I want to write a shell script that enters into a running docker container, edits a specific file and then exits it.
My initial attempt was this -
Create run.sh file.
Paste the following commands into it
docker exec -it container1 bash
sed -i -e 's/false/true/g' /opt/data_dir/gs.xml
exit
Run the script -
bash ./run.sh
However, once the script enters into the container1 it lands to the bash terminal of it. Seems like the whole script breaks as soon as I enter into the container, leaving parent container behind which contains the script.
The issue is solved By using the below piece of code
myHostName="$(hostname)"
docker exec -i -e VAR=${myHostName} root_reverse-proxy_1 bash <<'EOF'
sed -i -e "s/ServerName .*/ServerName $VAR/" /etc/httpd/conf.d/vhosts.conf
echo -e "\n Updated /etc/httpd/conf.d/vhosts.conf $VAR \n"
exit
I think you are close. You can try something like:
docker exec container1 sed -i -e 's/false/true/g' /opt/data_dir/gs.xml
Explanations:
-it is for interactive session, so you don't need it here.
docker can execute any command (like sed). You don't have to run sed via bash
Related
The following script.sh is executed:
#!/bin/bash
set -eu
# code ...
su buser
mkdir /does/not/work
echo $?
echo This should not be printed
Output:
1
This should not be printed
How i execute the script:
docker exec -i fancy_container bash < script.sh
Question: Why does the script not terminate after the failing command even when set -e was defined and how can i get the script to exit on any failing command? I think the key point is the '<' operator, which i do not understand exactly how it executes the script.
Notes:
-e means: Abort script at first error, when a command exits with non-zero status (except in until or while loops, if-tests, list constructs)
Possible solution:
docker exec -i fancy_container bash -c "cat > tmp.sh; bash tmp.sh" < script.sh
How it works:
< script.sh - Pipe all rows of this file from the host, to the docker exec command.
cat > tmp.sh - Save the incoming piped content to a file inside the container.
bash tmp.sh - Execute the file as-whole inside the container, which means -e works again as expected!
But i still don't know why the initial approach isn't working.
I want to run these two command in a loop:
for i in cat input:
do
winpty Kubectl exec -it $i -n image -c podname -- sh
2nd command
done
When I am running the .sh file, the first command works fine and after than nothing is happening.Can anybody help on this?I am running through gitbash from windows machine
I'm a bash rookie, but maybe it's because of the lack of a defined -d directory for unzipped files?
For our application running inside a container it is preferable that it receives a SIGTERM when the container is being (gracefully) shutdown. At the same time, we want it's output to go to a log file.
In the startscript of our docker container, we had therefore been using bash's exec similar to this
exec command someParam >> stdout.log
That worked just fine, command replaced the shell that had been the container's root process and would receive the SIGTERM.
Since the application tends to log a lot, we decided to add log rotation by using Apache's rotatelogs tool, i.e.
exec command | rotatelogs -n 10 stdout.log 10M
Alas, it seems that by using the pipe, exec can no longer have command replace the shell. When looking at the processes in the running container with pstree -p, it now looks like this
mycontainer#/#pstree -p
start.sh(1)-+-command(118)
`-rotatelogs(119)
So bash remains the root process, and does not pass the SIGTERM on to command.
Before stumbling upon exec, I had found an approach that installs a signal handler into the bash script, which would then itself send a SIGTERM to the command process using kill. However, this became really convoluted, getting the PID was also not always straightforward, and I would like to preserve the convenience of exec when it comes to signal handling and get piping for log rotation.
Any idea how to accomplish this?
Perhaps you want
exec sh -c 'command | rotatelogs -n 10 stdout.log 10M'
I was able to get around this by using process substitution. For your specific case the following may work.
exec command > >(rotatelogs -n 10 stdout.log 10M)
To reproduce the scenario I built this simple Dockerfile
FROM perl
SHELL ["/bin/bash", "-c"]
# The following will gracefully terminate upon docker stop
CMD exec perl -e '$SIG{TERM} = sub { $|++; print "Caught a sigterm!\n"; sleep(5); die "is the end!" }; sleep(30);' 2>&1 > >(tee /my_log)
# The following won't gracefully terminate upon docker stop
#CMD exec perl -e '$SIG{TERM} = sub { $|++; print "Caught a sigterm!\n"; sleep(5); die "is the end!" }; sleep(30);' 2>&1 | tee /my_log
Build docker build -f Dockerfile.meu -t test .
Run docker run --name test --rm -ti test
Stop it docker stop test
Output:
Caught a sigterm!
is the end! at -e line 1.
I want to execute a command like docker exec "$(docker-compose ps -q web)" start.sh from golang script using exec.command(). The problem is getting the command inside $() to execute.
The command inside of $() is executed and replaced with its output by your shell on the command line (typically bash but can be sh or others). exec.Command is running the program directly, so that replacement isn't happening. This means you need to pass that command into bash so it will interpret and execute the command:
bash -c "docker exec \"$(docker-compose ps -q web)\" start.sh"
Code Example:
exec.Command("/bin/sh", "-c", "docker exec \"$(docker-compose ps -q web)\" start.sh")
Alternatively, you can run docker-compose ps -q web yourself, get its output and do the substitution instead of having bash do it for you.
I have a current bash script. echo will display all results when cmd has been finished. But I want in real time see output coming line by line when script is in execution process. How can I achieve that?
#!/bin/bash
echo $(docker build -t goapp -f deployments/dev/Dockerfile .)
docker already prints its output to standard output; that's why you can capture it with $(...) and pass it as arguments to echo. Just run docker:
#!/bin/bash
docker build -t goal -f deployments/dev/Dockerfile .