jenkins pod cannot find its own local programs - jenkins

Question

I have Jenkins using kubernetes for creating ephemeral pods.
Recently I wanted to build .net solution so I built a custom image to inject .netSDK to my pod.
FROM jenkins/inbound-agent
USER root
RUN apt-get update;
RUN apt install wget
RUN wget https://packages.microsoft.com/config/debian/10/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
RUN dpkg -i packages-microsoft-prod.deb
RUN rm packages-microsoft-prod.deb
RUN apt-get install -y apt-transport-https && \
  apt-get update && \
  apt-get install -y dotnet-sdk-5.0
USER jenkins
I just followed the steps from here.
After That I made sure that Jenkins will pull this new image when claiming a pod.
However when I run this pipeline:
pipeline {
    parameters{
        string(name: 'url', description: 'repository url')
        string(name: 'branch', description: 'branch name')
        string(name: 'agent', description: 'agent name')
    }
  agent { label "${params.agent}" }
  stages {
    stage('test') {
      steps {
            sh 'dotnet --info'
        }
    }
...
    }   
  }
}
it throws an error message: dotnet: not found
/home/jenkins/agent/workspace/pipeline_DotnetBuild#tmp/durable-eb21aaa2/script.sh: 1:
/home/jenkins/agent/workspace/pipeline_DotnetBuild#tmp/durable-eb21aaa2/script.sh: dotnet: not found
So I did connect to the pod in bash mode to see what’s going on.
And I could execute:
jenkins#pod-f9xm0:~$ dotnet
Usage: dotnet [options]
Usage: dotnet [path-to-application]
…
The dotnet file is located in usr/bin/dotnet as well inside the pod.
So I am wondering what is going on here? I clearly misunderstand some concepts.
Thank you for your help and explanations!

Answer 1

After replicating your issue as closely as possible, I was getting similar results.
Starting dotnet from script with sh 'dotnet --info' is throwing an error
jenkins#157d7dfc5949:~$ cat test.sh
sh 'dotnet --info'
jenkins#157d7dfc5949:~$ ./test.sh
sh: 0: Can't open dotnet --info
Replacing sh 'dotnet --info' with /bin/bash -c dotnet --info fixed the issue.
jenkins#157d7dfc5949:~$ cat test.sh
/bin/bash -c dotnet --info
jenkins#157d7dfc5949:~$ ./test.sh
Usage: dotnet [options]
Usage: dotnet [path-to-application]
Options:
-h|--help Display help.
--info Display .NET information.
--list-sdks Display the installed SDKs.
--list-runtimes Display the installed runtimes.
path-to-application:
The path to an application .dll file to execute.