Convert the calling process into a daemon. To make the current Python process into a daemon process, you need two lines of code:

from grizzled.os import daemonize
daemonize.daemonize()

If daemonize() fails for any reason, it throws a DaemonError, which is a subclass of the standard OSError exception. also logs debug messages, using the standard Python logging package, to channel "grizzled.os.daemon".

Adapted from: http://software.clapper.org/daemonize/

See Also:

• Stevens, W. Richard. Unix Network Programming (Addison-Wesley, 1990).

Parameters

• no_close (bool): If True, don't close the file descriptors. Useful if the calling process has already redirected file descriptors to an output file. Warning: Only set this parameter to True if you're sure there are no open file descriptors to the calling terminal. Otherwise, you'll risk having the daemon re-acquire a control terminal, which can cause it to be killed if someone logs off that terminal.
• pidfile (str): Path to file to which to write daemon's process ID. The string may contain a ${pid} token, which is replaced with the process ID of the daemon. e.g.: "/var/run/myserver-${pid}"

Raises

DaemonError: Error during daemonizing

Determine whether the specified system command exists in the specified path.

Parameters

• command_name (str): (simple) file name of command to find
• path (str or sequence): Path string (or sequence of path elements) to use. Defaults to environment PATH.

Returns

Full path to the command, or None if not found.

Get the path separator for the current operating system. The path separator is used to separate elements of a path string, such as "PATH" or "CLASSPATH". (It's a ":" on Unix-like systems and a ";" on Windows.)

:rtype: str :return: the path separator

Run a command as a daemon. This method is really just shorthand for the following code:

from grizzled.os import daemonize
import os

daemonize(pidfile=pidfile)
os.execv(path, args)

Parameters

• path (str): Full path to program to run
• args (list of str): List of command arguments. The first element in this list must be the command name (i.e., arg0).
• pidfile (str): Path to file to which to write daemon's process ID. The string may contain a ${pid} token, which is replaced with the process ID of the daemon. e.g.: "/var/run/myserver-${pid}"

This function is intended to be used as a with statement context manager. It allows you to replace code like this:

original_directory = _os.getcwd()
try:
    _os.chdir(some_dir)
    what_you_want_to_do()
finally:
    _os.chdir(original_directory)

with something simpler:

from grizzled.os import working_directory

with working_directory(some_dir):
    what_you_want_to_do()

Parameters

• directory (str): directory in which to execute your code

Thrown by daemonize() when an error occurs while attempting to create a daemon.