I'm having difficulty launching a simple applescript choice list from a shell script. I have no issue launching dialog boxes to capture user input in the same way within my shell script. For whatever reason, the command below works inconsistently, the first call always times out. Subsequent calls with the same syntax sometimes work, sometimes don't. I get the same behavior when I run the command independent of the script within a bash shell - first execution times out, subsequent runs eventually work and display the choose list. It's driving me nuts, what am I missing! Thanks!
osascript -e 'Tell application "System Events" to return choose from list {"Students", "Faculty-Staff"}'
choose from list is part of Standard Additions. It's not related to System Events
osascript -e 'return choose from list {"Students", "Faculty-Staff"}'
Related
I have a shell running in a Vte.Terminal widget (could be bash, zsh, or any other interactive shell), I would like to monitor it so as to know when the prompt is available and a new command can be started.
I can't seem to come up with a consistent method.
Here are the ideas I've thought of so far:
Monitor for child process exit.
Could work some of the time, but commands that use only built-ins wouldn't spawn a child. (example: "while true; do; echo test; done;") Also When a command is started in background the prompt would be available before the child exited.
Watch for prompt string in Vte output.
Two problems: 1. A simple prompt string such as "#>" could easily be outputted by some script and give a false positive. 2. Knowing what the prompt string is, is problematic.
Any other ideas or a way to get one of the above working?
What my purpose is.
I'm working on a terminal emulator and would like to change the icon based on whether the prompt is available. Also I am attempting to allow commands to be 'queued' to run when next possible.
I have seen tools to daemonize processes.
But I have seen that:
some_command &
Runs process in a daemonized way, is this way bad? how is this way called?
Update
My doubt is that I am calling that command inside an ssh session, will the process last after closing ssh session?
That's not daemonized, that's simply running it as a background process.
A true dameon is a lot more involved; see e.g. http://en.wikipedia.org/wiki/Daemon_(computer_software)#Creation.
The & is an important little character in UNIX; it means "run the command in the background"; i.e., detach it from the window it was started from, so it does not block the command line.
Should the program ever try to read from the terminal window, it will be suspended, until the user "brings it to the foreground"; i.e., brings it to the state it would have had without the & to begin with.
To bring a program to the foreground, use "fg" or "%". If you have more than one background job to choose from ("jobs" will show you), then use for example "%2" to choose the second one.
Important:
If you forget to give the & at the end of line, and the process blocks the command input to the terminal window, you can put the process in the background "after the fact", by using Ctrl-Z. The process is suspended, and you get the command prompt back. The first thing you should do then is probably to give the command "bg", that resumes the process, but now in the background.
http://www.astro.ku.dk/comp-phys/tutorials/background.shtml
I have a VBScript I am working on that uses another object.
Sometimes that Object will get stuck. My VBScript code will hang on that line until it's "done". When it times out, I want to send the .Close command to the Object before the VBScript closes.
How can I tell when my VBScript times out?
I know that I can put WScript.Timeout = 60
Maybe something like..
WScript.Timeout = 5
do while true
loop
sub WScript_timeout()
msgbox("OK")
end sub
By setting the Timeout property you instruct the interpreter to automatically terminate the script when the timer expires. This is the same as running the interpreter with the option //T:xx and can't be caught/handled from within the script. What you want requires the ability to run code asynchronously, and VBScript doesn't really support that.
The real answer (to the question "How can I tell when my VBScript times out?") is that you can't. In common with almost all scripts, if VBScript stops running (because it's timed-out) the running thread ceases to run, so it can't report its status.
But there is a solution. However, it requires some cunning.
If you run a batch script instead, wherever you use that script to launch a new batch script (e.g. batch_1.bat includes this line: CALL batch_2.bat), the 2nd script will run, but the 1st script will wait.
Processing of the 1st script sits and waits (at the CALL) until script 2 stops running: at that point, control is returned to script 1, which continues with any code following the CALL, code which might be used to report the fact that script 2 has ended -
CALL batch_2.bat
ECHO The batch_2.bat script has stopped running && cmd /k
There are ways of launching batch_2.bat without causing batch_1.bat to pause until the 2nd script has finished, but they are not relevent here.
Theoretically, a batch script doesn't support parallel processing. VBScript certainly doesn't either. But the foregoing technique shows one method whereby parallel processing can be achieved, after a fashion, in a batch script -- which makes it one-up on vbScript!
.
One way to be certain that vbScript will time out, if the script hangs, so that the script must either complete successfully or fail (so you are never left with a frozen script due to it "hanging"), is to use a WScript function in your .vbs file and set the Windows Script Host settings to time out after (say) 30 seconds -
A. Open the "Windows Script Host Settings" dialog box:
Go to: Start > Run
In the "Open" box, type: WSCRIPT
Click "OK".
B. Set a timeout, to occur whenever WSH runs:
Select the option: "Stop script after specified
number of seconds".
In the "seconds" box, type the time limit to be
applied to all scripts (default is 10 seconds).
.
Here's a function to find and show what the current WSH/WScript timeout setting is (and if it shows that this setting hasn't been set yet, set it) -
WScript.Echo("WSH timeout: " + WScript.Timeout);
.
The option //T:xx can't be used, because it's a CScript function, which doesn't work in WScript, so can't be used in a .vbs vbScript file.
.
There is an screensaver that will launch scripts in OS X - which is great, but the problem I am having is that it launches multiple copies of the script. Is there a simple way to ensure that only one copy of this script is running at a time?
John Gruber wrote a post on something very similar to this a while back. Long story short, you would just wrap the entire thing in a block similar to the following:
tell application "System Events"
count (every process whose name is "BBEdit")
end tell
replacing "BBEdit" with your app name, and then launch only if the count is 0.
I have bash script I am running from powershell in windows that does a for loop. Every once in a while, one of the loop iteration hangs until I hit enter on the keyboard.
This doesn't happen all the time, in fact, it happens pretty rarely, but it still does.
The interesting thing is that my loop innards is basically time _command_ and so after I hit enter, it'll tell me how long the command took to run. The command actually takes way less time to execute than the loop iteration takes - because it's waiting for keyboard input for some odd reason.
It's pretty annoying to leave a script running overnight and come back in the morning to see that it didn't get very far.
Does someone knows WHY this happens and WHAT to do to get around it?
Thanks,
jbu
I have encountered the same problem several times. Now I guess I have found the reason!
If you ever press the mouse within the powershell, it might get stuck and need user to press "enter" to continue. So the get-around-way is to make sure that you didn't accidentally press your mouse within the shell window while you are already running some program...
Goto the powershell properties and unselect 'Quick Edit'/'Insert' check boxes. If these are selected, the console pauses output and resumes only when an Enter key is pressed ( You can identify this by monitoring the console title bar- it will switch from "Administrator:Windows PowerShell" to "Select Administrator:Windows Powershell"
Until you post the script, there's little we can do to help.
However, in general, one of your commands probably returns a null once in a while as input to stdin of another command which, upon seeing null looks to the terminal as stdin. Or something along those lines.