just-bash by Vercel Labs
Ranked 8 of 12 shells by recommenders
A sandboxed bash-like shell in TypeScript for AI agents, fast because it starts no processes. Critics say its incompatibilities with real bash make it leaky.
A sandboxed bash-like shell in TypeScript for AI agents, fast because it starts no processes. Critics say its incompatibilities with real bash make it leaky.
20 people gave an opinion
- recommend it
- 11
- criticize it
- 9
- approval share
- 55%
Recommended in 5 of 13 months
- November 2025: not recommended
- December 2025: not recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: not recommended
- June 2026: not recommended
- July 2026: not recommended
- August 2026: not recommended
- September 2026: recommended
- October 2026: not recommended
- November 2026: not recommended (month in progress)
Why it doesn’t carry the badge
- 11 people recommend itNeeds 10 or more, met.
- 1.2 recommenders for every criticNeeds 2 to 1 or better, not met.
- Recommended in 5 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Lightweight, fast sandbox for agents
“In practice it is actually extremely fast because there is no process fork.”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” “you can give it an lightweight secure execution environment like just-bash”
Comment from 30 Sep 2026 in “You said no MCP” “Clever use of just-bash to avoid the sandbox cold-start problem”
Comment from 4 Apr 2026 in “We replaced RAG with a virtual filesystem for our AI documentation assistant” Clever, cool approach overall
“Clever use of just-bash to avoid the sandbox cold-start problem”
Comment from 4 Apr 2026 in “We replaced RAG with a virtual filesystem for our AI documentation assistant” “I love the approach of just bash as well. Super cool!”
Comment from 27 Feb 2026 in “just-bash: Bash for Agents” “it worked very well and was undeniably pretty cool”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” - Comment from 26 Feb 2026 in “just-bash: Bash for Agents”
Works reliably in practice
“In practice it works great. I haven't seen a failed command in a while”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” “it worked very well and was undeniably pretty cool”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents”
What people warn about
Each mark is one comment
Incompatible with real bash behavior
“the issue is to make the tools compatible with the official tools otherwise you will get odd behaviour”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” “I don't think the current incompatibilities can be worked around.”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” “It was never trained on an incompatible, partial implementation.”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” - Comment from 26 Feb 2026 in “just-bash: Bash for Agents”
Forked and rebranded; controversial
“Is this tactic of forking and rebranding some sort of open source embrace, extend, extinguish thing?”
Comment from 15 Mar 2026 in “Cloudflare forked just-bash and they really, really should not have” “the reasons for the fork seem to be largely LLM hallucinated, I think it counts as a slop-fork”
Comment from 15 Mar 2026 in “Cloudflare forked just-bash and they really, really should not have” “Vercel have been reimplementing Bash and dozens of other common Unix tools in TypeScript”
Comment from 10 Mar 2026 in “JSLinux Now Supports x86_64” Unclear benefit over sandboxed bash
“I suspect that something like this will be a far too leaky abstraction.”
Comment from 26 Feb 2026 in “just-bash: Bash for Agents” “Not sure why I would ever want to use this over bash in a sandboxed VM.”
Comment from 27 Feb 2026 in “just-bash: Bash for Agents”
Other shells people recommend
The four most recommended other shells, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| Bash | 171 | 127 | 57% | 12 | 20 yrs7 owners | — |
| PowerShell | 156 | 92 | 63% | 12 | — | — |
| fish shell | 97 | 20 | 83% | 12 | 5 yrs11 owners | Approved |
| Nushell | 92 | 15 | 86% | 11 | 1.7 yrs5 owners | Approved |
| just-bash by Vercel LabsThis page | 11 | 9 | 55% | 5 | — | — |
What people said
23 of the 26 comments that mention it, newest first. Each links to the original comment.
“you can give it an lightweight secure execution environment like just-bash”
“Clever use of just-bash to avoid the sandbox cold-start problem”
“the reasons for the fork seem to be largely LLM hallucinated, I think it counts as a slop-fork”
“Is this tactic of forking and rebranding some sort of open source embrace, extend, extinguish thing?”
“Vercel have been reimplementing Bash and dozens of other common Unix tools in TypeScript”
“For CLI and file operations we have Vercel's just-bash”
“I love the approach of just bash as well. Super cool!”
“Failed with a simple `> /dev/null` redirection.”
“Not sure why I would ever want to use this over bash in a sandboxed VM.”
“i think its still useful if we are bound to js/ts ecosystem”
“It’s cool to see this project and others pop up.”
“In practice it works great. I haven't seen a failed command in a while”
“In practice it is actually extremely fast because there is no process fork.”
“I suspect that something like this will be a far too leaky abstraction.”
“I don't think the current incompatibilities can be worked around.”
“it worked very well and was undeniably pretty cool”
“After all you're limiting discovery with name like that.”
“Incompatibilities don't matter much provided your error messages are actionable”
“the issue is to make the tools compatible with the official tools otherwise you will get odd behaviour”
“isn't this incredibly slow compared to native cli tools?”
“Let me know when just-bash is able to run it.”
“It was never trained on an incompatible, partial implementation.”
“That's a lot of incompatibilities.”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.