Fedora Linux

Notice that renice does not permit the user to increase the priority of a process, even if the user lowered it in the first place. However, root can set any priority she chooses:

$ renice -5 27365
renice: 27365: setpriority: Permission denied
# renice 2 27365
27365: old priority 5, new priority 2
# renice -5 27365
27365: old priority 2, new priority -5

You can also adjust the priority of processes in System Monitor and KSysGuard using the options on the context menu (right-click on the process you wish to adjust).

4.9.3.4. ...starting and managing background processes?

When using the shell, you can start a process in the background by placing an ampersand after the command:

$ xboard &
[21771]
$ mc &
[21783]
$

The shell will display the PID of the background process, then immediately present a new prompt, permitting you to enter additional commands before the background command has finished executing.

You can display background processes using the jobs command:

$ jobs
[1]- Running xboard &
[2]+ Stopped . /usr/share/mc/bin/mc-wrapper.sh

Any program that attempts to communicate through the character interface, such as Midnight Commander ( mc ) in this example, will be stopped. Programs that communicate through the graphical user interface, such as xboard , are free to do so while running in the background.

To put a stopped command in the foreground so that you can interact with it, use the fg command:

$ fg 2

The argument is the job number as reported by the jobs command. You can stop the current foreground process by pressing Ctrl-Z.

To run a stopped process in the background, use the bg command:

$ fg 1
xboard
...User presses Ctrl-Z...
[1]+ Stopped xboard
$ jobs
[1]+ Stopped xboard
[2]- Stopped . /usr/share/mc/bin/mc-wrapper.sh
$ bg 1
[1]+ xboard &
$

You can use a percent sign and a job number instead of a PID when killing processes:

$ kill %1
$
[3]- Exit 15 xboard

4.9.4. Where Can I Learn More?

? Descriptions of each signal: the manpage for signal(7)

? The manpages for bash (for job control, including jobs , fg , bg , and the version of kill that is built into bash ), top , ps , and kill

4.10. Remote Management Using SSH

It's often useful to be able to log in to a machine remotely to perform some management operation. To enable secure remote access, Fedora provides the Secure Shell (SSH).

4.10.1. How Do I Do That?

SSH consists of two components: ssh (the client) and sshd (the server). The server is configured automatically when Fedora is installed.

To connect to a Fedora system from another Fedora system (or another Linux system), run the ssh client, providing the remote username and hostname (or IP address) as a single argument ( user @ host ). For example, to log in to a host with the IP address 10.0.0.1 using the user ID jon :

$ ssh [email protected]
The authenticity of host '10.0.0.1 (10.0.0.1)' can't be established.
RSA key fingerprint is 1d:dd:20:72:b1:0c:28:90:9a:ff:43:69:03:12:71:02.
Are you sure you want to continue connecting (yes/no)?
yes
Warning: Permanently added '10.0.0.1' (RSA) to the list of known hosts.
[email protected]'s password:
AnotherSecret