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Nicholas Saunders
Asked: 2020-08-05 00:30:00 +0800 CST

How can AWK be used to list Docker containers?

  • 772

I'm looking to use tools along the lines of:

  • grep
  • sed
  • AWK

to work with Docker.

Listing containers:

docker container ls | awk '{print $1}'

Results:

CONTAINER
490e3d669259
a44230a617e1

How can I omit the "header"?

Here's the full output for docker container ls should that prove useful:

CONTAINER ID  IMAGE  COMMAND                 CREATED        STATUS        PORTS                                        NAMES
490e3d669259  jetty  "/docker-entrypoint.…"  3 minutes ago  Up 3 minutes  0.0.0.0:80->8080/tcp, 0.0.0.0:443->8443/tcp  quirky_antonelli
a44230a617e1  jetty  "/docker-entrypoint.…"  4 minutes ago  Up 4 minutes  8080/tcp                                     goofy_hamilton

I am just looking for the values under the container heading.

command-line docker text-processing

3 Answers

  1. Best Answer

    With awk, you can skip the first line (or record) using NR > 1:

    docker container ls | awk 'NR > 1 {print $1}'

    But you don't need that. You can just tell docker to format the output:

    % docker container ls --format '{{.ID}}'
bd1299b0dd5a
8fcbcd67a843
    • 30

  2. The command you're looking for is tail -n +2:

    docker container ls | awk '{print $1}' | tail -n +2

    Explanation here (there is also an option using sed - guess you have to try which is fastest).

    • 3

  3. Docker gives you more control so that you don't actually need to use a second command piped to do post-processing. In this instance you can just use the --quiet|-q option.

    $ docker container ls -q
490e3d669259
a44230a617e1

    Many command line tools use similar conventions like --help that give more detailed information about usage options. Here is the output of docker container ls --help:

    # docker container ls --help

Usage:  docker container ls [OPTIONS]

List containers

Aliases:
  ls, ps, list

Options:
  -a, --all             Show all containers (default shows just running)
  -f, --filter filter   Filter output based on conditions provided
      --format string   Pretty-print containers using a Go template
  -n, --last int        Show n last created containers (includes all states) (default -1)
  -l, --latest          Show the latest created container (includes all states)
      --no-trunc        Don't truncate output
  -q, --quiet           Only display numeric IDs
  -s, --size            Display total file sizes
    • 1