Using sed with command-substitution text in the replacement part is not working












1














I have a CFN with cfn-init to deploy a Apache web server with specified virtual hosts. In the template, I use a AWS::CloudFormation::Init configset to replace local IPs with the Instance's private IP. 



  config:

    packages:...

    files:...

    services:...

    commands:

      replacePrivateIP:

        cwd: "/etc/httpd/conf"

        command: !Sub |

          sed -i 's@127.0.0.1@$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)@g' httpd.conf


The sed command works fine outside the CFN template. But in the CFN-init process, it simply replace "127.0.0.1" with the whole $(curl -s http://...) string.



How can I feed the instance private IP correctly into the httpd.conf file through cfn-init?






sed







share|improve this question





























    1














    I have a CFN with cfn-init to deploy a Apache web server with specified virtual hosts. In the template, I use a AWS::CloudFormation::Init configset to replace local IPs with the Instance's private IP. 



      config:
    
    packages:...
    
    files:...
    
    services:...
    
    commands:
    
      replacePrivateIP:
    
        cwd: "/etc/httpd/conf"
    
        command: !Sub |
    
          sed -i 's@127.0.0.1@$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)@g' httpd.conf


    The sed command works fine outside the CFN template. But in the CFN-init process, it simply replace "127.0.0.1" with the whole $(curl -s http://...) string.



    How can I feed the instance private IP correctly into the httpd.conf file through cfn-init?






    sed







    share|improve this question



























      1












      1








      1







      I have a CFN with cfn-init to deploy a Apache web server with specified virtual hosts. In the template, I use a AWS::CloudFormation::Init configset to replace local IPs with the Instance's private IP. 



        config:
      
    packages:...
      
    files:...
      
    services:...
      
    commands:
      
      replacePrivateIP:
      
        cwd: "/etc/httpd/conf"
      
        command: !Sub |
      
          sed -i 's@127.0.0.1@$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)@g' httpd.conf


      The sed command works fine outside the CFN template. But in the CFN-init process, it simply replace "127.0.0.1" with the whole $(curl -s http://...) string.



      How can I feed the instance private IP correctly into the httpd.conf file through cfn-init?






      sed







      share|improve this question















      I have a CFN with cfn-init to deploy a Apache web server with specified virtual hosts. In the template, I use a AWS::CloudFormation::Init configset to replace local IPs with the Instance's private IP. 



        config:
      
    packages:...
      
    files:...
      
    services:...
      
    commands:
      
      replacePrivateIP:
      
        cwd: "/etc/httpd/conf"
      
        command: !Sub |
      
          sed -i 's@127.0.0.1@$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)@g' httpd.conf


      The sed command works fine outside the CFN template. But in the CFN-init process, it simply replace "127.0.0.1" with the whole $(curl -s http://...) string.



      How can I feed the instance private IP correctly into the httpd.conf file through cfn-init?






      sed




      sed






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Dec 28 '18 at 12:19









      Inian

      38.9k63770




      38.9k63770










      asked Dec 28 '18 at 11:11









      Tomking ChenTomking Chen

      327




      327
























          1 Answer
          1






          active

          oldest

          votes


















          1














          The command-substitution syntax $(..) does not work when wrapped in single quotes which is as expected in bash or most other shells as they preserve the literal value present inside. For your substitution to happen, put it inside double-quotes as



          sed -i 's@127.0.0.1@'"$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)"'@g' httpd.conf


          Compare the outputs of echo '$(date)' and echo "$(date)" for a simple example of your case.






          share|improve this answer























            Your Answer






            StackExchange.ifUsing("editor", function () {
            StackExchange.using("externalEditor", function () {
            StackExchange.using("snippets", function () {
            StackExchange.snippets.init();
            });
            });
            }, "code-snippets");

            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "1"
            };
            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: true,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            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%2fstackoverflow.com%2fquestions%2f53957607%2fusing-sed-with-command-substitution-text-in-the-replacement-part-is-not-working%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









            1














            The command-substitution syntax $(..) does not work when wrapped in single quotes which is as expected in bash or most other shells as they preserve the literal value present inside. For your substitution to happen, put it inside double-quotes as



            sed -i 's@127.0.0.1@'"$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)"'@g' httpd.conf


            Compare the outputs of echo '$(date)' and echo "$(date)" for a simple example of your case.






