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Programming Python, Second Edition
book

Programming Python, Second Edition

by Mark Lutz
March 2001
Intermediate to advanced content levelIntermediate to advanced
1296 pages
38h 8m
English
O'Reilly Media, Inc.
Content preview from Programming Python, Second Edition

Script Execution Context

Python scripts don’t run in a vacuum. Depending on platforms and startup procedures, Python programs may have all sorts of enclosing context -- information automatically passed-in to the program by the operating system when the program starts up. For instance, scripts have access to the following sorts of system-level inputs and interfaces:

Current working directory

os.getcwd gives access to the directory from which a script is started, and many file tools use its value implicitly.

Command-line arguments

sys.argv gives access to words typed on the command line used to start the program that serve as script inputs.

Shell variables

os.environ provides an interface to names assigned in the enclosing shell (or a parent program) and passed in to the script.

Standard streams

sys.stdin, stdout, and stderr export the three input/output streams that are at the heart of command-line shell tools.

Such tools can serve as inputs to scripts, configuration parameters, and so on. In the next few sections, we will explore these context tools -- both their Python interfaces and their typical roles.

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Publisher Resources

ISBN: 0596000855Supplemental ContentCatalog PageErrata