8.15 Standard Module commands

 

The commands module contains wrapper functions for os.popen() which take a system command as a string and return any output generated by the command and, optionally, the exit status.

The commands module is only usable on systems which support os.popen() (currently Unix). It defines the following functions:

getstatusoutput (cmd)

Execute the string cmd in a shell with os.popen() and return a 2-tuple (status, output). cmd is actually run as { cmd ; } 2>&1, so that the returned output will contain output or error messages. A trailing newline is stripped from the output. The exit status for the command can be interpreted according to the rules for the C function wait().

getoutput (cmd)

Like getstatusoutput(), except the exit status is ignored and the return value is a string containing the command's output.

getstatus (file)

Return the output of "ls -ld file" as a string. This function uses the getoutput() function, and properly escapes backslashes and dollar signs in the argument.

Example:

>>> import commands
>>> commands.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> commands.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> commands.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
>>> commands.getoutput('ls /bin/ls')
'/bin/ls'
>>> commands.getstatus('/bin/ls')
'-rwxr-xr-x  1 root        13352 Oct 14  1994 /bin/ls'