            share|improve this answer




























              1














              The command-substitution syntax $(..) does not work when wrapped in single quotes which is as expected in bash or most other shells as they preserve the literal value present inside. For your substitution to happen, put it inside double-quotes as



              sed -i 's@127.0.0.1@'"$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)"'@g' httpd.conf


              Compare the outputs of echo '$(date)' and echo "$(date)" for a simple example of your case.






              share|improve this answer


























                1












                1








                1






                The command-substitution syntax $(..) does not work when wrapped in single quotes which is as expected in bash or most other shells as they preserve the literal value present inside. For your substitution to happen, put it inside double-quotes as



                sed -i 's@127.0.0.1@'"$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)"'@g' httpd.conf


                Compare the outputs of echo '$(date)' and echo "$(date)" for a simple example of your case.






                share|improve this answer














                The command-substitution syntax $(..) does not work when wrapped in single quotes which is as expected in bash or most other shells as they preserve the literal value present inside. For your substitution to happen, put it inside double-quotes as



                sed -i 's@127.0.0.1@'"$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)"'@g' httpd.conf


                Compare the outputs of echo '$(date)' and echo "$(date)" for a simple example of your case.







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Dec 28 '18 at 12:23

























                answered Dec 28 '18 at 12:18









                InianInian

                38.9k63770




                38.9k63770






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Stack Overflow!


                    • 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%2fstackoverflow.com%2fquestions%2f53957607%2fusing-sed-with-command-substitution-text-in-the-replacement-part-is-not-working%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







                    -

                    Popular posts from this blog

                    Monofisismo

                    Image
                    Monofisismo (do grego: monos - "único, singular" e physis - "natureza") é o ponto de vista cristológico que defende que, depois da união do divino e do humano na encarnação histórica, Jesus Cristo, como encarnação do Filho ou Verbo ( Logos ) de Deus, teria apenas uma única "natureza", a divina, e não uma síntese de ambas. O monofisismo é contraposto pelo diofisismo (ou "diafisismo"), que defende que Jesus preservou em si as duas naturezas. Historicamente, o monofisismo se refere primordialmente à posição dos que (especialmente no Egito e, em menor grau, na Síria) rejeitaram as decisões do Concílio de Calcedônia em 451 (o quarto concílio ecumênico). Os membros mais moderados entre eles, porém, defendem a teologia "miafisita", que se tornou a oficial para as Igrejas Ortodoxas Orientais. Muitos ortodoxos orientais, porém, rejeitam essa classificação, mesmo como um termo genérico, mas ele é amplamente utilizado na literatura históri...
                    Read more

                    Angular Downloading a file using contenturl with Basic Authentication

                    Image
                    0 I have a contentUrl when user clicks on that,file should be downloaded. If I try to browse the contentUrl in the browser it asks for Userid and password.I believe this is Basic Authentication.I dont want user to enter UserId and Password so I am passing it Authorization(Please see below code). Url looks some thing like this: http://XXX.XXX.XX.XXX:8080/flowable-rest/service/runtime/tasks/90875/attachments/90555/content let username : string = 'admin'; let pwd : string = 'test'; let headers = new Headers(); headers.set('Accept', 'text/json'); headers.append('Content-Type', 'application/json'); headers.set('Access-Control-Allow-Origin', '*'); headers.set('Access-Control-Allow-Methods','POST, GET, OPTIONS, PUT, DELETE'); head...
                    Read more

                    Olmecas

                    Image
                    Monumento 1, uma das quatro cabeças colossais encontradas em La Venta, com altura aproximada de 3 metros Olmecas é a designação do povo e da civilização que estiveram na origem da antiga cultura pré-colombiana da Mesoamérica e que se desenvolveram nas regiões tropicais do centro-sul do atual México durante o pré-clássico, próximo de onde hoje estão localizados os estados mexicanos de Veracruz e Tabasco, no Istmo de Tehuantepec, numa zona designada área nuclear olmeca. A cultura olmeca floresceu nesta região aproximadamente entre 1500 e 400 a.C., [ 1 ] e crê-se que tenha sido a civilização-mãe de todas as civilizações mesoamericanas que se desenvolveram posteriormente. [ 2 ] No entanto, desconhece-se a sua exacta filiação étnica, ainda que existam numerosas hipóteses colocadas para tentar resolver esta questão. O etnónimo olmeca foi cunhado pelos arqueólogos do século XX, e não devem confundir-se com os muito posteriores olmecas-xicalancas que ocuparam vários locais do México...
                    Read more