Provide posix-compatible shell scripts for JS7 components

Current Situation

• The JS7 provides
  • a start script for Controller and Agent: controller.sh, agent.sh
  • an instance start script for Controller and Agents: controller_instance.sh, agent_<port>.sh
  • a kill script for running tasks with Agents: kill_task.sh
• The above scripts are roughly compatible for a number of Unix environments, however, support for specific operating systems and shell versions is not clearly defined.

Desired Behavior

• All shell scripts are re-written for full posix-compatibility
• Supported OS shells include: current versions of ksh, bash, zsh, dash
• Supported OS products include
  • OS in scope of testing by SOS: CentOS/RedHat, Ubuntu, Oracle Linux, Amazon Linux, AIX, MacOS
  • OS out of scope of testing by SOS: Alma Linux, Rocky Linux
    • "out of scope" means that SOS will not actively test such platforms but will apply required changes if indicated by the JS7 community.
• Shell scripts make use of traps for cleanup of temporary files and environment variables.
• Quoting: extensive quoting of variables
• Specific commands are used in a compatible way:
  • Compatible use of grep: instead of egrep use grep -E
  • Compatible use of tar: instead of tar -xvzf use gzip -c -d < ... | tar -xf - -C ...
• Generally stick to recommendations from
  • Portable Shell Programming: https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.71/html_node/Portable-Shell.html
  • Shell Check: https://www.shellcheck.net/