github.com/flavio/docker@v0.1.3-0.20170117145210-f63d1a6eec47/docs/reference/commandline/attach.md (about)

     1  ---
     2  title: "attach"
     3  description: "The attach command description and usage"
     4  keywords: "attach, running, container"
     5  ---
     6  
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    15  
    16  # attach
    17  
    18  ```markdown
    19  Usage: docker attach [OPTIONS] CONTAINER
    20  
    21  Attach to a running container
    22  
    23  Options:
    24        --detach-keys string   Override the key sequence for detaching a container
    25        --help                 Print usage
    26        --no-stdin             Do not attach STDIN
    27        --sig-proxy            Proxy all received signals to the process (default true)
    28  ```
    29  
    30  Use `docker attach` to attach to a running container using the container's ID
    31  or name, either to view its ongoing output or to control it interactively.
    32  You can attach to the same contained process multiple times simultaneously,
    33  screen sharing style, or quickly view the progress of your detached process.
    34  
    35  To stop a container, use `CTRL-c`. This key sequence sends `SIGKILL` to the
    36  container. If `--sig-proxy` is true (the default),`CTRL-c` sends a `SIGINT` to
    37  the container. You can detach from a container and leave it running using the
    38   `CTRL-p CTRL-q` key sequence.
    39  
    40  > **Note:**
    41  > A process running as PID 1 inside a container is treated specially by
    42  > Linux: it ignores any signal with the default action. So, the process
    43  > will not terminate on `SIGINT` or `SIGTERM` unless it is coded to do
    44  > so.
    45  
    46  It is forbidden to redirect the standard input of a `docker attach` command
    47  while attaching to a tty-enabled container (i.e.: launched with `-t`).
    48  
    49  While a client is connected to container's stdio using `docker attach`, Docker
    50  uses a ~1MB memory buffer to maximize the throughput of the application. If
    51  this buffer is filled, the speed of the API connection will start to have an
    52  effect on the process output writing speed. This is similar to other
    53  applications like SSH. Because of this, it is not recommended to run
    54  performance critical applications that generate a lot of output in the
    55  foreground over a slow client connection. Instead, users should use the
    56  `docker logs` command to get access to the logs.
    57  
    58  
    59  ## Override the detach sequence
    60  
    61  If you want, you can configure an override the Docker key sequence for detach.
    62  This is useful if the Docker default sequence conflicts with key sequence you
    63  use for other applications. There are two ways to define your own detach key
    64  sequence, as a per-container override or as a configuration property on  your
    65  entire configuration.
    66  
    67  To override the sequence for an individual container, use the
    68  `--detach-keys="<sequence>"` flag with the `docker attach` command. The format of
    69  the `<sequence>` is either a letter [a-Z], or the `ctrl-` combined with any of
    70  the following:
    71  
    72  * `a-z` (a single lowercase alpha character )
    73  * `@` (at sign)
    74  * `[` (left bracket)
    75  * `\\` (two backward slashes)
    76  *  `_` (underscore)
    77  * `^` (caret)
    78  
    79  These `a`, `ctrl-a`, `X`, or `ctrl-\\` values are all examples of valid key
    80  sequences. To configure a different configuration default key sequence for all
    81  containers, see [**Configuration file** section](cli.md#configuration-files).
    82  
    83  #### Examples
    84  
    85      $ docker run -d --name topdemo ubuntu /usr/bin/top -b
    86      $ docker attach topdemo
    87      top - 02:05:52 up  3:05,  0 users,  load average: 0.01, 0.02, 0.05
    88      Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
    89      Cpu(s):  0.1%us,  0.2%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
    90      Mem:    373572k total,   355560k used,    18012k free,    27872k buffers
    91      Swap:   786428k total,        0k used,   786428k free,   221740k cached
    92  
    93      PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
    94       1 root      20   0 17200 1116  912 R    0  0.3   0:00.03 top
    95  
    96       top - 02:05:55 up  3:05,  0 users,  load average: 0.01, 0.02, 0.05
    97       Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
    98       Cpu(s):  0.0%us,  0.2%sy,  0.0%ni, 99.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
    99       Mem:    373572k total,   355244k used,    18328k free,    27872k buffers
   100       Swap:   786428k total,        0k used,   786428k free,   221776k cached
   101  
   102         PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
   103             1 root      20   0 17208 1144  932 R    0  0.3   0:00.03 top
   104  
   105  
   106       top - 02:05:58 up  3:06,  0 users,  load average: 0.01, 0.02, 0.05
   107       Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
   108       Cpu(s):  0.2%us,  0.3%sy,  0.0%ni, 99.5%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
   109       Mem:    373572k total,   355780k used,    17792k free,    27880k buffers
   110       Swap:   786428k total,        0k used,   786428k free,   221776k cached
   111  
   112       PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
   113            1 root      20   0 17208 1144  932 R    0  0.3   0:00.03 top
   114      ^C$
   115      $ echo $?
   116      0
   117      $ docker ps -a | grep topdemo
   118      7998ac8581f9        ubuntu:14.04        "/usr/bin/top -b"   38 seconds ago      Exited (0) 21 seconds ago                          topdemo
   119  
   120  And in this second example, you can see the exit code returned by the `bash`
   121  process is returned by the `docker attach` command to its caller too:
   122  
   123      $ docker run --name test -d -it debian
   124      275c44472aebd77c926d4527885bb09f2f6db21d878c75f0a1c212c03d3bcfab
   125      $ docker attach test
   126      root@f38c87f2a42d:/# exit 13
   127      exit
   128      $ echo $?
   129      13
   130      $ docker ps -a | grep test
   131      275c44472aeb        debian:7            "/bin/bash"         26 seconds ago      Exited (13) 17 seconds ago                         test