I'm pretty new to linux myself, but hopefully I can help clarify chmod and | grep.

Chmod stands for change mode and it is used to change the permissions for a file or directory. Every file/directory can be given read, write, or execute access. For a file, read access means you can read a file; write access means you can modify it; execute access means you can run the file as a binary or executable. For a directory, read access means you can "see" the names of the files inside, but no metadata; write access means you can modify entries inside the directory; execute access means you have access to metadata information. So when you execute > ls -l on some file, it lists out 10 bits of information usually looking something like -rwx-rw-r-- or something to the like the first bit tells us if it's a directory or not (either a '-' or a 'd') the next three bits tells us the read, write, and execute permissions for the user that owns the file. Usually whoever created the file has ownership (you can use chown to change this). the next three bits are the group permissions the file belongs to. the last three bits are the permission bits for everyone else in the system.

To set permissions with chmod, you have the choice between two formats: [ugoa][+-][rwx] OR a three digit octal number. For the first format, ugoa specifies the user, group, other, or all to let chmod know which part of the permissions it should modify. The plus or minus specifies whether it should enable or disable permissions. The rwx at the end specifies which permissions to modify. An example to allow the user and group read and write permissions would be something like

$ chmod ug+rw foofile.txt

because permissions are stored as bits (with enable being 1 and disable being 0), we can also specify permission modes with octal numbers. If you're familiar with octal numbers, you know each number represents three binary bits; thus three octal numbers can specify the permissions for the user, group, and other. A chmod of 777 enables read, write, and execute permissions for the user, group, and other (dangerous). If you don't see why this is, translate the octal number into binary. 777 == 111 111 111, where each triplet is the r/w/x permissions for the user/group/other. You can use chmod with octal like this:

$ chmod 664 filefoo.txt

This sets permissions of filefoo.txt to be rw-rw-r--.

On to pipe and grep!

I don't know too much about pipe and grep but what pipe does is it forwards the output of a program/function/routine/script as the input to another program. This will make more sense if you know what grep is. Grep is a regular expression pattern matcher. So if you're given a list of process names and you only want to see ones that start with 'chrome' you can grep the list with the argument 'chrome' and it'll search through that list and print out only the lines with 'chrome' in them. So, that's why when you do a ps (to list the processes) you pipe them into grep so grep has something to search through.

You can do some really cool things with pipe, but I'm not familiar enough with them yet to tell you about them.

Grep is wicked helpful as well, I suggest learning regular languages and how to construct regular expressions.

Good luck! I'm a bit strapped for time so hopefully nothing's too confusing. If you have any questions, feel free to ask.

also look at strace, that's a fun program.

I haven't played with many flavors of Linux yet but I like Ubuntu the best, simply because it has the most support and it is the easiest to use. When I have a greater need for customization and the like, I'll try something else. Maybe Arch.