how to assign a function with arguments to a variable, then pass the variable to another function in shell...












0















I'm new to shell script, so any information is not trivial at all.
I'm writing a generic function create_dir that take a variable $dirname and an option variable $function to generate a directory. If the optional $function is absent, the default function is mkdir. Like this:



File ~/bin/lib/create_dir.sh:



#!/bin/bash



create_dir()

{

    DIRNAME=$1

    FUNCTION=${2:-mkdir}

    $FUNCTION $DIRNAME

}

export -f create_dir


That works fine.



Now I import this into another file ~/bin/create_app



#!/bin/bash

. "${HOME}/bin/lib/create_dir.sh"



DIRNAME=$1

FUNCTION="python manage.py startapp"



create_dir $FUNCTION $DIRNAME


When I run create_app it imported the create_dir but the variable $FUNCTION it feeds the create_dir is wrong. The variable $FUNCTION has only one word python instead of python manage.py startapp as I wanted.



Why? How to fix it?






command-line bash scripts







share|improve this question


















  • 1





    You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run create_dir python manage.py startapp ... followed by all the words in the first argument to create_app. This way the first argument will be python and the second one manage.py

    – Stefan Hamcke
    Feb 1 at 19:33













  • Stefan is right. Important rule in shell programming: When in doubt: quote. To check your scripts you can use shellcheck

    – Ralf
    Feb 1 at 19:39













  • oh my god I saw somewhere they emphasized the importance of putting variables between double quotes. Now I seee

    – Linh Chi Nguyen
    Feb 1 at 19:39
















0















I'm new to shell script, so any information is not trivial at all.
I'm writing a generic function create_dir that take a variable $dirname and an option variable $function to generate a directory. If the optional $function is absent, the default function is mkdir. Like this:



File ~/bin/lib/create_dir.sh:



#!/bin/bash



create_dir()

{

    DIRNAME=$1

    FUNCTION=${2:-mkdir}

    $FUNCTION $DIRNAME

}

export -f create_dir


That works fine.



Now I import this into another file ~/bin/create_app



#!/bin/bash

. "${HOME}/bin/lib/create_dir.sh"



DIRNAME=$1

FUNCTION="python manage.py startapp"



create_dir $FUNCTION $DIRNAME


When I run create_app it imported the create_dir but the variable $FUNCTION it feeds the create_dir is wrong. The variable $FUNCTION has only one word python instead of python manage.py startapp as I wanted.



Why? How to fix it?






command-line bash scripts







share|improve this question


















  • 1





    You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run create_dir python manage.py startapp ... followed by all the words in the first argument to create_app. This way the first argument will be python and the second one manage.py

    – Stefan Hamcke
    Feb 1 at 19:33













  • Stefan is right. Important rule in shell programming: When in doubt: quote. To check your scripts you can use shellcheck

    – Ralf
    Feb 1 at 19:39













  • oh my god I saw somewhere they emphasized the importance of putting variables between double quotes. Now I seee

    – Linh Chi Nguyen
    Feb 1 at 19:39














0












0








0








I'm new to shell script, so any information is not trivial at all.
I'm writing a generic function create_dir that take a variable $dirname and an option variable $function to generate a directory. If the optional $function is absent, the default function is mkdir. Like this:



File ~/bin/lib/create_dir.sh:



#!/bin/bash



create_dir()

{

    DIRNAME=$1

    FUNCTION=${2:-mkdir}

    $FUNCTION $DIRNAME

}

export -f create_dir


That works fine.



Now I import this into another file ~/bin/create_app



#!/bin/bash

. "${HOME}/bin/lib/create_dir.sh"



DIRNAME=$1

FUNCTION="python manage.py startapp"



create_dir $FUNCTION $DIRNAME


When I run create_app it imported the create_dir but the variable $FUNCTION it feeds the create_dir is wrong. The variable $FUNCTION has only one word python instead of python manage.py startapp as I wanted.



Why? How to fix it?






command-line bash scripts







share|improve this question














I'm new to shell script, so any information is not trivial at all.
I'm writing a generic function create_dir that take a variable $dirname and an option variable $function to generate a directory. If the optional $function is absent, the default function is mkdir. Like this:



File ~/bin/lib/create_dir.sh:



#!/bin/bash



create_dir()

{

    DIRNAME=$1

    FUNCTION=${2:-mkdir}

    $FUNCTION $DIRNAME

}

export -f create_dir


That works fine.



Now I import this into another file ~/bin/create_app



#!/bin/bash

. "${HOME}/bin/lib/create_dir.sh"



DIRNAME=$1

FUNCTION="python manage.py startapp"



create_dir $FUNCTION $DIRNAME


When I run create_app it imported the create_dir but the variable $FUNCTION it feeds the create_dir is wrong. The variable $FUNCTION has only one word python instead of python manage.py startapp as I wanted.



