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
          1






          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























            Your Answer








            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "106"
            };
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function() {
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled) {
            StackExchange.using("snippets", function() {
            createEditor();
            });
            }
            else {
            createEditor();
            }
            });

            function createEditor() {
            StackExchange.prepareEditor({
            heartbeatType: 'answer',
            autoActivateHeartbeat: false,
            convertImagesToLinks: false,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: null,
            bindNavPrevention: true,
            postfix: "",
            imageUploader: {
            brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
            contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
            allowUrls: true
            },
            onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            });


            }
            });














            draft saved

            draft discarded


















            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f482431%2fbash-use-raw-binary-in-variable-as-executable%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            1 Answer
            1






            active

            oldest

            votes








            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

                1




                1






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Unix & Linux Stack Exchange!


                    • Please be sure to answer the question. Provide details and share your research!

                    But avoid …



                    • Asking for help, clarification, or responding to other answers.

                    • Making statements based on opinion; back them up with references or personal experience.


                    To learn more, see our tips on writing great answers.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f482431%2fbash-use-raw-binary-in-variable-as-executable%23new-answer', 'question_page');
                    }
                    );

                    Post as a guest















                    Required, but never shown





















































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown

































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown







                    -

                    這個網誌中的熱門文章

                    Tangent Lines Diagram Along Smooth Curve

                    圖片
                    7 1 I am trying to replicate a diagram and have a minimal example. I don't know how to add additional tangents between the specified points and preserve smoothness. documentclass{article} usepackage{tikz} usetikzlibrary{calc,intersections} begin{document} begin{tikzpicture} % Axes draw [->, name path=x] (-1,0) -- (11,0) node [right] {$x$}; draw [->] (0,-1) -- (0,6) node [above] {$y$}; % Origin node at (0,0) [below left] {$0$}; % Points coordinate (start) at (1,-0.8); coordinate (c1) at (3,3); coordinate (c2) at (5.5,1.5); coordinate (c3) at (8,4); coordinate (end) at (10.5,-0.8); % show the points foreach n in {start,c1,c2,c3,end} fill [black] (n) circle (2pt) node [below] {}; % join the coordinates draw [thick,name path=curve] (start) to[out=70,in=180] (c1) to[out=0,in=180]
                    閱讀完整內容

                    Yusuf al-Mu'taman ibn Hud

                    圖片
                    Main article: Taifa of Zaragoza Al-Mu'taman Ruler of Zaragoza Reign 1081–1085 Predecessor Ahmad al-Muqtadir Successor Al-Mustain II Born Zaragoza Died 1085 Full name Yusuf ibn Ahmad al-Mu'taman ibn Hūd House Banu Hud Yusuf ibn Ahmad al-Mu'taman ibn Hūd (Arabic: المؤتمن بالله يوسف إبن أحمد إبن هود ‎, al-Mutaman bi l-Lah , died c. 1085) was the third king of the Banu Hud dynasty who ruled over the Taifa of Zaragoza from 1081 to 1085. Yusuf al-Mutaman reigned during the height of power of Muslim Zaragoza , following the thriving period of his father Ahmad al-Muqtadir. He continued his father's efforts and created around him a court of intellectuals, living in the beautiful palace of Aljafería, nicknamed as "the palace of joy". Al-Mu'taman was also a scholarly king and a patron of science, philosophy and arts. As an example of a wise king, he knew astrology, philosophy, and especially mathematics, a discipline in which
                    閱讀完整內容

                    Zucchini

                    圖片
                    This article is about the vegetable. For other uses, see Zucchini (disambiguation). Zucchini (courgette) A striped and a uniform color zucchini Genus Cucurbita Species Cucurbita pepo Origin 19th century northern Italy The zucchini ( / z uː ˈ k iː n i / , American English) or courgette ( / k ʊər ˈ ʒ ɛ t / , British English) is a summer squash which can reach nearly 1 metre (100 cm; 39 in) in length, but is usually harvested when still immature at about 15 to 25 cm (6 to 10 in). [1] A zucchini is a thin-skinned cultivar of what in Britain and Ireland is referred to as a marrow. [2] [3] In South Africa, a zucchini is known as a baby marrow. Along with certain other squashes and pumpkins, the zucchini belongs to the species Cucurbita pepo . It can be dark or light green. A related hybrid, the golden zucchini, is a deep yellow or orange color. [4] In a culinary context, the zucchini is treated as a vegetable; it is usually cooked and presented as a savory dish o
                    閱讀完整內容