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).
Related
If you start git-bash and monitor bash.exe with procmon, you will see that just running a simple command like clear starts a new instance of bash.exe. This instance doesn't stick around for the lifetime of the external command - it is started and almost immediately terminates. Thus if you type grep hello you will see that although the grep process is still running the additional bash.exe process terminates.
Is there a reason bash launches a new bash.exe process and is there any way to change this behaviour? It causes performance problems in certain environments were antivirus software is checking every process that starts: one more process is another half-second delay.
I run calculations on Windows for hours and would like to have the calculation report/log inside the interactive IDLE/shell window be saved to a file at the end by a command.
Would be nice to exit() and close the window too.
As much as I like Linux, this is an Unattended Windows machine, hence, some modules/commands are not available, sadly, and the ability to install other software is limited.
The fact that the developers did not think of a command to save the transactions within the IDLE/shell is surprising.
I know in some environments you can direct the output of a job, like a report to another text file by using the key -o, --o, --output, > to a text file. Surprisingly Python does not support anything like that!
Any help would be appreciated
Thanks
Windows Command Prompt supports stdout redirection and probably stderr redirection. I just tested python -c "print(test)" > F:/dev/tem/out.txt and the print out went to out.txt. Replace -c "print('test') with script.py and the same should happen. Piping stdout of one program to stdin of another might work. You might be able to chain programs with a .bat file. PowerShell likely is more powerful and flexible, but I have never used it.
I am not completely clear on what you are asking, but I hope the following answers your questions.
Python runs in 2 modes: batch and interactive. Interactive mode is intended for ephermeral interaction with a human. Batch mode is for unattended computation, with occasional screen messages, but with most results sent to a file other than the screen. Both modes are combined when you run python -i xyz.py. The file is first run in batch mode, and then Python shifts to interactive mode.
It sounds like you should be using batch mode rather than either Python's or IDLE's interactive mode. If your code runs from IDLE, you should be able to run it directly with the same python.exe that you used to run IDLE. There are exceptions, of course, if one makes one's code dependent on running within IDLE, but this is unlikely to be an accident or to be needed for unattended running.
The IDLE Shell simulates interactive Python. When a file is run from an editor window, IDLE simulates python -i file-being-edited.py, with screen output going to Shell. In either case, an interactive user can save the contents of Shell with the File => Save As menu command. So there is such a command. There are also close window and exit commands and shortcuts.
In IDLE's intended use, as an interactive python learning and program development environment, there is no need from for a program to issue these commands. To save data in a file, a program can open a file and write data directly.
Try to see if you can install Jupyter Notebook (not separate software, but just a python module)
pip install jupyter
Jupyter notebook is highly helpful for saving and sharing your code. It can be used as both a shell and as a script editor.
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 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.