Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.277 ·

Env-var-prefix stripping in shell-command normalization now conditional

Shell-command normalization can now skip stripping VAR=value prefixes when matching permission rules

TierUnder the hoodhow much it should matter to you
Useful2my rating, 1 to 5
Signal2worth watching, 1 to 5
AreaBash Safetywhat it touches
KindInternal Changesin v2.1.277,
Under the hood

Shell-command normalization can now skip stripping VAR=value prefixes when matching permission rules

What

When Claude Code checks a shell command against permission rules, it first normalizes the command text by stripping leading VAR=value environment-variable assignments and shell wrapper keywords like builtin or noglob. That stripping step is now controlled by a new boolean parameter, n, which defaults to true. Several existing call sites already pass false, meaning they skip the VAR=value stripping and match against the command text as written.

Why

This lets some permission checks see the full original command, including any environment-variable prefix, instead of always having that prefix stripped away first. That can affect whether a permission rule matches a command that starts with a variable assignment.

What the documentation says
VAR Configuration reference modified, high confidence Each folder is interpreted on the machine the session runs on. For a Code session on an SSH host, `~` means the remote user's home, an entry that references a `%VAR%` is ignored there (environment variables belong to the machine that defin… see the edit
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtThe finding does not say which call sites pass false or what practical difference this makes for a user writing permission rules.
Anthropic's documentation agreesVAR on Configuration reference

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