Python Pocket Reference, 3rd Edition

The os System Module

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altsep

Alternative separator string or None (e.g., / for Windows).

extsep

The character which separates the base filename from the

extension (e.g.,

.).

pathsep

Character used to separate search path components, as

in

the

PATH

and

PYTHONPATH

shell variable settings (e.g.,

;

for

Windows,

:

for Unix).

defpath

Default search path used by os.exec*p* calls if there is no

PATH setting in the shell.

linesep

String used to terminate lines on current platform (e.g.,

\n

for POSIX,

\r

for Mac OS, and

\r\n

for MS-DOS and

Windows).

Shell Commands

These functions run programs in the underlying operating

system.

system(cmd)

Executes a command string cmd in a subshell process.

Returns the exit status of the spawned process. Unlike

popen, does not connect to cmd’s standard streams via

pipes. Hints: add an

& at the end of cmd to run the com-

mand in the background on Unix (e.g.,

os.

system('python main.py &')

); use a DOS start command

to launch programs easily on Windows (e.g.,

os.

system('start file.html')

).

startfile(filepathname)

Starts a file with its associated application. Acts like dou-

ble-clicking the file in Windows Explorer or giving the

filename as an argument to a DOS

start command (e.g.,

with

os.system('start path')). The file is opened in the

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Python Pocket Reference

application with which its extension is associated; ...