How am I allowed to pass a void parameter through bash functions?

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I'm writing something like the following script. It's doesn't work as expected because the function deleteCEfromCeLst has to call a script specifying to it a "void" parameter through the spawnPrg function, but if I specify in the spawnPrg function parameters the "void" parameter '', that I use when I call the script $HOME/execsh/delete.sh directly from prompt, this "void" parameter results (correctly) as nothing and not as a not specified parameter.



The use of the spawnPrg function is mandatory because it will be used from other functions called from the "main" flow or directly by the main flow, furthermore the function spawnPrg shall contain behaviours act to register something like a log file.



#!/bin/bash

spawnPrg()

echo $@
$@ &

return


deleteCEfromCeLst()

local d

cat ce.lst

deleteCEfromCeLst
exit


I tried also to code deleteCEfromCeLst as:



deleteCEfromCeLst()

local d

cat ce.lst


With the above code the result is that the function spawnPrg is executed as it is sent to the prompt as:



$HOME/execsh/delete.sh $1 '' $d


where the "void" parameter is specified as the string '' that is either that the second parameter sent to the delete.sh script is not a "void" parameter.










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    0















    I'm writing something like the following script. It's doesn't work as expected because the function deleteCEfromCeLst has to call a script specifying to it a "void" parameter through the spawnPrg function, but if I specify in the spawnPrg function parameters the "void" parameter '', that I use when I call the script $HOME/execsh/delete.sh directly from prompt, this "void" parameter results (correctly) as nothing and not as a not specified parameter.



    The use of the spawnPrg function is mandatory because it will be used from other functions called from the "main" flow or directly by the main flow, furthermore the function spawnPrg shall contain behaviours act to register something like a log file.



    #!/bin/bash

    spawnPrg()

    echo $@
    $@ &

    return


    deleteCEfromCeLst()

    local d

    cat ce.lst

    deleteCEfromCeLst
    exit


    I tried also to code deleteCEfromCeLst as:



    deleteCEfromCeLst()

    local d

    cat ce.lst


    With the above code the result is that the function spawnPrg is executed as it is sent to the prompt as:



    $HOME/execsh/delete.sh $1 '' $d


    where the "void" parameter is specified as the string '' that is either that the second parameter sent to the delete.sh script is not a "void" parameter.










    share|improve this question
























      0












      0








      0








      I'm writing something like the following script. It's doesn't work as expected because the function deleteCEfromCeLst has to call a script specifying to it a "void" parameter through the spawnPrg function, but if I specify in the spawnPrg function parameters the "void" parameter '', that I use when I call the script $HOME/execsh/delete.sh directly from prompt, this "void" parameter results (correctly) as nothing and not as a not specified parameter.



      The use of the spawnPrg function is mandatory because it will be used from other functions called from the "main" flow or directly by the main flow, furthermore the function spawnPrg shall contain behaviours act to register something like a log file.



      #!/bin/bash

      spawnPrg()

      echo $@
      $@ &

      return


      deleteCEfromCeLst()

      local d

      cat ce.lst

      deleteCEfromCeLst
      exit


      I tried also to code deleteCEfromCeLst as:



      deleteCEfromCeLst()

      local d

      cat ce.lst


      With the above code the result is that the function spawnPrg is executed as it is sent to the prompt as:



      $HOME/execsh/delete.sh $1 '' $d


      where the "void" parameter is specified as the string '' that is either that the second parameter sent to the delete.sh script is not a "void" parameter.










      share|improve this question














      I'm writing something like the following script. It's doesn't work as expected because the function deleteCEfromCeLst has to call a script specifying to it a "void" parameter through the spawnPrg function, but if I specify in the spawnPrg function parameters the "void" parameter '', that I use when I call the script $HOME/execsh/delete.sh directly from prompt, this "void" parameter results (correctly) as nothing and not as a not specified parameter.



      The use of the spawnPrg function is mandatory because it will be used from other functions called from the "main" flow or directly by the main flow, furthermore the function spawnPrg shall contain behaviours act to register something like a log file.



