Format command and log output

Docker supports Go templates which you can use to manipulate the output format of certain commands and log drivers.

Docker provides a set of basic functions to manipulate template elements. All of these examples use the docker inspect command, but many other CLI commands have a --format flag, and many of the CLI command references include examples of customizing the output format.


When using the --format flag, you need observe your shell environment. In a POSIX shell, you can run the following with a single quote:

$ docker inspect --format '{{join .Args " , "}}'

Otherwise, in a Windows shell (for example, PowerShell), you need to use single quotes, but escape the double quotes inside the parameters as follows:

$ docker inspect --format '{{join .Args \" , \"}}'


join concatenates a list of strings to create a single string. It puts a separator between each element in the list.

$ docker inspect --format '{{join .Args " , "}}' container


table specifies which fields you want to see its output.

$ docker image list --format "table {{.ID}}\t{{.Repository}}\t{{.Tag}}\t{{.Size}}"


json encodes an element as a json string.

$ docker inspect --format '{{json .Mounts}}' container


lower transforms a string into its lowercase representation.

$ docker inspect --format "{{lower .Name}}" container


split slices a string into a list of strings separated by a separator.

$ docker inspect --format '{{split .Image ":"}}' container


title capitalizes the first character of a string.

$ docker inspect --format "{{title .Name}}" container


upper transforms a string into its uppercase representation.

$ docker inspect --format "{{upper .Name}}" container


println prints each value on a new line.

$ docker inspect --format='{{range .NetworkSettings.Networks}}{{println .IPAddress}}{{end}}' container


To find out what data can be printed, show all content as json:

$ docker container ls --format='{{json .}}'