Why? How to fix it?






command-line bash scripts




command-line bash scripts






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Feb 1 at 19:30









Linh Chi NguyenLinh Chi Nguyen

63




63








  • 1





    You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run create_dir python manage.py startapp ... followed by all the words in the first argument to create_app. This way the first argument will be python and the second one manage.py

    – Stefan Hamcke
    Feb 1 at 19:33













  • Stefan is right. Important rule in shell programming: When in doubt: quote. To check your scripts you can use shellcheck

    – Ralf
    Feb 1 at 19:39













  • oh my god I saw somewhere they emphasized the importance of putting variables between double quotes. Now I seee

    – Linh Chi Nguyen
    Feb 1 at 19:39














  • 1





    You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run create_dir python manage.py startapp ... followed by all the words in the first argument to create_app. This way the first argument will be python and the second one manage.py

    – Stefan Hamcke
    Feb 1 at 19:33













  • Stefan is right. Important rule in shell programming: When in doubt: quote. To check your scripts you can use shellcheck

    – Ralf
    Feb 1 at 19:39













  • oh my god I saw somewhere they emphasized the importance of putting variables between double quotes. Now I seee

    – Linh Chi Nguyen
    Feb 1 at 19:39








1




1





You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run create_dir python manage.py startapp ... followed by all the words in the first argument to create_app. This way the first argument will be python and the second one manage.py

– Stefan Hamcke
Feb 1 at 19:33







You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run create_dir python manage.py startapp ... followed by all the words in the first argument to create_app. This way the first argument will be python and the second one manage.py

– Stefan Hamcke
Feb 1 at 19:33















Stefan is right. Important rule in shell programming: When in doubt: quote. To check your scripts you can use shellcheck

– Ralf
Feb 1 at 19:39







Stefan is right. Important rule in shell programming: When in doubt: quote. To check your scripts you can use shellcheck

– Ralf
Feb 1 at 19:39















oh my god I saw somewhere they emphasized the importance of putting variables between double quotes. Now I seee

– Linh Chi Nguyen
Feb 1 at 19:39





oh my god I saw somewhere they emphasized the importance of putting variables between double quotes. Now I seee

– Linh Chi Nguyen
Feb 1 at 19:39










1 Answer
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You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run 



create_dir python manage.py startapp ...


followed by all the words in the first argument to create_app. This way the first argument to create_dir will be python and the second one manage.py.



You are always on the safe side if you put double quotes around your variable expansions. This will prevent the shell from splitting the value of that variable into separate words, which the function then regards as different arguments when you pass to it that variable as an argument.



There are cases where you can go without quotes, for example in the line



DIRNAME=$1


or more generally



var2=$var


as the bash will automatically assume that you want to assign the entire value of var to the variable var2. On the other hand, if you write the value directly, you need to use quotes:



string="Hello World"





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    0














    You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run 



    create_dir python manage.py startapp ...


    followed by all the words in the first argument to create_app. This way the first argument to create_dir will be python and the second one manage.py.



    You are always on the safe side if you put double quotes around your variable expansions. This will prevent the shell from splitting the value of that variable into separate words, which the function then regards as different arguments when you pass to it that variable as an argument.



    There are cases where you can go without quotes, for example in the line



    DIRNAME=$1


    or more generally



    var2=$var


    as the bash will automatically assume that you want to assign the entire value of var to the variable var2. On the other hand, if you write the value directly, you need to use quotes:



    string="Hello World"





    share|improve this answer






























      0














      You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run 



      create_dir python manage.py startapp ...


      followed by all the words in the first argument to create_app. This way the first argument to create_dir will be python and the second one manage.py.



      You are always on the safe side if you put double quotes around your variable expansions. This will prevent the shell from splitting the value of that variable into separate words, which the function then regards as different arguments when you pass to it that variable as an argument.



      There are cases where you can go without quotes, for example in the line



      DIRNAME=$1


      or more generally



      var2=$var


      as the bash will automatically assume that you want to assign the entire value of var to the variable var2. On the other hand, if you write the value directly, you need to use quotes:



      string="Hello World"





      share|improve this answer




























        0












        0








        0







        You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run 



        create_dir python manage.py startapp ...


        followed by all the words in the first argument to create_app. This way the first argument to create_dir will be python and the second one manage.py.



        You are always on the safe side if you put double quotes around your variable expansions. This will prevent the shell from splitting the value of that variable into separate words, which the function then regards as different arguments when you pass to it that variable as an argument.



        There are cases where you can go without quotes, for example in the line



        DIRNAME=$1


        or more generally



        var2=$var


        as the bash will automatically assume that you want to assign the entire value of var to the variable var2. On the other hand, if you write the value directly, you need to use quotes:



        string="Hello World"





        share|improve this answer















        You should quote the argument like this: "$FUNCTION". Otherwise, the shell will run 



        create_dir python manage.py startapp ...


        followed by all the words in the first argument to create_app. This way the first argument to create_dir will be python and the second one manage.py.



        You are always on the safe side if you put double quotes around your variable expansions. This will prevent the shell from splitting the value of that variable into separate words, which the function then regards as different arguments when you pass to it that variable as an argument.



        There are cases where you can go without quotes, for example in the line



        DIRNAME=$1


        or more generally



        var2=$var


        as the bash will automatically assume that you want to assign the entire value of var to the variable var2. On the other hand, if you write the value directly, you need to use quotes:



        string="Hello World"






        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Feb 1 at 20:03

























        answered Feb 1 at 19:49









        Stefan HamckeStefan Hamcke

        4851622




        4851622






























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