pdp11-strip — user guide

pdp11-strip removes the symbol table and relocation from a PDP-11 a.out, in place — the 2.9BSD strip. It reads the header, detects which a.out form it is looking at, drops the symbol table and relocation, and sets the no-relocation flag. It runs on your host.

For how it works inside — the header poke, the overlay-aware copy, the First Edition special case, and the hardening — see the design document.

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1. Synopsis

pdp11-strip [-n] file ...

Each file is edited in place; several may be given. -n, when present, must be the first argument.

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2. What it removes

The default removes everything a linker or debugger added and a finished program does not need to run — the symbol table and the relocation — and sets the header's no-relocation flag. What is left is the header (with a_syms zeroed), the text, and the initialized data: smaller, no longer relinkable, but still runnable.

An object that is already stripped — its symbol table gone and its no-relocation flag already set — is left alone and reported (and counts toward the exit status; see §5).

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3. Options

option	meaning
(none)	full strip — drop the symbol table and relocation, set the no-relocation flag
-n	keep only the name list (the symbol table); discard text and data

-n is the complement of a plain strip: it writes a header with the text, data, and bss sizes zeroed and copies out just the symbol table, so you are left with the name list on its own.

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4. What it reads

The a.out form is detected, never declared:

• the ordinary magics 0407 (normal), 0410 (read-only text), and 0411 (separated I&D) — the common case, stripped by one format-agnostic code path that never reads a symbol (see design §1);
• the auto-overlay magics 0430/0431 — the overlay text segments named by the overlay header are preserved; only the trailing symbols and relocation are dropped (design §2);
• First Edition 0405, whose text size includes its 12-byte header (design §3).

A file that is not a PDP-11 a.out is reported and skipped.

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5. Exit status

• 0 — every file was stripped successfully.
• nonzero — the number of files that failed. strip returns the count, and a file counts as failed if it is not a PDP-11 a.out, is already stripped, or hits an I/O error. (Note that already-stripped is a failure here, not a silent success.)
• 75 (EX_TEMPFAIL) — a temporary file could not be created.

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6. Examples

pdp11-strip prog                  # drop symbols + relocation, in place
pdp11-strip *.o                   # strip many files in place
pdp11-strip -n prog               # keep only the symbol table (the name list)

The companion pdp11-objcopy does the raw-image and single-segment extraction that is the other half of an a.out toolkit; stripping symbols is this tool's job, not its.

Continue to the design document for the header rewrite, the overlay-aware copy, and the hostile-header guards.