A Python module to customize the process title

author:	Daniele Varrazzo

The setproctitle module allows a process to change its title (as displayed by system tools such as ps, top or MacOS Activity Monitor).

Changing the title is mostly useful in multi-process systems, for example when a master process is forked: changing the children's title allows to identify the task each process is busy with. The technique is used by PostgreSQL and the OpenSSH Server for example.

The procedure is hardly portable across different systems. PostgreSQL provides a good multi-platform implementation: this module is a Python wrapper around PostgreSQL code.

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Installation

setproctitle is a C extension: in order to build it you will need a C compiler and the Python development support (the python-dev or python3-dev package in most Linux distributions). No further external dependencies are required.

You can use pip to install the module:

pip install setproctitle

You can use pip -t or virtualenv for local installations, sudo pip for a system-wide one... the usual stuff. Read pip or virtualenv docs for all the details.

Usage

Note

You should import and use the module (even just calling getproctitle()) pretty early in your program lifetime: code writing env vars may interfere with the module initialisation.

The setproctitle module exports the following functions:

setproctitle(title)

Set title as the title for the current process.

getproctitle()

Return the current process title.

The process title is usually visible in files such as /proc/PID/cmdline, /proc/PID/status, /proc/PID/comm, depending on the operating system and kernel version. These information are used by user-space tools such as ps and top.

setthreadtitle(title)

Set title as the title for the current thread.

getthreadtitle()

Get the current thread title.

The thread title is exposed by some operating systems as the file /proc/PID/task/TID/comm, which is used by certain tools such as htop.

Environment variables

A few environment variables can be used to customize the module behavior:

SPT_NOENV

Avoid clobbering /proc/PID/environ.

On many platforms, setting the process title will clobber the environ memory area. os.environ will work as expected from within the Python process, but the content of the file /proc/PID/environ will be overwritten. If you require this file not to be broken you can set the SPT_NOENV environment variable to any non-empty value: in this case the maximum length for the title will be limited to the length of the command line.

SPT_DEBUG

Print debug information on stderr.

If the module doesn't work as expected you can set this variable to a non-empty value to generate information useful for debugging. Note that the most useful information is printed when the module is imported, not when the functions are called.

Module status

The module can be currently compiled and effectively used on the following platforms:

• GNU/Linux
• BSD
• MacOS X
• Windows

Note that on Windows there is no way to change the process string: what the module does is to create a Named Object whose value can be read using a tool such as Process Explorer (contribution of a more useful tool to be used together with setproctitle would be well accepted).

The module can probably work on HP-UX, but I haven't found any to test with. It is unlikely that it can work on Solaris instead.