I want to do one very simple thing. Every time I run a command on my VS Code terminal (I'm running small JS programs using node.js), I want to store the output to a text file. Something like this
node ./test_script.js > test_script.txt
Doing this just works. But there are many times I just forget to add the > test_script.txt part while quickly using the terminal. Is there any way to make that part happen by default?
It should automatically get appended to the terminal input if I run node ./test_script.js. I also want the output file to be named the same as the .js file but with .txt extension, so it is dynamically named.
If yes, what is that setting connected to? Is it a VS Code setting, a node.js setting, or a terminal setting? Will it work if I am running a python script as well?
Thanks!
Related
I am currently running a python3 script in Ubuntu server 18.04. When i type new commands into the command line it just prints the commands. My terminal window looks like this:
mitch#server:`$ cd /home/mitch/folder
mitch#server:`/folder$ python3 main.py
file running ...
text i input just shows like this
I need to keep the script running and run other commands, how do i navigate back to:
mitch#server:`
I'm new to servers/Ubuntu/commands so this may seem trivial! Thank you
So you can't "navigate" back to that, since you're technically already there, you're just running a script in your shell which is occupying your shell - think of it like you opened a program in full screen.
But you have a few options:
The most basic is to run the script in the 'background' this is a simple as adding a & to the end of your command (note that it will still send any message from the script into your terminal - if your script is programmed to send messages that is).
Another option is to use a terminal multiplex like which lets you have multiple terminals open, as well as split screen terminals and many other features. One of the more popular multiplexers is called tmux, just keep in mind that it does have a bit of a learning curve to it, but is extremely useful once you learn it.
I just started learning Node.js and I have the following question:
Is there an easy way to check variable, array, etc., values in the node.js command prompt or shell? For example, when writing normal javascript, I am used to opening up the browser's console where I can just type in the name of a variable to see its value.
How would I do this same thing when writing code in node.js? I know I can open the shell and write javascript, and then type in variable names and it will return their values, but how can I do this on the fly, as I'm writing an app?
Alright, I've figured this out...
Just as in front-end javascript development, you can input 'debugger;' into your .js file where you want to begin debugging. Then, from your command prompt, you would type:
node --inspect-brk [filename] [anything else required to call the function]
After this, open a tab in Chrome and type 'chrome://inspect' You should then see a link that reads 'Open dedicated DevTools for Node.' When you click this, you will be able to debug the program from Chrome, just as you normally would when working on browser-based programs. This works with nodemon as well, and you can leave this window open while working, no need to close/open for different files, etc.
Hope this helps someone else who is also new to Node!
When running an interactive session, PyCharm thinks of os.getcwd() as my project's directory. However, when I run my script from the command line, PyCharm thinks of os.getcwd() as the directory of the script.
Is there a good workaround for this? Here is what I tried and did not like:
going to Run/Edit Configurations and changing the working directory manually. I did not like this solution, because I will have to do it for every script that I run.
having one line in my code that "fixes" the path for the purposes of interactive sessions and commenting it out before running from command line. This works, but feels wrong.
Is there a way to do this or is it just the way it is supposed to be? Maybe I shouldn't be trying to run random scripts within my project?
Any insight would be greatly appreciated.
Clarification:
By "interactive session" I mean being able to run each line individually in a Python/IPython Console
By "running from command line" I mean creating a script my_script.py and running python path_to_myscript/my_script.py (I actually press the Run button at PyCharm, but I think it's the same).
Other facts that might prove worth mentioning:
I have created a PyCharm project. This contains (among other things) the package Graphs, which contains the module Graph and some .txt files. When I do something within my Graph module (e.g. read a graph from a file), I like to test that things worked as expected. I do this by running a selection of lines (interactively). To read a .txt file, I have to go (using os.path.join()) from the current working directory (the project directory, ...\\project_name) to the module's directory ...\\project_name\\Graphs, where the file is located. However, when I run the whole script via the command line, the command reading the .txt file raises an Error, complaining that no file was found. By looking on the name of the file that was not found, I see that the full file name is something like this:
...\\project_name\\Graphs\\Graphs\\graph1.txt
It seems that this time the current working directory is ...\\project_name\\Graphs\\, and my os.path.join() command actually spoils it.
I user various methods in my python scripts.
set the working directory as first step of your code using os.chdir(some_existing_path)
This would mean all your other paths should be referenced to this, as you hard set the path. You just need to make sure it works from any location and your specifically in your IDE. Obviously, another os.chdir() would change the working directory and os.getcwd() would return the new working directory
set the working directory to __file__ by using os.chdir(os.path.dirname(__file__))
This is actually what I use most, as it is quite reliable, and then I reference all further paths or file operations to this. Or you can simply refer to as os.path.dirname(__file__) in your code without actually changing the working directory
get the working directory using os.getcwd()
And reference all path and file operations to this, knowing it will change based on how the script is launched. Note: do NOT assume that this returns the location of your script, it returns the working directory of the shell !!
