Hi,

I am reading linux essentials and there's a question asking:

what could be the correct approach in answering this question?

IMO, manual pages of ps, ptree, pwdx, top etc. commands deal with processes and various options associated with these commands.

http://linux.die.net/man/1/ps
http://linux.die.net/man/1/pstree
http://linux.die.net/man/1/top

Also check references given at the end of these links for more "processes" related manual pages.

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Most commands are in the following 4 directories:However there are a LOT of commands.

When they're referring to NAME, they refer to the name and short description you see when you perform a man page. For instance, her is a web-based view of the "ps" command.

http://unixhelp.ed.ac.uk/CGI/man-cgi?ps

And as you can see, it says in here that this command reports a snapshot of the current processes.

Their exercise is asking you to evaluate the commands which you have that can tell you about processes. I'm also doubting that they're asking you to do man pages on literally all of your available commands. Likely they've covered some of them so that you can refer back from what you've read in the book thus far.

A REALLY good thing to do here is to view the "SEE ALSO" section of that man page, where you'll see that it tells you to also check the following commands:And further, from those pages you may also learn of other process oriented commands. Although the ones here are pretty powerful already. Look at the size of the manual page for ps to get an idea.

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I think, I am mixed up by the question: what does it mean a command dealing with processes? I think all commands deal with processes in a way or so. And, what does it have to do with their man page?
Also, what are "process oriented commands"? as you kindly mentioned in your answer.

No. It's not about that all commands that somewhere deal with a process (though obviously every command generates a process), but here it's referening to those man pages which deal with "process" related commands, that is man pages of those command which, in any manner, gives information about system processes and various aspect of those system processes. You can find lots of commands, which we already mentioned above, related to processes.

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Some examples of commands which I feel do not deal with processes.

• The command ls lists files or directories.

• The command tar is used to archive files.

When you issue those commands, they do cause a process to occur, but their intent is to give you the result.

Sorry for superfluous verbiage, but process oriented commands was just intended to indicate commands which relate to information or control of processes in the system. For instance ps will list the processes running, and if you issue it as ps -ef it will list full information about all processes for all users, and also list information about the actual ps call you issued to obtain the result.

To me. Linux is A LOT about files, processes, and signals.

Everything has a file. The serial port, is a physical port, it has a driver, and you access the serial port via the file /dev/ttyS0. If you look at your /proc tree, you'll notice a lot of information about your system, including things like CPU temperature, and processes which are present on your system. For instance, if you perform the ps -ef command and see a bunch of processes, when you look in the /proc tree, you'll see sub-directories matching all the process PID numbers. And likewise underneath those directories you'll see files and further sub-directories which cover or govern the resources which those processes are using. This, by the way is not a place to play around; I'm just citing an observation about how the system works and is organized.

Processes are programs, plain and simple. They either are temporary; such as when you perform an ls command, or run forever, like crond.

Signals are a bit more complicated. They are one way which processes communicate, or how the kernel and processes communicate sometimes. For instance, KILL is a signal. Which you can send to a process using either the kill command or the signal command.

Sorry, maybe this offers more confusion. Are you working on a Linux system as you're reading? I feel it is very helpful to view and experience things in Linux on a live system which is running it.

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I AM working on different versions of linux as well as reading and have taken some courses as well. I really really found your answer helpful. I hope to see you even more when I send other questions in future. Thanks again!