procps is the package that has a bunch of small useful utilities that give information about processes using the /proc filesystem.
procps includes the programs ps, top, vmstat, w, kill, free, slabtop, and skill.
Browse Repository: http://procps.cvs.sourceforge.net/procps/procps/
Home Page: http://procps.sourceforge.net/index.html
Procps New Generation (procps-ng)
procps-ng is the Debian, Fedora and openSUSE fork of procps.
From their NEWS page,
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Did you notice the change in their versioning? See below, Eric Bélanger is asking about switching to procps-ng.
What happened to the Warning?
Did you remember bad syntax warning, when you type
ps -aux in old ps program.
Warning: bad ps syntax, perhaps a bogus ‘–’? See http://procps.sf.net/faq.html
This behavior is intended to aid in transitioning old scripts and habits. It is fragile, subject to change, and thus should not be relied upon.
Now this warning has been removed. You no longer get a warning.
I built a GNU Linux System from Scratch, I used Procps-ng-3.3.6. I don’t get this warning anymore. Did you still get this warning?
Proc File System
The proc filesystem provides a method of communication between kernel space and user space.
User space(see left) and Kernel Space(see right) are bridged using proc file system. Proc file system belongs to Kernel Space.
User space creatures can read the proc files. Sometime there are writable proc files that can be used to control the Kernel.
echo “1” > /proc/sys/net/ipv4/ip_forward
Controls whether the kernel will allow tcp forwarding. The default value is 0 which means forwarding is OFF.You can set this to 1 if you with to enable it.
Read More: http://en.wikipedia.org/wiki/Procfs