[EDIT based on new information]
By "interactive session" I mean being able to run each line
individually in a Python/IPython Console
By running interactively line-by-line in a Python console, the __file__ is not defined, afterall: you are not executing a file. Hence you cannot use os.path.dirname(__file__) you will have to use something like os.chdir(some_known_existing_dir) to reference a path. As a programmer you need to be very aware of working directory and changes to this, your code should reflect that.
By "running from command line" I mean creating a script my_script.py
and running python path_to_myscript/my_script.py (I actually press the
Run button at PyCharm, but I think it's the same).
This, both executing a .py from command line as well as running in your IDE, will populate the __file__, hence you can use os.path.dirname(__file__)
HTH
I am purposely adding another answer to this post, in regards the following:
Other facts that might prove worth mentioning:
I have created a PyCharm project. This contains (among other things)
the package Graphs, which contains the module Graph and some .txt
files. When I do something within my Graph module (e.g. read a graph
from a file), I like to test that things worked as expected. I do this
by running a selection of lines (interactively). To read a .txt file,
I have to go (using os.path.join()) from the current working directory
(the project directory, ...\project_name) to the module's directory
...\project_name\Graphs, where the file is located. However, when I
run the whole script via the command line, the command reading the
.txt file raises an Error, complaining that no file was found. By
looking on the name of the file that was not found, I see that the
full file name is something like this:
...\project_name\Graphs\Graphs\graph1.txt It seems that this time
the current working directory is ...\project_name\Graphs\, and my
os.path.join() command actually spoils it.
I strongly believe that if a python script takes input from any file, that the author of the script needs to cater for this in the script.
What I mean is you as the author need to make sure you know the following regardless of how your script is executed:
What is the working directory
What is the script directory
These two you have no control over when you hand off your script to others, or run it on other peoples machines. The working directory is dependent on how the script is launched. It seems that you run on Windows, so here is an example:
C:\> c:\python\python your_script.py
The working directory is now C:\ if your_script.py is in C:\
C:\some_dir\another_dir\> c:\python\python.exe c:\your_script_dir\your_script.py
The working directory is now C:\some_dir\another_dir
And the above example may even give different results if the SYSTEM PATH variable is set to the path of the location of your_script.py
You need to ensure that your script works even if the user(s) of your script are placing this in various locations on their machines. Some people (and I don't know why) tend to put everything on the Desktop. You need to ensure your script can cope with this, including any spaces in the path name.
Furthermore, if your script is taking input from a file, the you as the author need to ensure that you can cope with changes in working directory, and changes of script directory. There are a few things you may consider:
Have your script input from a known (static) directory, something like C:\python_input\
Have your script input from a known (configurable) directory, use ConfigParser, you can search here on stackoverflow on many posts
Have your script input from a known directory related to the location of the script (using os.path.dirname(__file__))
any other method you may employ to ensure your script can get to the input
Ultimately this is all in your control, and you need to code to ensure it is working.
HTH,
Edwin.
I am writing a program that handles some data on a server. Throughout the program, many files are made and sent as input into other programs. To do this, I usually make the command string, then run it like so:
cmd = "prog input_file1 input_file2 > outputfile"
os.system(cmd)
When I run the command, however, the programs being called report that they cannot open the files. If I run the python code on my local computer, it is fine. When I loaded it onto the server, it started to fail. I think this is related to issues with permissions, but am not sure how I can fix this. Many of the files, particularly the output files, are being created at run time. The input files have full permissions for all users. Any help or advice would be appreciated!
Cheers!
The python code you list is simple and correct, so the problem is likely not in the two lines of your example. Here are some related areas for you to check out.
Permissions
The user running the python script must have the appropriate permission (read, write, execute). I see from comments that you've already checked this.
What command are you running
If the command is literally typed into your source code like in the example, then you know what command is being run, but if you are generating any part of it (eg. the list of operands, the name of the output file, other parameters, etc), make sure there are no bugs in the portions of your code that generate the command. For example before the call to os.system(cmd) consider including a line like print("About to execute: " + cmd) so you can see exactly what will be run.
Directly invoke the command
If all the above looks good, try to execute the command directly at a terminal on your server. What output do you get then. It's possible that the problem is with the underlying command itself rather than your python code.
I just ran a script on a server that generates a lot of output on the command window.
However, now, after running it for roughly 4 hours I want to check all the output, but the beginning of the output has already disappeared from the terminal window. When I scroll up, it is not there anymore.
Is there any way to access this? It needs to be via commands in the terminal because I'm running it on a server.
Thanks.
Best way is to redirect the output to a file & open the file to check for all the output.
You can also redirect the script by running it in background & saving the output to a file. Do let me know what type of command you are running for which I can give you the exact command. :)
if it's a real terminal and not a virtual terminal
you need to recompile your kernel and increase the buffer size of your terminal.
in the .config file of your kernel the parameter you need to increase is
CONFIG_VGACON_SOFT_SCROLLBACK_SIZE
Actually, redirecting I/O interferes with many programs (for instance, changing the output from a tty to a plain file). Use the script program to capture all output from programs run in a shell, with minimal interference.