Bash: Use raw binary in variable as executable?












2















I'd like to create a variable containing binary data, then execute in a command. Example:



#!/bin/bash

var="$(cat /bin/sleep)"

"$var" 9999





linux bash shell ubuntu variable







share|improve this question



























    2















    I'd like to create a variable containing binary data, then execute in a command. Example:



    #!/bin/bash
    
var="$(cat /bin/sleep)"
    
"$var" 9999





    linux bash shell ubuntu variable







    share|improve this question

























      2












      2








      2


      0






      I'd like to create a variable containing binary data, then execute in a command. Example:



      #!/bin/bash
      
var="$(cat /bin/sleep)"
      
"$var" 9999





      linux bash shell ubuntu variable







      share|improve this question














      I'd like to create a variable containing binary data, then execute in a command. Example:



      #!/bin/bash
      
var="$(cat /bin/sleep)"
      
"$var" 9999





      linux bash shell ubuntu variable




      linux bash shell ubuntu variable






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 17 '18 at 23:59









      user321517user321517

      202




      202






















          1 Answer
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          You cannot execute a variable like that because:




          • the kernel executes files,

          • the shell can execute command lines stored in variables, but it cannot interpret binary data

          • storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)

          • even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable


          So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.






          share|improve this answer























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            oldest

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            4














            You cannot execute a variable like that because:




            • the kernel executes files,

            • the shell can execute command lines stored in variables, but it cannot interpret binary data

            • storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)

            • even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable


            So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.






            share|improve this answer




























              4














              You cannot execute a variable like that because:




              • the kernel executes files,

              • the shell can execute command lines stored in variables, but it cannot interpret binary data

              • storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)

              • even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable


              So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.






              share|improve this answer


























                4












                4








                4







                You cannot execute a variable like that because:




                • the kernel executes files,

                • the shell can execute command lines stored in variables, but it cannot interpret binary data

                • storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)

                • even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable


                So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.






                share|improve this answer













                You cannot execute a variable like that because:




                • the kernel executes files,

                • the shell can execute command lines stored in variables, but it cannot interpret binary data

                • storing a binary file's contents in a variable will likely not work well, because null bytes may be present in the file (and you can't have null bytes in variables of most shells)

                • even if you used process substitution to get a temporary file with the contents of that variable, process substitution file handles won't be executable


                So you'll have to store the contents in a file, make that file executable, hope that nothing got missed because of a null bytes, and execute that file.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 18 '18 at 0:52









                murumuru

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