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馃悰 fix(activation): escape the bash prompt for both PS1 passes - #3390
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bash decodes its backslash prompt escapes in PS1 before it expands the result, turning \\ into \ and \$ into $ (or # for root). The activate script escaped the environment name for the expansion pass only, so a backslash in the name undid the escaping, and a name such as a\$(touch PWNED) ran the command each time the prompt was drawn. Escape the name a second time under bash so both passes leave it literal. zsh does no decode pass, so it keeps the single escaping.
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Oct 12, 2026
#3390 escapes the bash prompt twice, once for bash's prompt-escape decode and once for its expansion. `test_bash` renders the prompt with `${PS1@P}` on bash 4.4+, but macOS ships bash 3.2, where it falls back to a `sed` that strips one layer of escapes. 馃И The rendered prompt then kept `\$` and `` \` `` and `test_bash` failed on every macOS job, as on [#3391](https://github.com/pypa/virtualenv/actions/runs/38189937681/job/114620308443). The fallback now runs the same `sed` expression twice. On bash 5.3 its output matches `${PS1@P}` for the tester's environment name and the names from the #3390 regression cases.
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bash handles
PS1in two passes each time it draws the prompt: it first decodes backslash prompt escapes, turning\\into\and\$into$(or#for root), and then expands the result. The bashactivatescript escaped the environment name for the expansion pass only (#3326), so a backslash in the name undoes that escaping. 馃攼 A name such asa\$(touch PWNED), from the directory,--promptorVIRTUALENV_PROMPT, runs the command each time bash draws the prompt. For root,\$decodes to#, so the same name renders wrong but runs nothing.Under bash,
activatenow escapes backslashes, dollar signs and backticks a second time, so both passes leave the name literal. zsh does no decode pass, so it keeps the single escaping added in 5b91536. The prompt tests gain cases for a backslash before$(...)and before backticks, and for names with a backslash before$, before a backtick, doubled, and trailing; they render through bash 5.2 and zsh 5.9 and pass as root and as an unprivileged user.Every release up to 21.14.6 is affected, and earlier releases before 21.13.0 do not escape the name at all.