Run bash scripts (#!/bin/bash)

[noahtalerman]

Goal

User story
As an IT admin,
I want to run scripts with #!/bin/bash on macOS/Linux
so that I don't have to rewrite my existing bash scripts to prevent them from failing.

Key result

Deliver prioritized customer request

Original requests

• Ability to run bash scripts #22627

Context

• Product designer: @rachaelshaw

Changes

Product

• UI changes: Figma
• CLI (fleetctl) usage changes: No changes
• YAML changes: No changes
• REST API changes: No changes
• Fleet's agent (fleetd) changes: No changes
• Activity changes: No changes
• Permissions changes: No changes
• Changes to paid features or tiers: No changes
• Transparency changes: No changes
• First draft of test plan added
• Other reference documentation changes: Update scripts guide
• Once shipped, requester has been notified
• Once shipped, dogfooding issue has been filed

Engineering

• Test plan is finalized
• Feature guide changes: Update UI texts as part of this task.
• Database schema migrations: no need.
• Load testing: No need.
• PoC PR Allow use of bash as a script interpreter #25449 is attached.

ℹ️  Please read this issue carefully and understand it. Pay special attention to UI wireframes, especially "dev notes".

QA

Risk assessment

• Requires load testing: No need.
• Risk level: Low
• Risk description: A potential bug in running the bash scripts or affecting other scripts. Low risk cause this can easily be caught by QA.

Test plan

1. Upload a script that begins with #!/bin/bash and contains bash-specific features (e.g. uses arrays)
   • Run the script on a macOS host
   • Run the script on a Linux host
2. Upload the same script, but without #!/bin/bash on the first line.
   • Try running again; should fail because it runs using #!/bin/sh

Testing notes

Confirmation

1. Engineer (@____): Added comment to user story confirming successful completion of test plan.
2. QA (@____): Added comment to user story confirming successful completion of test plan.

[allenhouchins]

Today I learned that even though you can't upload bash scripts today, you can spawn bash commands from sh scripts. Example:

#!/bin/sh
#
# A script to find the line "#WaylandEnable=False" in /etc/gdm3/custom.conf,
# uncomment it if present, and then restart the GDM service.

FILE="/etc/gdm3/custom.conf"
SEARCH_LINE="#WaylandEnable=false"
UNCOMMENTED_LINE="WaylandEnable=false"

# Check if the file contains a line starting with "#WaylandEnable=False"
if grep -xq '^#WaylandEnable=false$' /etc/gdm3/custom.conf; then
  echo "Found '$SEARCH_LINE'. Uncommenting it..."
  # Use sed to remove the leading '#' on that specific line
  sed -i 's/^#WaylandEnable=false$/WaylandEnable=false/' $FILE
  
  echo "Restarting the GDM service to apply changes..."
  systemctl daemon-reload # Make sure systemctl is aware of changes
  systemctl restart gdm3

  # Restart Fleet Desktop
  nohup bash -c "sleep 10 && systemctl restart orbit" >/dev/null 2>&1 & # <-----------

else
  echo "Either '$SEARCH_LINE' is already uncommented or the line is missing."
fi

I had to do this because sh doesn't support commands like disown and other background process capabilities.