Mini Shell

Why does "ps -aux" complain about a bogus '-'?

	According to the POSIX and UNIX standards, the above command asks to
	display all processes with a TTY (generally the commands users are
	running) plus all processes owned by a user named "x".  If that user
	doesn't exist, then ps will assume you really meant "ps aux".  The
	warning is given to gently break you of a habit that will cause you
	trouble if a user named "x" were created.

Why don't I see SMP (per-CPU) stats in top?

	You didn't enable it. Press '?' for built-in help or read the man
	page.  Per-CPU stats are disabled by default because they take up too
	much space.  Some Linux systems have hundreds of CPUs.

Why do long usernames get printed as numbers?

	The UNIX and POSIX standards require that user names and group names
	be printed as decimal integers when there is not enough room in the
	column.  Truncating the names, besides being a violation of the
	standard, would lead to confusion between names like MichelleRichards
	and MichelleRichardson.  The UNIX and POSIX way to change column
	width is to rename the column:

		ps -o pid,user=CumbersomeUserNames -o comm

	The easy way is to directly specify the desired width:

		ps -o pid,user:19,comm

Why is %CPU underreported for multi-threaded (Java, etc.) apps?

	You need to upgrade to the 2.6.10 kernel at least. Older kernels do
	not provide a reasonable way to get this information.

Why do ps and top show threads individually?

	The 2.4.xx kernel does not provide proper support for grouping
	threads by process.  Hacks exist to group them anyway, but such hacks
	will falsely group similar tasks and will fail to group tasks due to
	race conditions.  The hacks are also slow.  As none of this is
	acceptable in a critical system tool, task grouping is not currently
	available for the 2.4.xx kernel.  The 2.6.xx kernel allows for proper
	thread grouping and reporting.  To take advantage of this, your
	programs must use a threading library that features the CLONE_THREAD
	flag.  The NPTL pthreads provided by recent glibc releases use
	CLONE_THREAD.

What systems are supported?

	Linux 2.4.xx 2.6.xx and 3.xx are commonly tested and expected to work
	well.  SMP is well supported.  Multi-node cluster views require a
	multi-node /proc filesystem; without that you will see a single-node
	view.

Where to I send bug reports?

	You may use the Debian bug tracking system or send your report to
	procps@freelists.org (no subscription required) instead.

Why are there so many procps projects?

	The original maintainer seems to have had little time for procps.
	Whatever his reasons, the project didn't get maintained.  Starting in
	1997, Albert Cahalan wrote a new ps program for the package.  For the
	next few years, Albert quietly helped the Debian package maintainer
	fix bugs.  In 2001, Rik van Riel decided to do something about what
	appeared to be the lack of a maintainer.  He picked up the buggy old
	code in Red Hat's CVS and started adding patches.  Meanwhile, other
	people have patched procps in a great many ways.

	In 2002, Albert moved procps to http://procps.sourceforge.net.  This
	was done to ensure that years of testing and bug fixes would not be
	lost.  The major version number was changed to 3, partly to avoid
	confusing users and partly because the top program had been redone.

	After development essentially stopped on sourceforge.net, in 2011 the
	project found a new home at http://gitorious.org/procps.  This
	represents the Debian, Fedora and openSUSE fork of procps.  To avoid
	confusion and potential name clashes the package is now known as
	procps-ng (next generation), the version number was raised to 3.3.0
	and the library so-name changed to libprocps.so

What is being done to procps-ng at its new home?

	All programs are in the process of being modernized, both in terms of
	coding style and supporting documentation.  Autotools have been
	integrated and the library API has been expanded with many new fields
	supported such as control groups, supplementary groups, etc.  The top
	program has been rewritten offering many new capabilities while
	providing performance improvements up to 300%.

Why does ps get signal 17?

	No ps release has ever had this problem. Most likely your system has
	been broken into.  You might want to install a more recent version of
	the OS.  If you'd rather take your chances, simply upgrade procps.