Use subprocess in python to echo a variable

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I have a variable in python, and I'm trying to open a subprocess and echo the variable, then create a file with the variable in it.
I tried this:



subprocess.Popen(['echo "$var" > file.txt'], shell=True)


It creates the file, but it's empty. How can I get the result that I want?






linux shell-script python echo







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    Not sure of your use case, but it might be easier and more robust to open the file, format the variable appropriately into a string, and write the string to the file.
    – Mark Plotnick
    1 hour ago














up vote
0
down vote

favorite












I have a variable in python, and I'm trying to open a subprocess and echo the variable, then create a file with the variable in it.
I tried this:



subprocess.Popen(['echo "$var" > file.txt'], shell=True)


It creates the file, but it's empty. How can I get the result that I want?






linux shell-script python echo







share|improve this question









New contributor




david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.















  • 1




    Not sure of your use case, but it might be easier and more robust to open the file, format the variable appropriately into a string, and write the string to the file.
    – Mark Plotnick
    1 hour ago












up vote
0
down vote

favorite









up vote
0
down vote

favorite











I have a variable in python, and I'm trying to open a subprocess and echo the variable, then create a file with the variable in it.
I tried this:



subprocess.Popen(['echo "$var" > file.txt'], shell=True)


It creates the file, but it's empty. How can I get the result that I want?






linux shell-script python echo







share|improve this question









New contributor




david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











I have a variable in python, and I'm trying to open a subprocess and echo the variable, then create a file with the variable in it.
I tried this:



subprocess.Popen(['echo "$var" > file.txt'], shell=True)


It creates the file, but it's empty. How can I get the result that I want?






linux shell-script python echo




linux shell-script python echo






share|improve this question









New contributor




david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









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david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









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edited 12 mins ago









mrc02_kr

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asked 2 hours ago









david

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david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






david is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 1




    Not sure of your use case, but it might be easier and more robust to open the file, format the variable appropriately into a string, and write the string to the file.
    – Mark Plotnick
    1 hour ago












  • 1




    Not sure of your use case, but it might be easier and more robust to open the file, format the variable appropriately into a string, and write the string to the file.
    – Mark Plotnick
    1 hour ago







1




1




Not sure of your use case, but it might be easier and more robust to open the file, format the variable appropriately into a string, and write the string to the file.
– Mark Plotnick
1 hour ago




Not sure of your use case, but it might be easier and more robust to open the file, format the variable appropriately into a string, and write the string to the file.
– Mark Plotnick
1 hour ago










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In Python you don't use $ sign to use a variable. Also when you want to embed variable into string, you cannot just simply use variable name in string. You should do something like that:



subprocess.Popen(['echo "" > file.txt'.format(var)], shell=True)


This is great website which will explain you how to use .format method.






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    up vote
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    down vote













    In Python you don't use $ sign to use a variable. Also when you want to embed variable into string, you cannot just simply use variable name in string. You should do something like that:



    subprocess.Popen(['echo "" > file.txt'.format(var)], shell=True)


    This is great website which will explain you how to use .format method.






    share|improve this answer
























      up vote
      0
      down vote













      In Python you don't use $ sign to use a variable. Also when you want to embed variable into string, you cannot just simply use variable name in string. You should do something like that:



      subprocess.Popen(['echo "" > file.txt'.format(var)], shell=True)


      This is great website which will explain you how to use .format method.






      share|improve this answer






















        up vote
        0
        down vote










        up vote
        0
        down vote









        In Python you don't use $ sign to use a variable. Also when you want to embed variable into string, you cannot just simply use variable name in string. You should do something like that:



        subprocess.Popen(['echo "" > file.txt'.format(var)], shell=True)


        This is great website which will explain you how to use .format method.






        share|improve this answer












        In Python you don't use $ sign to use a variable. Also when you want to embed variable into string, you cannot just simply use variable name in string. You should do something like that:



        subprocess.Popen(['echo "" > file.txt'.format(var)], shell=True)


        This is great website which will explain you how to use .format method.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 1 hour ago









        mrc02_kr

        1,037320




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