I have a Shell command that I'd like to run in the background and I've read that this can be done by suffixing an & to the command which causes it to run as a background process but I need some more functionality and was wondering how to go about it:
I'd like the command to start and run in the background every time the system restarts.
I'd like to be able to able to start and stop it as and when needed just like one can do service apache2 start.
How can I go about this? Is there a tool that allows me to run a command as a service?
I'm a little lost with this.
Thanks
UNIX systems can handle as many processes as you need simultaneously (just open new shell windows if you're in a GUI), so running a process in the background is only necessary if you need to carry on using the current shell window for other things once you've run an application or process that keeps running.
To run a command called command in background mode, you'd use:
command &
This is a special character that returns you to the command prompt once the process is started. There are other special characters that do other things, more info is available here.
Take a look at the daemon command, which can turn arbitrary processes into daemons. This will allow your script to act as a daemon without requiring you to do a lot of extra work. The next step is to invoke it automatically at boot. To know the correct way to do that, you'll need to provide your OS (or, for Linux, your distribution).
Based on this article:
http:// felixmilea.com/2014/12/running-bash-commands-background-properly/
...another good way is with screen eg:
screen -d -m -s "my session name" <command to run>
from the screen manual:
-d -m
Start screen in detached mode. This creates a new session but doesn't attach to it. This is useful for system startup scripts.
i.e. you can close your terminal, the process will continue running (unlike with &)
with screen you can also reattach to the session later
Use nohup while directing the output to /dev/null
nohup command &>/dev/null &
For advanced job control with bash, you should look into the commands jobs bg and fg.
However, it seems like you're not really interested in running the command in the background. What you want to do is launch the command at startup. The way to do this varies depending on the Unix system you use, but try to look into the rc family of files (/etc/rc.local for example on Ubuntu). They contain scripts that will be executed after the init script.
Related
When I use this code below it works great for non cli programs like notepad. However, whenever I want to spawn another ruby script or executable, it takes over that command prompt window and I can not see my parent process anymore. How can I make the spawn command open the script in a new window?
pid = spawn(path)
Process.wait pid
I have already tried "start path" but that doesn't return the correct pid. I also tried Process.daemon, but that didn't even do anything. I believe I need to make it open another conhost.exe process because it starts two ruby.exe processes and two cmd.exe processes, but keeps only 1 conhost.exe process.
I am trying to writing a ruby script that spawns other scripts and manages them. Cross platform is ideal, but Windows compatible will do. Appreciate the help.
You can make use of this gem eye here to manage & monitor processes, works quite well with starting & stopping processes(using PID).
I want to be able to open an application on the command line, but instead of switching to the application, I want to stay on my terminal emulator. Is there a way of accomplishing this? I am using OS X.
Use the -g flag of open, which avoids bringing the app to the foreground.
$ open -g /Applications/TextEdit.app
$
open will start the app, and then return to the command prompt.
After you run the program hit ctrl+z and type bg. You will return to your terminal CLI.
Whenever you want to go back to your program, just type fg.
You can background the job. In the Bash shell, this is done with the &. For example:
some_script_or_application &
Note that some daemons and processes background themselves. For example, on OS X, running open some.pdf will preview the PDF in a GUI while returning the command prompt immediately without needing to do anything special.
See the GNU Bash Manual for more on job control for background jobs.
I am trying to use Sublime Text + GoSublime to do Golang development.
I am working with a webserver in Go (ListenAndServe("8000", &handler)).
The problem I have is that when I run the Go process (while another one is running), the second process doesn't work (since the port is already in use).
What I want to happen is that when I go run web.go, if one was already running, shut that down before running this one.
Sublime Text 3's build system doesn't seem to keep track of the previous execution - so I don't know the best way to terminate. When I run CTRL+B it doesn't block, it executes the build system in another thread - meaning that I can't CTRL+C before executing the next. So what I'm having to do is terminate via the command line the existing process before starting the next one.
So I'm looking for either a solution with Sublime Text's build system configuration, or perhaps even having the Go process itself check to see if one is running and killing the process.
Ideas? It's sort of annoying to swap back and forth from terminal.
Not sure if I understand the question right.
But in sublime text build console, there is tskill command which can kill active tasks initiated from the console. So you can type Ctrl+B to invoke out console and type tskill to kill the running web.go task. There are also other alias tskill <task ID>, task replay or task go. Reference is here. After that you can run other commands including go run.
What's more there is a replay command. "It is like run but attempts to cancel any active executions before running". I feel it looks like what you want.
