I got problems setting file permissions please help me out with the commands i know its "chmod" but think i am not setting it the right way.
Also help me out with the command to view all the users entitled to use the machine and the groups they are in.

man chmod
+/-x toggles the executable flag
+/-w toggles the write flag
+/-r toggles the read flag

all groups are listed in /etc/group

chmod xyz filename

where x is for user/owner, y is for group and z is for users not from that group.
permissions:
4 - read
2 - write
1 - execute

so if you'd like to change permissions from read to read+write (4+2) type

$chmod 644 filename

now you have read/write access, but group and others have only read access.
use execute bit for executables and directories

There are additional permissions.
These are the set group or user ID bit (s), the sticky bit (t), and X.
These permissions can be applied to directories or files. The sticky, SUID, or SGID bits can be set the same way other other file and directory permissions are set.
Only root is permitted to turn the sticky bit on or off. In addition the sticky bit applies to anyone who accesses the file. The syntax for setting the sticky bit on the /tmp directory is as follows:

chmod +t /tmp

So the output of ls -l will look either like this,
->
drwxrwxrwt 5 sys sys 543 May 21 02:41 tmp

or like this->
drwxrwxrwT 5 sys sys 543 May 21 02:41 tmp





Thanks,

Avirup