Format command and log output

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Docker uses Go templates which allow users to manipulate the output format of certain commands and log drivers. Each command a driver provides has a detailed list of elements they support in their templates:

Template functions

Docker provides a set of basic functions to manipulate template elements. This is the complete list of the available functions with examples:


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


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 (join .Names "/") "/"}}' 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
format, formatting, output, templates, log