Initial revision

Lib/commands.py

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+# Module 'commands'
+#
+# Various tools for executing commands and looking at their output and status.
+
+import rand
+import posix
+import path
+
+
+# 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.
+# Assume the command will work with ' >tempfile 2>&1' appended.
+# XXX This should use posix.popen() instead, should it exist.
+#
+def getoutput(cmd):
+	return getstatusoutput(cmd)[1]
+
+
+# Ditto but preserving the exit status.
+# Returns a pair (sts, output)
+#
+def getstatusoutput(cmd):
+	tmp = '/usr/tmp/wdiff' + `rand.rand()`
+	sts = -1
+	try:
+		sts = posix.system(cmd + ' >' + tmp + ' 2>&1')
+		text = readfile(tmp)
+	finally:
+		altsts = posix.system('rm -f ' + tmp)
+	if text[-1:] = '\n': text = text[:-1]
+	return sts, text
+
+
+# Return a string containing a file's contents.
+#
+def readfile(fn):
+	fp = open(fn, 'r')
+	a = ''
+	n = 8096
+	while 1:
+		b = fp.read(n)
+		if not b: break
+		a = a + b
+	return a
+
+
+# Make command argument from directory and pathname (prefix space, add quotes).
+#
+def mk2arg(head, x):
+	return mkarg(path.cat(head, x))
+
+
+# Make a shell command argument from a string.
+# Two strategies: enclose in single quotes if it contains none;
+# otherwis, enclose in double quotes and prefix quotable characters
+# with backslash.
+#
+def mkarg(x):
+	if '\'' not in x:
+		return ' \'' + x + '\''
+	s = ' "'
+	for c in x:
+		if c in '\\$"':
+			s = s + '\\'
+		s = s + c
+	s = s + '"'
+	return s