{"id":48360,"date":"2025-02-08T08:12:19","date_gmt":"2025-02-08T08:12:19","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=48360"},"modified":"2025-07-12T05:38:46","modified_gmt":"2025-07-12T05:38:46","slug":"docker-exec","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/docker-exec\/","title":{"rendered":"Docker commands Guide – docker exec with examples"},"content":{"rendered":"\n

Here\u2019s a complete tutorial<\/strong> on the docker exec<\/code> command, including its purpose<\/strong>, how to use it<\/strong>, and a comprehensive list of examples<\/strong>.<\/p>\n\n\n\n

\n\n\n\n

What is docker exec<\/code>?<\/strong><\/h2>\n\n\n\n

docker exec<\/code> is used to run a command inside a running Docker container<\/strong>. Unlike docker attach<\/code>, which connects to the container\u2019s primary process, docker exec<\/code> allows you to execute new commands in real-time within the container without affecting the main process.<\/p>\n\n\n\n

Key Features of docker exec<\/code>:<\/strong><\/p>\n\n\n\n

    \n
  • Run interactive commands<\/strong> (like a bash shell) in a running container.<\/li>\n\n\n\n
  • Useful for debugging<\/strong>, maintenance<\/strong>, and inspection<\/strong>.<\/li>\n\n\n\n
  • Supports running single commands<\/strong> or opening an interactive shell<\/strong>.<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n

