I have observed in zsh if I run a command like,
some_command &
and close the terminal, it would kill the process started by some_command.
While it doesn't happen with bash.
So, I'm curious if the behaviour of putting "&" after command is shell specific?
Yes, the exact specifics on background vs detach from controlling terminal vs process group, etc are shell-specific. You should look up the nohup command for some additional detail.
Related
Where I would then be able to kill the running process with a kill -9 <id> command. It's annoying having a terminal window open that will run for a while.
Is there some command for this?
One that I could append to whatever command I'd like to run?
I feel like it's not an OS thing and more of a shell specific thing – where some shell command would include scripts that run in the background and others where they don't?
Restructured my questions and discovered the answer to my question in the suggested/related questions and discovered the nohup command and from the comments thanks to #RudyM the bg command
I feel sure this will end up as a duplicate, but I don't know how to word it so that I can search for it...
I like to do my programming in emacs, which I launch from the terminal. When I use my mac I use aquamacs and the command
aquamacs Program.py
will launch aquamacs in a separate window ready to edit Program.py. When I work on my linux machine however to get the same result I must type
emacs Program.py &
And I'm always forgetting the "&". So 70% of the time I end up closing the emacs window, and relaunching again with the "&". Now I understand why that "&" is there, but is there a way to set up my system so that the command
emacs Program.py
always launches as a detached process? The only time I might not want that behavior is if I was SSHing in over a slow connection, in which case I usually use "-nw" anyway.
You can click on the terminal and press Ctrl-Z to move an already running foreground process to the background.
Alternatively you could add this function to your ~/.bashrc:
emacs() {
command emacs "$#" &
}
For the specific case of emacs, I use a shell script, which is more complicated than this but for your purposes boils down to
#!/bin/csh -f
/bin/emacs $*:q &
Put it in a directory which is earlier in your $path than where the "real" emacs is, and replace /bin/emacs with the real path to emacs on your system.
This occurs when I set the vim's shell to be interactive:
set shellcmdflag=-ic
or
set shell=/bin/bash\ -i
I like these because they give syntax highlighting to the output (eg.: !ls)
But the cost is that I have to type fg # every time.
Is this a default behavior?
How can I get interactive shell in vim without having to make it run foreground?
You can't. This behavior is perfectly normal and expected and in line with Vim's author's philosophy. It's very unlikely to change in the future.
If you want a shell inside Vim, you'll have to install a plugin like Conque or Vimshell.
I usually just use tmux instead. You can split the terminal and have a normal interactive shell and an instance of vim running side by side - very handy.
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.
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.