I am new to Linux stuff and would like to know how to run command while opening the shell through /bin/bash?
Eg the steps that I want to perform:
Step1: Run the docker exec command to start the quickstart virtual machine.
$ docker exec -it 7f8c1a16e5b2 /bin/bash
Step2: The above command gives the handle of the quickstart vm on the console. Now I want to run the below command by default when ever some one starts the docker quickstart console (step 1)
cd
. ./.bash_profile
I need some guidance on how to do this. Obviously, putting all these statements in one shell script isn't helping as the commands of Step2 are to be executed in the newly opened shell (of quickstart vm). The idea is to put all these statements in a single shell script and execute it when we want to get hold of the session within the VM console.
You can pass the commands you want to be executed inside the container to bash with the -c option.
That would look something like this:
docker exec -it 7f8c1a16e5b2 /bin/bash -c "cd && . ./.bash_profile && /bin/bash"
Related
To simplify test execution for several different container I want to create an alias to use the same command for every container.
For example for a backend container I want to be able to use docker exec -t backend test instead of docker exec -t backend pytest test
So I add this line in my backend Dockerfile :
RUN echo alias test="pytest /app/test" >> ~/.bashrc
But when I do docker exec -t backend test it doesn't work, otherwise it works when I do docker exec -ti backend bash then test.
I saw that it is because alias in .bashrc works only if we use interactive terminal.
How can I get around that?
docker exec does not run the shell, so .bashrc is just never used.
Create an executable in PATH, most probably in /usr/local/bin. Note that test is a very basic shell command, use a different unique name.
That alias will only work for interactive shells, if you want that alias to work on other programs:
RUN echo -e '#!/bin/bash\npytest /app/test' > /usr/bin/mypytest && \
chmod +x /usr/bin/mypytest
If we've to do some operations(execute commands) inside of docker container, we can go inside it and then execute commands -
docker exec -it <ContainerId> bash # go inside of container
cd /usr/local/tomcat/bin # hit command inside of container
./catalina.sh start # hit command inside of container
After this we need to hit Ctrl + C to come out of container.
But without going inside of container, can we execute commands inside of it from host directly like -
// command to attach to container
// command 1 to execute
// command 2 to execute
// no command required to come out of container as above commands directly hit from hosts
yes you can run your command at once:
docker exec -it <ContainerId> /usr/local/tomcat/bin/catalina.sh start
if you need to run multiple commands, you can pass them straight to bash:
docker exec -it <ContainerId> bash -c 'command1 && command2'
I am new to the linux world and trying to learn Docker.
I have two examples:
#example 1
$ docker run -ti ubuntu:latest bash
#example 2
$ docker run -ti ubuntu:latest
In example 1 it would allow me access to the terminal and example 2 is the same outcome. I understand that adding bash creates a bash session, and if that means being able run bash scripts, I am able to do echo on both examples, so I do not really see the difference.
What exactly does adding bash to docker run do? Given this context, what is the difference of having and not having a bash argument?
Specifying an explicit command overrides the default command given in the Dockerfile.
If the default CMD in the Dockerfile is already bash, then specifying bash on the command line has no effect.
If you look at the ubuntu Dockerfile on github, you can see that that is the case here:
CMD ["bash"]
Thus, you're just explicitly asserting the command that is already run by default anyhow.
I am running Docker (1.10.2) on Windows. I created a script to echo 'Hello World' on my machine and stored it in C:/Users/username/MountTest. I created a new container and mounted this directory (MountTest) as a data volume. The command I ran to do so is shown below:
docker run -t -i --name mounttest -v /c/Users/sarin/MountTest:/home ubuntu /bin/bash
Next, I run the command to execute the script within the container mounttest.
docker exec -it mounttest sh /home/helloworld.sh
The result is as follows:
: not foundworld.sh: 2: /home/helloworld.sh:
Hello World
I get the desired output (echo Hello World) but I want to understand the reason behind the not found errors.
Note: This question might look similar to Run shell script on docker from shared volume, but it addresses permission related issues.
References:
The helloworld.sh file:
#!/bin/sh
echo 'Hello World'
The mounted volumes information is captured below.
Considering the default ENTRYPOINT for the 'ubuntu' image is sh -c, the final command executed on docker exec is:
sh -c 'sh /home/helloworld.sh'
It looks a bit strange and might be the cause of the error message.
Try simply:
docker exec -it mounttest /home/helloworld.sh
# or
docker exec -it mounttest sh -c '/home/helloworld.sh'
Of course, the docker exec should be done in a boot2docker ssh session, simalar to the shell session in which you did a docker run.
Since the docker run opens a bash, you should make a new boot2docker session (docker-machine ssh), and in that new boot2docker shell session, try the docker exec.
Trying docker exec from within the bash made by docker run means trying to do DiD (Docker in Docker). It is not relevant for your test.
I want to create a bash script that removes a user from a mongodb database that is running inside a docker container.
Normally through the terminal I would execute docker exec -it mycontainername bash
and then once I'm in the container I execute mongo mydbname --eval "db.users.remove({"firstname":"Bob"})"
I just have no idea how to do it in a linux bash script.
After I execute script that contains the docker exec command, it leaves the script and opens the docker container's terminal and prompts me to enter a command.
Would using the detached -d flag work?
Found out you can replace bash with the name of the shell you want to open, so in this case mongo.