      #!/bin/bash

      spawnPrg()

      echo $@
      $@ &

      return


      deleteCEfromCeLst()

      local d

      cat ce.lst

      deleteCEfromCeLst
      exit


      I tried also to code deleteCEfromCeLst as:



      deleteCEfromCeLst()

      local d

      cat ce.lst


      With the above code the result is that the function spawnPrg is executed as it is sent to the prompt as:



      $HOME/execsh/delete.sh $1 '' $d


      where the "void" parameter is specified as the string '' that is either that the second parameter sent to the delete.sh script is not a "void" parameter.







      bash shell-script scripting bash-functions






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      share|improve this question











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      share|improve this question










      asked Feb 2 at 12:09









      Sir Jo BlackSir Jo Black

      1965




      1965




















          1 Answer
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          3














          Quote the variable expansions.



          If we have a script foo.sh:



          $ cat foo.sh 
          #!/bin/sh
          args()
          printf ">%s<n" "$@"

          args "$1" "" foo


          And we call it with sh foo.sh "", the output is:



          ><
          ><
          >foo<


          That is, one empty argument from "$1" (the argument to foo.sh), another from the hard-coded "" in the script, and then the fixed string foo.



          If either of $@ or $1 would have been unquoted, the empty values in question would disappear as part of word splitting.



          See:



          • This wiki page on word splitting: http://mywiki.wooledge.org/WordSplitting

          • Why does my shell script choke on whitespace or other special characters?

          • When is double-quoting necessary?





          share|improve this answer






















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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            3














            Quote the variable expansions.



            If we have a script foo.sh:



            $ cat foo.sh 
            #!/bin/sh
            args()
            printf ">%s<n" "$@"

            args "$1" "" foo


            And we call it with sh foo.sh "", the output is:



            ><
            ><
            >foo<


            That is, one empty argument from "$1" (the argument to foo.sh), another from the hard-coded "" in the script, and then the fixed string foo.



            If either of $@ or $1 would have been unquoted, the empty values in question would disappear as part of word splitting.



            See:



            • This wiki page on word splitting: http://mywiki.wooledge.org/WordSplitting

            • Why does my shell script choke on whitespace or other special characters?

            • When is double-quoting necessary?





            share|improve this answer



























              3














              Quote the variable expansions.



              If we have a script foo.sh:



              $ cat foo.sh 
              #!/bin/sh
              args()
              printf ">%s<n" "$@"

              args "$1" "" foo


              And we call it with sh foo.sh "", the output is:



              ><
              ><
              >foo<


              That is, one empty argument from "$1" (the argument to foo.sh), another from the hard-coded "" in the script, and then the fixed string foo.



              If either of $@ or $1 would have been unquoted, the empty values in question would disappear as part of word splitting.



              See:



              • This wiki page on word splitting: http://mywiki.wooledge.org/WordSplitting

              • Why does my shell script choke on whitespace or other special characters?

              • When is double-quoting necessary?





              share|improve this answer

























                3












                3








                3







                Quote the variable expansions.



                If we have a script foo.sh:



                $ cat foo.sh 
                #!/bin/sh
                args()
                printf ">%s<n" "$@"

                args "$1" "" foo


                And we call it with sh foo.sh "", the output is:



                ><
                ><
                >foo<


                That is, one empty argument from "$1" (the argument to foo.sh), another from the hard-coded "" in the script, and then the fixed string foo.



                If either of $@ or $1 would have been unquoted, the empty values in question would disappear as part of word splitting.



                See:



                • This wiki page on word splitting: http://mywiki.wooledge.org/WordSplitting

                • Why does my shell script choke on whitespace or other special characters?

                • When is double-quoting necessary?





                share|improve this answer













                Quote the variable expansions.



                If we have a script foo.sh:



                $ cat foo.sh 
                #!/bin/sh
                args()
                printf ">%s<n" "$@"

                args "$1" "" foo


                And we call it with sh foo.sh "", the output is:



                ><
                ><
                >foo<


                That is, one empty argument from "$1" (the argument to foo.sh), another from the hard-coded "" in the script, and then the fixed string foo.



                If either of $@ or $1 would have been unquoted, the empty values in question would disappear as part of word splitting.



                See:



                • This wiki page on word splitting: http://mywiki.wooledge.org/WordSplitting

                • Why does my shell script choke on whitespace or other special characters?

                • When is double-quoting necessary?






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Feb 2 at 12:18









                ilkkachuilkkachu

                59.8k895169




                59.8k895169



























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