Add an "executable" option to the command and shell modules

The option will be passed to the Popen object created and will be used to
execute the command instead of the default shell.

command

@@ -60,6 +60,12 @@ options:
     version_added: "0.6"
     required: false
     default: null
+  executable:
+    description:
+      - change the shell used to execute the command. Should be an absolute path to the executable.
+    required: false
+    default: null
+    version_added: "0.9"
 examples:
    - code: "command: /sbin/shutdown -t now"
      description: "Example from Ansible Playbooks"
@@ -81,6 +87,7 @@ def main():
 
     shell = module.params['shell']
     chdir = module.params['chdir']
+    executable = module.params['executable']
     args  = module.params['args']
 
     if args.strip() == '':
@@ -94,7 +101,7 @@ def main():
     startd = datetime.datetime.now()
 
     try:
-        cmd = subprocess.Popen(args, shell=shell, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        cmd = subprocess.Popen(args, executable=executable, shell=shell, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         out, err = cmd.communicate()
     except (OSError, IOError), e:
         module.fail_json(rc=e.errno, msg=str(e), cmd=args)
@@ -140,11 +147,12 @@ class CommandModule(AnsibleModule):
         params = {}
         params['chdir'] = None
         params['shell'] = False
+        params['executable'] = None
         if args.find("#USE_SHELL") != -1:
             args = args.replace("#USE_SHELL", "")
             params['shell'] = True
 
-        r = re.compile(r'(^|\s)(creates|removes|chdir)=(?P<quote>[\'"])?(.*?)(?(quote)(?<!\\)(?P=quote))((?<!\\)(?=\s)|$)')
+        r = re.compile(r'(^|\s)(creates|removes|chdir|executable)=(?P<quote>[\'"])?(.*?)(?(quote)(?<!\\)(?P=quote))((?<!\\)(?=\s)|$)')
         for m in r.finditer(args):
             v = m.group(4).replace("\\", "")
             if m.group(2) == "creates":
@@ -182,6 +190,13 @@ class CommandModule(AnsibleModule):
                 elif v[0] != '/':
                     self.fail_json(rc=259, msg="the path for 'chdir' argument must be fully qualified")
                 params['chdir'] = v
+            elif m.group(2) == "executable":
+                v = os.path.expanduser(v)
+                if not (os.path.exists(v)):
+                    self.fail_json(rc=258, msg="cannot use executable '%s': file does not exist" % v)
+                elif v[0] != '/':
+                    self.fail_json(rc=259, msg="the path for 'executable' argument must be fully qualified")
+                params['executable'] = v
         args = r.sub("", args)
         params['args'] = args
         return (params, params['args'])

shell

@@ -27,6 +27,12 @@ options:
       - cd into this directory before running the command (0.6 and later)
     required: false
     default: null
+  executable:
+    description:
+      - change the shell used to execute the command. Should be an absolute path to the executable.
+    required: false
+    default: null
+    version_added: "0.9"
 examples:
    - code: "shell: somescript.sh >> somelog.txt"
      description: Execute the command in remote shell