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System Sofware and User Accounts

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8 replies

by night-owl-24-7-365

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How to:
a. add and disable user accounts from the command line?
b. detect all the processes running on machine in use under a particular user account?
c. deinstall and install software?
d. determine the version number of any software package installed on system in use?
e. activate and deactivate software services like httpd, ftp, and talk?
f. boot to single user runlevel?

8 replies

by stress junkie

In the following examples the use of <> around a word indicates that you don't type the word as you see it; rather it is the name of a value. Example: means type the name of a user account. In all of these examples I will expect you to be running the commands from the root account.

Please be sure to rate this answer. If you do then I will answer your other two posts, if you have also raised the point value of them as well. :-)

a. add user:useradd, modify user account:usermod, delete user account:userdel, disable user account:passwd -l

Use the man pages for the details of each command as in: man userdel

b. ps -u

c. Some Linux distributions use the Red Hat Package Manager (rpm) application to install and remove software "packages". In these cases you should use the rpm package to install and rpm to remove these packages. Other Linux distributions do not use rpm, and some software is not available in rpm package format. In these cases the software will almost always have detailed instructions. Usually that will involve downloading a compressed archive file, decompressing the archive file, using and the make utility to compile the application and install it.

d. If a software package has been installed using rpm then you can use the following command: rpm -q -a. If rpm was not used to install the software then sometimes the software executables or library files have the version in their name. Lastly, software that can be run from the command line will often accept the option --version on the command line as in: man --version. Consult the man pages about any executable before you try to run it.

by stress junkie

e. Edit the /etc/services file. Each network service offered by the machine is listed there. If you want to disable a service then put a # as the first letter on the line listing that service. If you want to disable a service that has a # on its line then delete the #. If you want to install a service that is not listed then you have to add a new line to this file to describe the service. In all cases chages will not take effect until you restart the network or just reboot the machine.

f. If the machine is already running then you can enter the command: init 1. If the machine is booting then you hopfully use a boot manager like lilo or grub. In that case you can add the number 1 or -1 to the boot command line interactively when the splash screen for the boot manager shows up.

Note: my answers exceeded the character limit for a single post even though I tried to be brief but still helpful. You should put fewer questions in each post. And don't reject these answers because they are not detailed enough. We can't write books for these posts.

by stress junkie

In the answer to question e it looks like I said how to disable a service twice. The second should read that in order to ENABLE a service that has a # as the first character on the line that describes the service then remove the # character.

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