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od: `-S` with `-Ax` prints 7-digit hex offsets instead of 6

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  • #15625 by @ozenyunus35 — merged

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
86/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
rust
Domain
cli

Research direction

Start in src/uu/od/src/od.rs at extract_strings_from_input, where the issue identifies the string offset format, then compare it with InputOffset::format_byte_offset in input_offset.rs. Reproduce with printf 'a\0' | od -Ax -S1; done when the strings output uses six hex digits and matches the normal dump and GNU od behavior.

Written by the indexing model from the issue text.

Description

U - od

With -S/--strings and -Ax, uutils od zero-pads string offsets to 7 hex digits. GNU od pads them to 6, and so does uutils od's own normal dump with -Ax. Decimal (-Ad) and octal (-Ao) offsets already use 7 digits in both.

The GNU manual does not spell out the width; it describes -A RADIX as selecting "the base in which file offsets are printed". GNU 9.12 uses 6 hex digits for every output mode, -S included.

printf 'a\0' | od -Ax -S1
# GNU 9.12: 000000 a
# uutils:   0000000 a

printf 'a\0' | od -Ax -c | head -1
# GNU 9.12: 000000   a  \0
# uutils:   000000   a  \0       (same uutils build, normal dump: 6 digits)

Versions. uutils main eee56033d28bf7ef5cc816286b048779d57fb803 (2026-10-21) and the 0.12.0 release binary, macOS 26 aarch64 (the loop found it on Linux x86_64), LC_ALL=C, compared with GNU coreutils 9.12.

Where. extract_strings_from_input in src/uu/od/src/od.rs formats the offset itself with {offset:07x}, while InputOffset::format_byte_offset (input_offset.rs) uses {:06x} for hex.

Related: #11613, #11744, #13396 (offset values with -S -N), not the width.

Found with an automated differential tester that compares uutils with GNU 9.12.

Reproduction steps
export LC_ALL=C
printf 'a\0' | od -Ax -S1
# GNU 9.12: 000000 a
# uutils:   0000000 a
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