Further, Gosublime command shell has sh command mode. It's much flexible for example type sh killall web;go run web.go or run a shell script to run that.
Hopefully it helps.
I want to create my own personal logfile that logs not only when I log in and out, but also when I lock/unlock my screen. Kindof like /var/log/wtmp on steroids.
To do this, I decided to run a script when I log into Ubuntu that runs in the background until I quit. My plan to do this is to add the script to .bashrc, using ./startlogging.sh & and in the script I will use trap to catch signals. That's great, except .bashrc gets run every time I open a new terminal, which is not what I want for the logger.
Is there a way to tell in Bash that the current login is a gnome login? Alternatively, is there some sort of .gnomerc I can use to run my script?
Edit: Here is my script:
Edit 2: Removed the script, since it's not related to the question. I will repost my other question, rather than repurpose this one.
Are you looking for a way to detect what type of terminal it is?
Try:
echo $TERM
From Wikipedia:
TERM (Unix-like) - specifies the type of computer terminal or terminal
emulator being used (e.g., vt100 or dumb).
See also: List of Terminal Emulators
for bash use : ~/.bash_logout
that will get executed when you logout, which sounds like what you are trying to do.
Well, for just bash, what you want are .bash_login/.bash_logout in your home directory (rather than .bashrc) These are run whenever a LOGIN shell starts/finishes, which happens any time you log in to a shell (on a tty or console, or via ssh or other network login). These are NOT run for bash processes created to run in terminal windows that you create (as those are not login shells) so won't get run any time you open a new terminal.
The problem is that if you log in with some mechanism that does not involve a terminal (such as gdm running on the console to start a gnome or kde or unity session), then there's no login shell so .bash_login/logout never get run. For that case, the easiest is probably to put something in your .xsessionrc, which will get run every time you start an X session (which happens for any of those GUI environments, regardless of which one you run). Unfortunately, there's no standard script that runs when an X session finishes.
I'm writing a ksh script and I have to run a executable at a separate Command Prompt window.
xdg-open is a similar command line app in linux.
see https://superuser.com/questions/38984/linux-equivalent-command-for-open-command-on-mac-windows for details on its use.
I believe you mean something like xterm -e your.sh &
Don't forget the final &
maybe it´s not a seperate window that gets started, but you can run some executables in background using "&"
e.g.
./myexecutable &
means your script will not wait until myexecutable has finished but goes on immediately. maybe this is what you are looking for.
regards
xdg-open is a good equivalent for the MS windows commandline start command:
xdg-open file
opens that file or url with its default application
xdg-open .
opens the currect folder in the default file manager
One of the most useful terminal session programs is screen.
screen -dmS title executable
You can list all your screen sessions by running
screen -ls
And you can connect to your created screen session (also allowing multiple simultaneous/synchronized sessions) by running
screen -x title
This will open up the emulated terminal in the current window where executable is running. You can detach a screen session by pressing C-a C-d, and can reattach as many times as you wish.
If you really want your program started in a new terminal window, you could do something like this:
xterm yourtextmodeprogram
or
gnome-terminal -e yourtextmodeprogram
or
konsole -e mc
Trouble is that you cannot count on a particular terminal emulator being installed, so (again: if you really want to do this) you would need to look for the common ones and then execute the first one encountered.
As Joachim mentioned: The normal way to do this is to background the command (read about shell job control somewhere, if you want to dig deeper).
There are also cases where you want to start a persistent shell, i.e. a shell session which lives on when you close the terminal window. There are two ways to do this:
batch-oriented: nohup command-to-run &
interactive: screen
if you want a new windows, just start a new instance of your terminal application: in kde it's
konsole -e whatever
i'm sure the Gnome terminal has similar options
Some have recommended starting it in the background with &, but beware that that will still send all console output from the application you launch to the terminal you launched it from. Additionally, if you close the initial terminal the program you loaded will end.
If you're using a desktop environment like KDE or GNOME, I'd check the alt+f2 launching apps (gnome-open is the one for GNOME, I don't know the name of the KDE app) and see if you can pass them the command to launch as an argument.
Also, if your intention is to launch a daemon, you should check the nohup documentation.
I used nohup as the following command and it works:
nohup <your command> &
then press enter and enter!
don't forget the last &
for example, I ran a python code listening to port 5000:
nohup python3 -W ignore mycode.py &
then I made sure of running by netstat -tulnp | grep :5000 and it was ok.