mirror of https://github.com/docker/docs.git
128 lines
3.0 KiB
Markdown
128 lines
3.0 KiB
Markdown
---
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description: CLI and log output formatting reference
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keywords: format, formatting, output, templates, log
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title: Format command and log output
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weight: 40
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aliases:
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- /engine/admin/formatting/
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- /config/formatting/
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---
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Docker supports [Go templates](https://golang.org/pkg/text/template/) which you
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can use to manipulate the output format of certain commands and log drivers.
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Docker provides a set of basic functions to manipulate template elements.
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All of these examples use the `docker inspect` command, but many other CLI
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commands have a `--format` flag, and many of the CLI command references
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include examples of customizing the output format.
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> [!NOTE]
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>
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> When using the `--format` flag, you need observe your shell environment.
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> In a POSIX shell, you can run the following with a single quote:
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>
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> ```console
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> $ docker inspect --format '{{join .Args " , "}}'
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> ```
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>
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> Otherwise, in a Windows shell (for example, PowerShell), you need to use single quotes, but
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> escape the double quotes inside the parameters as follows:
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>
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> ```console
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> $ docker inspect --format '{{join .Args \" , \"}}'
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> ```
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>
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## join
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`join` concatenates a list of strings to create a single string.
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It puts a separator between each element in the list.
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```console
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$ docker inspect --format '{{join .Args " , "}}' container
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```
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## table
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`table` specifies which fields you want to see its output.
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```console
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$ docker image list --format "table {{.ID}}\t{{.Repository}}\t{{.Tag}}\t{{.Size}}"
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```
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## json
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`json` encodes an element as a json string.
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```console
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$ docker inspect --format '{{json .Mounts}}' container
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```
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## lower
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`lower` transforms a string into its lowercase representation.
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```console
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$ docker inspect --format "{{lower .Name}}" container
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```
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## split
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`split` slices a string into a list of strings separated by a separator.
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```console
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$ docker inspect --format '{{split .Image ":"}}' container
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```
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## title
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`title` capitalizes the first character of a string.
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```console
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$ docker inspect --format "{{title .Name}}" container
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```
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## upper
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`upper` transforms a string into its uppercase representation.
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```console
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$ docker inspect --format "{{upper .Name}}" container
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```
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## pad
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`pad` adds whitespace padding to a string. You can specify the number of spaces to add before and after the string.
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```console
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$ docker image list --format '{{pad .Repository 5 10}}'
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```
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This example adds 5 spaces before the image repository name and 10 spaces after.
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## truncate
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`truncate` shortens a string to a specified length. If the string is shorter than the specified length, it remains unchanged.
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```console
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$ docker image list --format '{{truncate .Repository 15}}'
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```
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This example displays the image repository name, truncating it to the first 15 characters if it's longer.
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## println
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`println` prints each value on a new line.
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```console
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$ docker inspect --format='{{range .NetworkSettings.Networks}}{{println .IPAddress}}{{end}}' container
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```
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## Hint
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To find out what data can be printed, show all content as json:
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```console
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$ docker container ls --format='{{json .}}'
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```
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