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Python methods for executing system commands http://www.linux-field.com/?p=15

There are two common methods of executing system commands in Python:

Both require import OS

(1) Os.system

# Run System commands on only one sub-terminal and cannot get return information after command execution

System (command), Exit_status
Execute the command (a string) in a subshell.

# if the command line executes, the result is printed directly.

1 >>> os.system ('ls')2 04101419778.CHM   Bash      document    Media      py-Django   video3 each. wmv            Books     Downloads   Pictures  python4 all-20061022      Desktop   Examples    Project    Tools

(2) Os.popen

# This method not only executes the command but also returns the executed information object

Popen (command [, mode= ' R ' [, BufSize]]), pipe
Open a pipe to/from a command returning a file object.

For example:

1>>>tmp = Os.popen ('ls *.py'). ReadLines ()2>>>tmp3Out[21]:4['dump_db_pickle.py',5 'dump_db_pickle_recs.py',6 'dump_db_shelve.py',7 'initdata.py',8 '__init__.py',9 'make_db_pickle.py',Ten 'make_db_pickle_recs.py', One 'make_db_shelve.py', A 'peopleinteract_query.py', - 'reader.py', - 'testargv.py', the 'teststreams.py', - 'update_db_pickle.py', - 'writer.py']

The advantage is that the returned result is assigned to a variable to facilitate the processing of the program.

(3) using the module subprocess

1 Import subprocess 2 >>> subprocess.call (["cmd""arg1" "  arg2"],shell=true)

Get Return and output:

1 Import subprocess 2 p = subprocess. Popen ('ls', Shell=true, stdout=subprocess. PIPE, stderr=subprocess. STDOUT)3 for in p.stdout.readlines ():4     Print line ,5 retval = p.wait ()

(4) using module commands module

1>>>Importcommands2>>>dir (commands)3['__all__','__builtins__','__doc__','__file__','__name__','GetOutput','GetStatus','Getstatusoutput','Mk2arg','Mkarg']4>>> Commands.getoutput ("Date")5 'Wed June ten 19:39:57 CST'6>>>7>>> Commands.getstatusoutput ("Date")8(0,'Wed June ten 19:40:41 CST')

Note: subprocess is recommended when you execute a command's arguments or return with Chinese text, and the following error occurs if you use Os.popen:

1 Traceback (most recent):2File"./test1.py", line 56,inch<module>3 Main ()4File"./test1.py", line 45,inchMain5 Fax.sendfax ()6File"./mailfax/fax.py", Line 13,inchSendFax7 os.popen (cmd)8Unicodeencodeerror:'ASCII'Codec can'T encode characters in position 46-52:ordinal not InRange (+)

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Tags: Python, commands, subprocess, Popen

Go to Python to execute system command methods