docs: improved documentation on interactive runs

[cmeesters]

Added a note on (hopefully more stable) interactive runs

Summary by CodeRabbit

• Documentation
  • Updated interactive SLURM usage guidance with a new recommended workflow for managing SLURM environment variables when running Snakemake jobs. Enhanced documentation includes improved examples and explanatory notes for clarity.

[coderabbitai]

Walkthrough

Updated SLURM interactive usage guidance in docs/further.md by replacing an admonition about extra wait times with a new workflow that unsets SLURM-related environment variables and executes Snakemake via srun. Preserves information about salloc subshell behavior with accompanying examples and rationale.

Changes

Cohort / File(s)	Summary
SLURM Usage Documentation docs/further.md	Replaced outdated guidance on interactive SLURM jobs with updated workflow: unsetting SLURM environment variables, executing via srun, and added explanatory notes with examples clarifying the rationale and salloc subshell behavior.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Poem

🐰 A tale of SLURM so fine and bright,
Variables unset, workflows take flight!
No more waits that linger long,
With srun's power, we hop along! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'docs: improved documentation on interactive runs' directly aligns with the changeset, which updates guidance on interactive SLURM usage in docs/further.md with a new workflow for executing Snakemake runs.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch docs/update_on_interactive_jobs

📝 Coding Plan

• Generate coding plan for human review comments

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@docs/further.md`:
- Line 839: The line using Bash-specific expansion "unset ${!SLURM*}" is not
portable; replace it with a POSIX-safe approach: iterate over environment names
matching the SLURM_ prefix (e.g. parse `env` output and extract names starting
with "SLURM_") and call unset on each name, or alternatively make the snippet
explicitly require Bash (add a shebang or note) and keep the current expansion;
update the occurrence of "unset ${!SLURM*}" accordingly.
- Around line 839-840: The example currently unsets SLURM_* then runs srun which
breaks allocation binding because srun needs SLURM_JOB_ID (or --jobid); either
preserve required variables (keep SLURM_JOB_ID and any other needed SLURM_* env
vars) when running srun, or capture the job id before unsetting and pass it
explicitly to srun (use the captured value with --jobid="$SLURM_JOB_ID") so that
the srun snakemake invocation can attach to the salloc allocation; update the
snippet around the unset ${!SLURM*} and the srun snakemake call accordingly.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: d8de6c4a-16f3-4ecd-be75-fd8a4b6357cc

📥 Commits

Reviewing files that changed from the base of the PR and between c6e8893 and e56bb06.

📒 Files selected for processing (1)

• docs/further.md

[coderabbitai]

⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🌐 Web query:

Is unset ${!SLURM*}POSIX-compliant, or Bash-specific? What is a shell-portable way to unset all environment variables prefixed withSLURM_?

💡 Result:

unset ${!SLURM*} is Bash-specific, not POSIX: ${!prefix*} is a Bash parameter-expansion form that expands to the names of variables whose names begin with prefix (i.e., “names matching prefix”).[1][2]

A POSIX /bin/sh–portable way to unset all environment variables whose names start with SLURM_ is to generate the variable names from env and pass them to unset:

# POSIX sh
for name in $(env | sed -n 's/^\(SLURM_[A-Za-z_][A-Za-z0-9_]*\)=.*/\1/p'); do
  unset "$name"
done

unset itself (for unsetting variables by name) is specified by POSIX.[3]

Sources: Bash manual on indirect/prefix name expansions[1], BashFAQ noting ${!...} is not POSIX[2], POSIX unset spec[3].

[1] (gnu.org)
[2] (mywiki.wooledge.org)
[3] (mirror.math.princeton.edu)

Citations:

• 1: https://www.gnu.org/s/bash/manual/html_node/Shell-Parameter-Expansion.html
• 2: https://mywiki.wooledge.org/BashFAQ/006?utm_source=openai
• 3: https://mirror.math.princeton.edu/pub/oldlinux/Linux.old/Ref-docs/POSIX/C952.pdf

---

Use a shell-portable way to unset SLURM_* variables.

unset ${!SLURM*} uses Bash-specific parameter expansion and will fail in other shells (sh, dash, ksh, zsh, etc.). Replace with a POSIX-portable approach:

for var in $(env | sed -n 's/^\(SLURM_[A-Za-z_][A-Za-z0-9_]*\)=.*/\1/p'); do
  unset "$var"
done

Alternatively, explicitly require Bash in the snippet if preferred.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@docs/further.md` at line 839, The line using Bash-specific expansion "unset
${!SLURM*}" is not portable; replace it with a POSIX-safe approach: iterate over
environment names matching the SLURM_ prefix (e.g. parse `env` output and
extract names starting with "SLURM_") and call unset on each name, or
alternatively make the snippet explicitly require Bash (add a shebang or note)
and keep the current expansion; update the occurrence of "unset ${!SLURM*}"
accordingly.

[coderabbitai]

⚠️ Potential issue | 🔴 Critical

🧩 Analysis chain

🌐 Web query:

When launched inside an existing sallocsession, doessrunrequireSLURM_JOB_ID(or otherSLURM_* env vars) to bind to that allocation? If yes, what is the recommended command order when needing a clean environment for child processes?

💡 Result:

Yes. To have srun create a job step inside an existing allocation, it must be able to identify the parent allocation via either SLURM_JOB_ID or srun --jobid=<jobid>; --jobid “behave[s] exactly as if the SLURM_JOB_ID environment variable was set.” [1][2]

Recommended order when you need a clean environment:

1. Start/enter the allocation normally (so you can capture the job id), e.g. salloc ...
2. Save the job id, then scrub the environment, and call srun using --jobid:

# inside the salloc shell
JOBID="$SLURM_JOB_ID"

env -i HOME="$HOME" PATH="/usr/bin:/bin" TERM="$TERM" \
  srun --jobid="$JOBID" --export=NONE <your_command>

Notes:

• env -i cleans the environment for the srun client process, so you must pass the allocation identity via --jobid (since you removed SLURM_JOB_ID). [1][2]
• --export=NONE prevents your (now-minimal) submission environment from being propagated to the launched tasks/step (Slurm will still set its own SLURM_* variables for the step). [2]

Sources:
[1] Cornell CVW “Execution: srun” (existing allocation requires --jobid or SLURM_JOB_ID)
[2] Slurm srun man page (--jobid, --export)

---

The code as shown will break allocation binding—srun requires SLURM_JOB_ID (or --jobid parameter) to attach to the salloc allocation.

Update the example to either:

1. Preserve SLURM_JOB_ID (and other required SLURM_* vars), or
2. Capture the job ID before unsetting and pass it explicitly: srun --jobid="$SLURM_JOB_ID" snakemake ...

Unsetting SLURM_* without providing the --jobid parameter will cause srun to fail to bind to the existing allocation.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@docs/further.md` around lines 839 - 840, The example currently unsets SLURM_*
then runs srun which breaks allocation binding because srun needs SLURM_JOB_ID
(or --jobid); either preserve required variables (keep SLURM_JOB_ID and any
other needed SLURM_* env vars) when running srun, or capture the job id before
unsetting and pass it explicitly to srun (use the captured value with
--jobid="$SLURM_JOB_ID") so that the srun snakemake invocation can attach to the
salloc allocation; update the snippet around the unset ${!SLURM*} and the srun
snakemake call accordingly.