in C.
This mapping is captured the first time the os module is
imported, typically during Python startup as part of processing
site.py. Changes to the environment made after this time are
not reflected in os.environ, except for changes made by modifying
os.environ directly.
If the platform supports the putenv() function, this
mapping may be used to modify the environment as well as query the
environment. putenv() will be called automatically when
the mapping is modified.
Note:
Calling putenv() directly does not change
os.environ, so it's better to modify os.environ.Note:
On some platforms, including FreeBSD and Mac OS X, setting
environ may cause memory leaks. Refer to the system documentation
for putenv().
If putenv() is not provided, a modified copy of this mapping
may be passed to the appropriate process-creation functions to cause
child processes to use a modified environment.
If the platform supports the unsetenv() function, you can
delete items in this mapping to unset environment variables.
unsetenv() will be called automatically when an item is
deleted from os.environ.
chdir(
path)
fchdir(
fd)
getcwd(
)
These functions are described in ``Files and Directories'' (section
14.1.4).
ctermid(
)
Return the filename corresponding to the controlling terminal of the
process.
Availability: Unix.
getegid(
)
Return the effective group id of the current process. This
corresponds to the `set id' bit on the file being executed in the
current process.
Availability: Unix.
geteuid(
)
Return the current process' effective user id.
Availability: Unix.
getgid(
)
Return the real group id of the current process.
Availability: Unix.
getgroups(
)
Return list of supplemental group ids associated with the current
process.
Availability: Unix.
getlogin(
)
Return the name of the user logged in on the controlling terminal of
the process. For most purposes, it is more useful to use the
environment variable LOGNAME to find out who the user is,
or pwd.getpwuid(os.getuid())[0] to get the login name
of the currently effective user ID.
Availability: Unix.
getpgid(
pid)
Return the process group id of the process with process id pid.
If pid is 0, the process group id of the current process is
returned. Availability: Unix.
New in version 2.3.
getpgrp(
)
Return the id of the current process group.
Availability: Unix.
getpid(
)
Return the current process id.
Availability: Unix, Windows.
getppid(
)
Return the parent's process id.
Availability: Unix.
getuid(
)
Return the current process' user id.
Availability: Unix.
getenv(
varname[, value])
Return the value of the environment variable varname if it
exists, or value if it doesn't. value defaults to
None.
Availability: most flavors of Unix, Windows.
putenv(
varname, value)
Set the environment variable named varname to the string
value. Such changes to the environment affect subprocesses
started with os.system(), popen() or
fork() and execv().
Availability: most flavors of Unix, Windows.
Note:
On some platforms, including FreeBSD and Mac OS X,
setting environ may cause memory leaks.
Refer to the system documentation for putenv.
When putenv() is
supported, assignments to items in os.environ are automatically
translated into corresponding calls to putenv(); however,
calls to putenv() don't update os.environ, so it is
actually preferable to assign to items of os.environ.
setegid(
egid)
Set the current process's effective group id.
Availability: Unix.
seteuid(
euid)
Set the current process's effective user id.
Availability: Unix.
setgid(
gid)
Set the current process' group id.
Availability: Unix.
setgroups(
groups)
Set the list of supplemental group ids associated with the current
process to groups. groups must be a sequence, and each
element must be an integer identifying a group. This operation is
typical available only to the superuser.
Availability: Unix.
New in version 2.2.
setpgrp(
)
Calls the system call setpgrp() or setpgrp(0,
0) depending on which version is implemented (if any). See the
Unix manual for the semantics.
Availability: Unix.
setpgid(
pid, pgrp)
Calls the system call
setpgid() to set the process group id of the process with
id pid to the process group with id pgrp. See the Unix
manual for the semantics.
Availability: Unix.
setreuid(
ruid, euid)
Set the current process's real and effective user ids.
Availability: Unix.
setregid(
rgid, egid)
Set the current process's real and effective group ids.
Availability: Unix.
getsid(
pid)
Calls the system call getsid(). See the Unix manual
for the semantics.
Availability: Unix.
New in version 2.4.
setsid(
)
Calls the system call setsid(). See the Unix manual
for the semantics.
Availability: Unix.
setuid(
uid)
Set the current process' user id.
Availability: Unix.
strerror(
code)
Return the error message corresponding to the error code in
code.
Availability: Unix, Windows.
umask(
mask)
Set the current numeric umask and returns the previous umask.
Availability: Unix, Windows.
uname(
)
Return a 5-tuple containing information identifying the current
operating system. The tuple contains 5 strings:
(sysname, nodename, release, version,
machine). Some systems truncate the nodename to 8
characters or to the leading component; a better way to get the
hostname is socket.gethostname()or even
socket.gethostbyaddr(socket.gethostname()).
Availability: recent flavors of Unix.
unsetenv(
varname)
Unset (delete) the environment variable named varname. Such
changes to the environment affect subprocesses started with
os.system(), popen() or fork() and
execv(). Availability: most flavors of Unix, Windows.
When unsetenv() is
supported, deletion of items in os.environ is automatically
translated into a corresponding call to unsetenv(); however,
calls to unsetenv() don't update os.environ, so it is
actually preferable to delete items of os.environ.
