cpython/Lib/commands.py

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# Module 'commands'
#
# Various tools for executing commands and looking at their output and status.
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#
# NB This only works (and is only relevant) for UNIX.
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# Get 'ls -l' status for an object into a string
#
def getstatus(file):
return getoutput('ls -ld' + mkarg(file))
# Get the output from a shell command into a string.
# The exit status is ignored; a trailing newline is stripped.
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# Assume the command will work with '{ ... ; } 2>&1' around it..
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#
def getoutput(cmd):
return getstatusoutput(cmd)[1]
# Ditto but preserving the exit status.
# Returns a pair (sts, output)
#
def getstatusoutput(cmd):
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import posix
pipe = posix.popen('{ ' + cmd + '; } 2>&1', 'r')
text = pipe.read()
sts = pipe.close()
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if sts == None: sts = 0
if text[-1:] == '\n': text = text[:-1]
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return sts, text
# Make command argument from directory and pathname (prefix space, add quotes).
#
def mk2arg(head, x):
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import posixpath
return mkarg(posixpath.join(head, x))
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# Make a shell command argument from a string.
# Two strategies: enclose in single quotes if it contains none;
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# otherwise, enclose in double quotes and prefix quotable characters
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# with backslash.
#
def mkarg(x):
if '\'' not in x:
return ' \'' + x + '\''
s = ' "'
for c in x:
if c in '\\$"`':
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s = s + '\\'
s = s + c
s = s + '"'
return s