The runtime gives you a real shell. Use it well: most command failures and data-loss accidents come from sloppy quoting, ignored exit codes, or unbounded commands — not from the tool itself. This skill is the discipline, not a wrapper.

Core rules

Check the exit code. 0 means success; anything else is a failure. Never assume a command worked because it printed something. In a script, fail fast:
```
set -euo pipefail
```
-e exits on the first error, -u errors on unset variables, -o pipefail makes a pipeline fail if any stage fails (not just the last).
Quote every variable. Use "$var", not $var. Unquoted expansions split on whitespace and glob — the classic source of "it worked until a path had a space." For lists, use arrays: args=(--flag "value"); cmd "${args[@]}".
Capture output deliberately.
- out=$(cmd) captures stdout into a variable (trailing newlines stripped).
- cmd > out.txt 2> err.txt splits streams to files.
- cmd > all.txt 2>&1 merges stderr into stdout.
- cmd 2>/dev/null discards stderr only when you genuinely don't need it.
Bound long-running commands with a timeout so a hang can't stall the agent:
```
timeout 30s some-slow-command
```
timeout exits 124 when it kills the command — check for it.
Inspect before you destroy. For rm, mv, glob deletes, and anything with --force: print what will be affected first (ls, echo, --dry-run), confirm it's what you expect, then run. Never rm -rf a path built from an unvalidated variable.

Composition

Pipes a | b stream a's stdout into b's stdin. With pipefail set, the pipeline's exit code reflects any failed stage.
&& / || chain on success / failure: build && test runs test only if build succeeded.
xargs turns a list into arguments; prefer -0 with find … -print0 to be safe with odd filenames: find . -name '*.tmp' -print0 | xargs -0 rm.
Subshells ( … ) isolate cd and environment changes so they don't leak into the rest of your script.

Safety checklist before running a command

Is every variable quoted?
Will a non-zero exit be noticed (or is this in a set -e script)?
Could this delete or overwrite something? Did I preview it?
Could it hang? Does it need a timeout?
Am I about to leak a secret into the process list or logs? (Pass secrets via environment variables or files, not as command-line arguments — argv is visible to other processes.)

Más de este repositorio

mismo repositorio

csv-process

calliopeai/astrolift-skills

Read, filter, select, aggregate, and join CSV / tabular data without spinning up a full data stack.

2026-06-190

data-transform

calliopeai/astrolift-skills

jq-style select, filter, and reshape over JSON and YAML — extract paths, map arrays, and filter records without writing throwaway code.

2026-06-190

export

calliopeai/astrolift-skills

Write a dataset (array of records) to CSV, JSON, XLSX, or PDF through one interface — format chosen by the output extension.

2026-06-190

file-ops

calliopeai/astrolift-skills

Read, write, search, and edit files in the workspace safely — atomic writes, exact-match edits, and recursive content search.

2026-06-190

git

calliopeai/astrolift-skills

Everyday git — clone, branch, stage, diff, commit, and push, with a safe, predictable workflow.

2026-06-190

http-request

calliopeai/astrolift-skills

Make HTTP/REST requests with auth, custom headers, query/body, pagination, retries with backoff, and structured error handling.

2026-06-190

shell

Core rules

Check the exit code. 0 means success; anything else is a failure. Never assume a command worked because it printed something. In a script, fail fast:

set -euo pipefail

-e exits on the first error, -u errors on unset variables, -o pipefail makes a pipeline fail if any stage fails (not just the last).

Quote every variable. Use "$var", not $var. Unquoted expansions split on whitespace and glob — the classic source of "it worked until a path had a space." For lists, use arrays: args=(--flag "value"); cmd "${args[@]}".

Capture output deliberately.

out=$(cmd) captures stdout into a variable (trailing newlines stripped).
cmd > out.txt 2> err.txt splits streams to files.
cmd > all.txt 2>&1 merges stderr into stdout.
cmd 2>/dev/null discards stderr only when you genuinely don't need it.

Bound long-running commands with a timeout so a hang can't stall the agent:

timeout 30s some-slow-command

timeout exits 124 when it kills the command — check for it.

Inspect before you destroy. For rm, mv, glob deletes, and anything with --force: print what will be affected first (ls, echo, --dry-run), confirm it's what you expect, then run. Never rm -rf a path built from an unvalidated variable.

Composition

Pipes a | b stream a's stdout into b's stdin. With pipefail set, the pipeline's exit code reflects any failed stage.

&& / || chain on success / failure: build && test runs test only if build succeeded.

xargs turns a list into arguments; prefer -0 with find … -print0 to be safe with odd filenames: find . -name '*.tmp' -print0 | xargs -0 rm.

Subshells ( … ) isolate cd and environment changes so they don't leak into the rest of your script.

Safety checklist before running a command

Is every variable quoted?

Will a non-zero exit be noticed (or is this in a set -e script)?

Could this delete or overwrite something? Did I preview it?

Could it hang? Does it need a timeout?

Am I about to leak a secret into the process list or logs? (Pass secrets via environment variables or files, not as command-line arguments — argv is visible to other processes.)