Learn-skills.dev asciinema-record

Record a terminal session to a named .cast file using asciinema, trim the recording to marked content, and optionally convert it to a GIF using agg.

install

source · Clone the upstream repo

git clone https://github.com/NeverSight/learn-skills.dev

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/NeverSight/learn-skills.dev "$T" && mkdir -p ~/.claude/skills && cp -r "$T/data/skills-md/abuxton/skills/asciinema-record" ~/.claude/skills/neversight-learn-skills-dev-asciinema-record && rm -rf "$T"

manifest: data/skills-md/abuxton/skills/asciinema-record/SKILL.md

source content

Asciinema Record

Record a focused terminal session using asciinema, trim the raw

.cast

file to the content between

start here

end here

markers, and optionally render an animated GIF with agg.

Role

You are an expert in terminal recording, asciinema workflows, and developer experience tooling.

Derive a short, descriptive filename from the task being demonstrated (e.g. a file-listing demo →
```
ls.cast
```
)
Produce clean recordings by stripping shell preamble and teardown, keeping only the content the viewer needs to see
Handle the full pipeline: record → trim → (optionally) render GIF
Never overwrite an existing
```
.cast
```
file without confirmation

Workflow

Derive the cast filename — From the task description, choose a concise snake_case name that identifies what is being demonstrated (e.g. "show directory listing" →
```
ls
```
, "install dependencies" →
```
npm_install
```
, "run tests" →
```
test_run
```
). The output file will be
```
./tmp/<name>.cast
```
.
Ensure the output directory exists — Run:
```
mkdir -p ./tmp
```
Start the recording — Launch an asciinema session targeting the output file:
```
asciinema rec ./tmp/<name>.cast
```
This opens an interactive shell inside the recording session.
Emit the start marker — As the very first command inside the recorded session, run:
```
echo "start here"
```
Perform the demonstration — Run the commands that illustrate the task. Keep the session focused; avoid long pauses or unrelated commands.
Emit the end marker — When the demonstration is complete, run:
```
echo "end here"
```
End the recording session — Exit the recorded shell:
```
exit
```
asciinema writes and closes
```
./tmp/<name>.cast
```
.

Trim the cast file — Use the Python script in

references/trim_cast.py

to strip everything outside the markers, always preserving the header (line 1):

python3 skills/asciinema-record/references/trim_cast.py ./tmp/<name>.cast

The script rewrites the file in-place: header line + only the events between (exclusive of) the

start here

and

end here

marker lines.

Render a GIF (optional) — If the task calls for a GIF or the
```
agg
```
utility is available, convert the cast:
```
agg ./tmp/<name>.cast ./tmp/<name>.gif
```
The GIF shares the same base name as the cast file.

Notes

The
```
start here
```
and
```
end here
```
strings must appear as plain
```
echo
```
output in the cast; the trim script searches for them as substrings in the event data.
If
```
agg
```
is not installed, skip step 9 and note the cast file location for the user to convert manually.
The
```
./tmp/
```
directory should be added to
```
.gitignore
```
if recordings are not meant to be committed; add the specific files explicitly if they should be.
See
```
_assets/asciinema/
```
for example
```
.cast
```
and
```
.gif
```
reference files.