    Basic Syntax<\/strong><\/h2>\n\n\n
    docker<\/span> exec<\/span> [OPTIONS]<\/span> CONTAINER<\/span> COMMAND<\/span> [ARG...]<\/span>\n<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
    Common Options:<\/strong><\/h3>\n\n\n\n
      \n
    • -i<\/code> \u2192 Keep STDIN open<\/strong> (interactive mode).<\/li>\n\n\n\n
    • -t<\/code> \u2192 Allocate a pseudo-TTY<\/strong> (useful for interactive commands like bash<\/code>).<\/li>\n\n\n\n
    • -e<\/code> \u2192 Set environment variables inside the container.<\/li>\n\n\n\n
    • --privileged<\/code> \u2192 Run the command with elevated privileges inside the container.<\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n
      Examples of docker exec<\/code><\/strong><\/h2>\n\n\n\n
      1. Run a Simple Command in a Container<\/strong><\/h3>\n\n\n
      docker exec my_container ls \/var<\/span>\/log\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      This command lists the contents of \/var\/log<\/code> in my_container<\/code>.<\/p>\n\n\n\n
      \n\n\n\n
      2. Open an Interactive Shell (bash<\/code>)<\/strong><\/h3>\n\n\n
      docker exec -it my_container bash\n<\/code><\/span><\/pre>\n\n\n
      This opens an interactive bash shell inside my_container<\/code>.<\/p>\n\n\n\n
      If the container doesn\u2019t have bash<\/code> installed, use sh<\/code>:<\/p>\n\n\n
      docker exec -it my_container sh\n<\/code><\/span><\/pre>\n\n\n
      \n\n\n\n
      3. Run a Command with Elevated Privileges<\/strong><\/h3>\n\n\n
      docker exec --privileged -it my_container bash\n<\/code><\/span><\/pre>\n\n\n
      This runs the bash shell with elevated privileges, allowing access to restricted parts of the filesystem.<\/p>\n\n\n\n
      \n\n\n\n
      4. Execute a Command with Environment Variables<\/strong><\/h3>\n\n\n
      docker exec -e ENV_VAR=value my_container printenv ENV_VAR\n<\/code><\/span><\/pre>\n\n\n
      This sets ENV_VAR<\/code> inside the container and prints its value.<\/p>\n\n\n\n
      \n\n\n\n
      5. Run a Command in a Detached Mode<\/strong><\/h3>\n\n\n\n
      You can run a command without waiting for it to finish:<\/p>\n\n\n
      docker exec -d my_container touch \/tmp\/newfile.txt\n<\/code><\/span><\/pre>\n\n\n
      This creates a file \/tmp\/newfile.txt<\/code> inside the container and immediately detaches.<\/p>\n\n\n\n
      \n\n\n\n
      6. Inspect Running Processes<\/strong><\/h3>\n\n\n
      docker exec my_container ps aux\n<\/code><\/span><\/pre>\n\n\n
      This lists all running processes in the container.<\/p>\n\n\n\n
      \n\n\n\n
      7. Monitor Resource Usage<\/strong><\/h3>\n\n\n
      docker exec my_container top\n<\/code><\/span><\/pre>\n\n\n
      This displays resource usage (CPU, memory) inside the container.<\/p>\n\n\n\n
      \n\n\n\n
      8. Check the Container\u2019s Hostname<\/strong><\/h3>\n\n\n
      docker exec my_container hostname\n<\/code><\/span><\/pre>\n\n\n
      Returns the hostname of the container.<\/p>\n\n\n\n
      \n\n\n\n
      9. Inspect Networking Information<\/strong><\/h3>\n\n\n
      docker exec my_container ifconfig\n<\/code><\/span><\/pre>\n\n\n
      Displays the network configuration of the container.<\/p>\n\n\n\n
      If ifconfig<\/code> isn\u2019t available, use ip<\/code>:<\/p>\n\n\n
      docker exec my_container ip a\n<\/code><\/span><\/pre>\n\n\n
      \n\n\n\n
      10. Check Disk Space<\/strong><\/h3>\n\n\n
      docker exec my_container df -h\n<\/code><\/span><\/pre>\n\n\n
      Shows the container’s disk usage.<\/p>\n\n\n\n
      \n\n\n\n
      11. Debug an Application Log<\/strong><\/h3>\n\n\n
      docker exec my_container tail -f \/var<\/span>\/log\/app.log\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
      This command follows the application log inside the container.<\/p>\n\n\n\n
      \n\n\n\n
      12. Interact with a Database in a Container<\/strong><\/h3>\n\n\n\n
      MySQL Example<\/strong>:<\/h4>\n\n\n
      docker exec -it my_mysql mysql -u root -p\n<\/code><\/span><\/pre>\n\n\n
      This opens a MySQL client inside the my_mysql<\/code> container.<\/p>\n\n\n\n
      PostgreSQL Example<\/strong>:<\/h4>\n\n\n
      docker exec -it my_postgres psql -U postgres\n<\/code><\/span><\/pre>\n\n\n
      \n\n\n\n
      13. Restart a Service Inside the Container<\/strong><\/h3>\n\n\n
      docker exec my_container service nginx restart\n<\/code><\/span><\/pre>\n\n\n
      Restarts the NGINX service inside the container.<\/p>\n\n\n\n
      \n\n\n\n
      14. Copy a File from One Directory to Another<\/strong><\/h3>\n\n\n
      docker exec my_container cp \/path\/to\/source \/path\/to\/destination\n<\/code><\/span><\/pre>\n\n\n
      \n\n\n\n
      15. Run a Health Check<\/strong><\/h3>\n\n\n\n
      If the container has a custom health check script:<\/p>\n\n\n
      docker exec my_container \/usr\/local\/bin\/health_check.sh\n<\/code><\/span><\/pre>\n\n\n
      \n\n\n\n
      Combining docker exec<\/code> with Other Commands<\/strong><\/h2>\n\n\n\n
        \n
      1. docker exec<\/code> + docker logs<\/code>:<\/strong>
        Debug a service by checking its logs and running commands in the container. docker logs my_container docker exec -it my_container bash<\/code><\/li>\n\n\n\n
      2. docker exec<\/code> + docker cp<\/code>:<\/strong>
        Copy a file into the container and then run it. docker cp .\/script.sh my_container:\/tmp\/script.sh docker exec my_container sh \/tmp\/script.sh<\/code><\/li>\n<\/ol>\n\n\n\n
        \n\n\n\n
        List of Common docker exec<\/code> Commands<\/strong><\/h2>\n\n\n\n
        Command<\/strong><\/th>Description<\/strong><\/th><\/tr><\/thead>
        docker exec my_container ls \/var\/log<\/code><\/td>List files in \/var\/log<\/code><\/td><\/tr>
        docker exec -it my_container bash<\/code><\/td>Open an interactive bash shell<\/td><\/tr>
        docker exec -it my_container sh<\/code><\/td>Open an interactive shell<\/td><\/tr>
        docker exec my_container ps aux<\/code><\/td>List running processes<\/td><\/tr>
        docker exec -e VAR=value my_container env<\/code><\/td>Set and print an environment variable<\/td><\/tr>
        docker exec --privileged my_container bash<\/code><\/td>Run bash with elevated privileges<\/td><\/tr>
        docker exec -d my_container touch \/tmp\/file<\/code><\/td>Run a command in detached mode<\/td><\/tr>
        docker exec my_container tail -f \/var\/log\/app.log<\/code><\/td>Follow the log file inside the container<\/td><\/tr>
        docker exec my_mysql mysql -u root -p<\/code><\/td>Open MySQL client inside a MySQL container<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
        \n\n\n\n
        Best Practices for Using docker exec<\/code>:<\/strong><\/h2>\n\n\n\n
          \n
        1. Use docker exec<\/code> for debugging<\/strong> and interactive tasks.<\/li>\n\n\n\n
        2. Combine with docker logs<\/code><\/strong> to troubleshoot container issues.<\/li>\n\n\n\n
        3. Avoid running critical commands<\/strong> unless you know the container\u2019s behavior.<\/li>\n\n\n\n
        4. Use -it<\/code> for interactive tasks<\/strong> (like opening a shell).<\/li>\n<\/ol>\n\n\n\n
          \n\n\n\n
          Common Errors and Solutions<\/strong><\/h2>\n\n\n\n
            \n
          1. “OCI runtime exec failed: exec failed: container not running”<\/strong>
            \u2192 Ensure the container is running by checking with docker ps<\/code>. Start it with docker start CONTAINER_NAME<\/code>.<\/li>\n\n\n\n
          2. “command not found”<\/strong>
            \u2192 The specified command may not be installed in the container. Use sh<\/code> or bash<\/code> to explore and confirm.<\/li>\n\n\n\n
          3. “permission denied”<\/strong>
            \u2192 Use --privileged<\/code> or check file permissions inside the container.<\/li>\n<\/ol>\n\n\n\n
            \n\n\n\n
            <\/p>\n","protected":false},"excerpt":{"rendered":"
            Here\u2019s a complete tutorial on the docker exec command, including its purpose, how to use it, and a comprehensive list of examples. What is docker exec? docker exec is used to run a command inside a running Docker container. Unlike docker attach, which connects to the container\u2019s primary process, docker exec allows you to execute…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_joinchat":[],"footnotes":""},"categories":[4862],"tags":[],"class_list":["post-48360","post","type-post","status-publish","format-standard","hentry","category-docker"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48360","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=48360"}],"version-history":[{"count":2,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48360\/revisions"}],"predecessor-version":[{"id":48362,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/48360\/revisions\/48362"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=48360"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=48360"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=48360"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}